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Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2020	Jul. 27, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Trading Symbol	MNOV
Entity Registrant Name	MEDICINOVA, INC.
Entity Central Index Key	0001226616
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		44,372,943
Entity Shell Company	false
Entity File Number	001-33185
Entity Tax Identification Number	33-0927979
Entity Address, Address Line One	4275 Executive Square
Entity Address, Address Line Two	Suite 300
Entity Address, City or Town	La Jolla
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92037
City Area Code	858
Local Phone Number	373-1500
Entity Current Reporting Status	Yes
Document Quarterly Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	DE
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, $0.001 par value
Security Exchange Name	NASDAQ

Consolidated Balance Sheets - USD ($)	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 60,440,450	$ 63,792,657
Prepaid expenses and other current assets	605,677	511,916
Total current assets	61,046,127	64,304,573
Goodwill	9,600,240	9,600,240
In-process research and development	4,800,000	4,800,000
Property and equipment, net	32,927	40,550
Other non-current assets	359,147	459,811
Total assets	75,838,441	79,205,174
Current liabilities:
Accounts payable	576,506	451,326
Accrued expenses and other liabilities	2,197,254	1,776,912
Total current liabilities	2,773,760	2,228,238
Long-term deferred revenue	1,694,163	1,694,163
Deferred tax liability	201,792	201,792
Other non-current liabilities	75,783	186,358
Total liabilities	4,745,498	4,310,551
Commitments and contingencies
Stockholders’ equity:
Common stock, $0.001 par value; 100,000,000 shares authorized at June 30, 2020 and December 31, 2019; 44,263,578 and 43,908,065 shares issued and outstanding at June 30, 2020 and December 31, 2019, respectively	44,264	43,908
Additional paid-in capital	447,379,208	444,016,341
Accumulated other comprehensive loss	(92,796)	(92,681)
Accumulated deficit	(376,237,733)	(369,072,945)
Total stockholders’ equity	71,092,943	74,894,623
Total liabilities and stockholders' equity	$ 75,838,441	$ 79,205,174

Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	44,263,578	43,908,065
Common stock, shares outstanding	44,263,578	43,908,065

Consolidated Statements of Operations and Comprehensive Loss - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating expenses:
Research, development and patents	$ 2,199,036	$ 1,465,512	$ 3,449,781	$ 3,099,390
General and administrative	2,311,330	2,716,509	3,985,084	6,061,990
Total operating expenses	4,510,366	4,182,021	7,434,865	9,161,380
Operating loss	(4,510,366)	(4,182,021)	(7,434,865)	(9,161,380)
Interest income	63,691	307,574	286,971	611,819
Other expense	(4,554)	(7,429)	(16,894)	(29,505)
Net loss applicable to common stockholders	$ (4,451,229)	$ (3,881,876)	$ (7,164,788)	$ (8,579,066)
Basic and diluted net loss per common share	$ (0.10)	$ (0.09)	$ (0.16)	$ (0.20)
Shares used to compute basic and diluted net loss per common share	44,091,568	43,069,007	44,020,429	42,770,117
Net loss applicable to common stockholders	$ (4,451,229)	$ (3,881,876)	$ (7,164,788)	$ (8,579,066)
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	5	3,355	(115)	1,574
Comprehensive loss	$ (4,451,224)	$ (3,878,521)	$ (7,164,903)	$ (8,577,492)

Consolidated Statements of Stockholders' Equity - USD ($)	Total	Common stock	Additional paid-in capital	Accumulated other comprehensive income (loss)	Accumulated deficit
Balance at Dec. 31, 2018	$ 73,107,612	$ 42,081	$ 429,289,968	$ (93,150)	$ (356,131,287)
Balance, shares at Dec. 31, 2018		42,081,306
Share-based compensation	2,699,500		2,699,500
Issuance of shares under an employee stock purchase plan (ESPP)	16,903	$ 2	16,901
Issuance of shares under an employee stock purchase plan (ESPP), shares		2,401
Issuance of common stock under at-the-market equity distribution and sales agreements, net of offering costs	(8,532)		(8,532)
Issuance of common stock for option exercises	3,920,735	$ 978	3,919,757
Issuance of common stock for option exercises, shares		977,454
Net loss	(4,697,190)				(4,697,190)
Foreign currency translation adjustments	(1,781)			(1,781)
Balance at Mar. 31, 2019	75,037,247	$ 43,061	435,917,594	(94,931)	(360,828,477)
Balance, shares at Mar. 31, 2019		43,061,161
Balance at Dec. 31, 2018	73,107,612	$ 42,081	429,289,968	(93,150)	(356,131,287)
Balance, shares at Dec. 31, 2018		42,081,306
Net loss	(8,579,066)
Foreign currency translation adjustments	1,574
Balance at Jun. 30, 2019	73,181,610	$ 43,099	437,940,440	(91,576)	(364,710,353)
Balance, shares at Jun. 30, 2019		43,099,161
Balance at Mar. 31, 2019	75,037,247	$ 43,061	435,917,594	(94,931)	(360,828,477)
Balance, shares at Mar. 31, 2019		43,061,161
Share-based compensation	1,842,514		1,842,514
Issuance of common stock for option exercises	180,370	$ 38	180,332
Issuance of common stock for option exercises, shares		38,000
Net loss	(3,881,876)				(3,881,876)
Foreign currency translation adjustments	3,355			3,355
Balance at Jun. 30, 2019	73,181,610	$ 43,099	437,940,440	(91,576)	(364,710,353)
Balance, shares at Jun. 30, 2019		43,099,161
Balance at Dec. 31, 2019	74,894,623	$ 43,908	444,016,341	(92,681)	(369,072,945)
Balance, shares at Dec. 31, 2019		43,908,065
Share-based compensation	596,378		596,378
Issuance of shares under an employee stock purchase plan (ESPP)	6,254	$ 2	6,252
Issuance of shares under an employee stock purchase plan (ESPP), shares		1,979
Issuance of common stock under at-the-market equity distribution and sales agreements, net of offering costs	412,692	$ 69	412,623
Issuance of common stock under at-the-market equity distribution and sales agreements, net of offering costs, shares		68,952
Net loss	(2,713,559)				(2,713,559)
Foreign currency translation adjustments	(120)			(120)
Balance at Mar. 31, 2020	73,196,268	$ 43,979	445,031,594	(92,801)	(371,786,504)
Balance, shares at Mar. 31, 2020		43,978,996
Balance at Dec. 31, 2019	$ 74,894,623	$ 43,908	444,016,341	(92,681)	(369,072,945)
Balance, shares at Dec. 31, 2019		43,908,065
Issuance of shares under an employee stock purchase plan (ESPP), shares	1,979
Issuance of common stock for option exercises, shares	143,863
Net loss	$ (7,164,788)
Foreign currency translation adjustments	(115)
Balance at Jun. 30, 2020	71,092,943	$ 44,264	447,379,208	(92,796)	(376,237,733)
Balance, shares at Jun. 30, 2020		44,263,578
Balance at Mar. 31, 2020	73,196,268	$ 43,979	445,031,594	(92,801)	(371,786,504)
Balance, shares at Mar. 31, 2020		43,978,996
Share-based compensation	1,147,154		1,147,154
Issuance of common stock under at-the-market equity distribution and sales agreements, net of offering costs	762,483	$ 141	762,342
Issuance of common stock under at-the-market equity distribution and sales agreements, net of offering costs, shares		140,719
Issuance of common stock for option exercises	438,262	$ 144	438,118
Issuance of common stock for option exercises, shares		143,863
Net loss	(4,451,229)				(4,451,229)
Foreign currency translation adjustments	5			5
Balance at Jun. 30, 2020	$ 71,092,943	$ 44,264	$ 447,379,208	$ (92,796)	$ (376,237,733)
Balance, shares at Jun. 30, 2020		44,263,578

Consolidated Statements of Cash Flows - USD ($)	6 Months Ended
Consolidated Statements of Cash Flows - USD ($)	Jun. 30, 2020	Jun. 30, 2019
Operating activities:
Net loss	$ (7,164,788)	$ (8,579,066)
Adjustments to reconcile net loss to net cash used in operating activities:
Non-cash stock-based compensation	1,743,532	4,542,014
Depreciation and amortization	10,270	12,337
Changes in assets and liabilities:
Prepaid expenses and other assets	8,583	(508,053)
Accounts payable, accrued liabilities and other liabilities	433,224	(148,832)
Net cash used in operating activities	(4,969,179)	(4,681,600)
Investing activities:
Acquisition of property and equipment	(2,604)	(4,013)
Net cash used in investing activities	(2,604)	(4,013)
Financing activities:
Proceeds from issuance of common stock, exercise of common stock options and warrants, net of issuance costs	1,613,437	4,092,573
Proceeds from issuance of equity awards under ESPP	6,254	16,903
Net cash provided by financing activities	1,619,691	4,109,476
Effect of exchange rate changes on cash and cash equivalents	(115)	561
Net change in cash and cash equivalents	(3,352,207)	(575,576)
Cash and cash equivalents, beginning of period	63,792,657	62,313,418
Cash and cash equivalents, end of period	$ 60,440,450	$ 61,737,842

Interim Financial Information

6 Months Ended

Jun. 30, 2020

Quarterly Financial Information Disclosure [Abstract]

Interim Financial Information

1. Interim Financial Information

Organization and Business

MediciNova, Inc. (the “Company” or “MediciNova”) was incorporated in the state of Delaware in September 2000 and is a public company. The Company’s common stock is listed in both the United States and Japan and trades on the NASDAQ Global Market and the JASDAQ Market of the Tokyo Stock Exchange. MediciNova is a biopharmaceutical company focused on developing novel, small molecule therapeutics for the treatment of serious diseases with unmet medical needs with a commercial focus on the United States market. The Company’s current strategy is to focus its development activities on MN-166 (ibudilast) for neurological disorders such as progressive multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), chemotherapy-induced peripheral neuropathy, degenerative cervical myelopathy, glioblastoma, and substance dependence and addiction (e.g., methamphetamine dependence, opioid dependence and alcohol dependence), as well as for acute respiratory distress syndrome (ARDS), and MN-001 (tipelukast) for fibrotic diseases such as nonalcoholic steatohepatitis (NASH) and idiopathic pulmonary fibrosis (IPF). The Company’s pipeline also includes MN-221 (bedoradrine) for the treatment of acute exacerbation of asthma and MN-029 (denibulin) for solid tumor cancers.

Basis of Presentation

The accompanying unaudited consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (GAAP) for interim financial information and with the instructions of the Securities and Exchange Commission (SEC) on Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all the information and disclosures required by GAAP for complete financial statements. In the opinion of management, the consolidated financial statements include all adjustments necessary, which are of a normal and recurring nature, for the fair presentation of the Company’s financial position and of the results of operations and cash flows for the periods presented. The accompanying unaudited consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries.

These financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto for the year ended December 31, 2019 included in the Company’s Annual Report on Form 10-K filed with the SEC. The results of operations for the interim period shown in this report are not necessarily indicative of the results that may be expected for any other interim period or for the full year. The balance sheet at December 31, 2019 has been derived from the audited financial statements at that date but does not include all the information and footnotes required by GAAP for complete financial statements.

Principles of Consolidation

The consolidated financial statements include the accounts of MediciNova, Inc. and its wholly owned subsidiaries. All intercompany transactions and balances are eliminated in consolidation.

Segment Reporting

The Company operates in a single operating segment – the acquisition and development of small molecule therapeutics for the treatment of serious diseases with unmet medical needs.

Cash and Cash Equivalents

Cash and cash equivalents consist of cash and other highly liquid investments including money market accounts.

Research, Development and Patents

Research and development costs are expensed in the period incurred. Research and development costs primarily consist of salaries and related expenses for personnel, facilities and depreciation, research and development supplies, licenses and outside services. Such research and development costs totaled $2.1 million and $1.4 million for the three months ended June 30, 2020 and 2019, respectively and $3.3 million and $2.9 million for the six months ended June 30, 2020 and 2019, respectively.

Costs related to filing and pursuing patent applications are expensed as incurred, as recoverability of such expenditures is uncertain. The Company includes all external costs related to the filing of patents on developments in Research, Development and Patents expenses. Such patent-related expenses totaled $0.1 million for each of the three months ended June 30, 2020 and 2019, respectively and $0.2 million for each of the six months ended June 30, 2020 and 2019, respectively.

Clinical Trial Accruals and Prepaid Expenses

Costs for preclinical studies, clinical studies and manufacturing activities are recognized as research and development expenses based on an evaluation of the progress by Company vendors towards completion of specific tasks, using data such as patient enrollment, clinical site activations or information provided to the Company by such vendors regarding their actual costs incurred. Payments for these activities are based on the terms of individual contracts and payment timing may differ significantly from the period in which the services are performed. The Company determines accrual estimates through reports from and discussions with applicable personnel and outside service providers as to the progress or state of completion of studies, or the services completed. The Company’s estimates of accrued expenses as of each balance sheet date are based on the facts and circumstances known at the time. Costs that are paid in advance of performance are deferred as a prepaid expense and amortized over the service period as the services are provided.

Impact of COVID-19 on the Company’s Business

The pandemic caused by an outbreak of a new strain of coronavirus (“COVID-19” or “the pandemic”) has resulted, and is likely to continue to result, in significant national and global economic disruption and may adversely affect the Company’s business. Although the pandemic resulted in a decrease in the number of patient visits at certain of the Company’s clinical trial sites, the Company expects this effect to be temporary. The Company has seen an increase in the number of patient visits compared to earlier in the pandemic and the Company continues to enroll patients in clinical trials. Throughout the pandemic, the Company has continued with routine clinical trial activities including executing new clinical trial agreements, negotiating budgets, institutional review board (IRB) approvals, site training, and other activities related to the initiation of new clinical trial sites. In addition, following the outbreak of the pandemic, the Company designed a clinical trial to evaluate MN-166 (ibudilast) for prevention of acute respiratory distress syndrome (ARDS) caused by COVID-19, which was based on positive results of a recently published study of MN-166 (ibudilast) in an animal model of ARDS. During the pandemic, the Company has been able to continue with routine regulatory activities. For example, the Company successfully submitted an Investigational New Drug Application (IND) for MN-166 (ibudilast) for prevention of Acute Respiratory Distress Syndrome (ARDS) which was accepted and is now open with the U.S. Food and Drug Administration (FDA). The Company was also informed by the FDA that the proposed clinical investigation of MN-166 (ibudilast) for the prevention of ARDS in patients with COVID-19 may proceed. Based on the Company’s current assessment, the Company does not expect a material negative impact on its clinical development plans, long-term development timeline or liquidity due to the worldwide spread of the COVID-19 virus. However, the Company is actively monitoring this situation and the possible effects on its financial condition, liquidity, operations, suppliers, industry, and workforce.

Use of Estimates

The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and the accompanying notes. Actual results could differ from those estimates.

Recent Accounting Pronouncements

In August 2018, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2018-13, Fair Value Measurement (Topic 820), which eliminates, adds and modifies certain disclosure requirements for fair value measurements. The modified standard eliminates the requirement to disclose changes in unrealized gains and losses included in earnings for recurring Level 3 fair value measurements and requires that changes in unrealized gains and losses be included in other comprehensive income for recurring Level 3 fair value measurements of instruments. The standard also requires the disclosure of the range and weighted average used to develop significant unobservable inputs and how weighted average is calculated for recurring and nonrecurring Level 3 fair value measurements. The amendment was effective for fiscal years beginning after December 15, 2019 and interim periods within that fiscal year with early adoption permitted. The Company adopted ASU 2018-13 on January 1, 2020 with no material impact on its consolidated financial statements.

Revenue Recognition

6 Months Ended

Jun. 30, 2020

Revenue From Contract With Customer [Abstract]

Revenue Recognition

2. Revenue Recognition

Revenue Recognition Policy

Revenues consist mainly of research and development services performed under a contract with a customer. The Company evaluates the separate performance obligation(s) under each contract, allocates the transaction price to each performance obligation considering the estimated stand-alone selling prices of the services and recognizes revenue upon the satisfaction of such obligations over time or at a point in time dependent on the satisfaction of one of the following criteria: (1) the customer simultaneously receives and consumes the economic benefits provided by the vendor’s performance (2) the vendor creates or enhances an asset controlled by the customer (3) the vendor’s performance does not create an asset for which the vendor has an alternative use, and the vendor has an enforceable right to payment for performance completed to date.

Kissei Pharmaceutical Co., Ltd

In October 2011, the Company entered into a collaboration agreement with Kissei Pharmaceutical Co., Ltd., (“Kissei”), to perform research and development services relating to MN-221 (bedoradrine) in exchange for a non-refundable upfront payment of $2.5 million. Under the terms of the agreement, the Company is responsible for all costs to be incurred in the performance of these services. The Company assessed the services in accordance with the authoritative guidance and concluded that the two studies to be performed under the agreement represented two separate performance obligations. The transaction price was allocated among the two studies that were deemed separate performance obligations based on the expected costs to be incurred for each obligation. Revenue is recognized proportional to the total costs expected for each performance obligation as incurred over the service period. The first study was completed in 2013 and the timing of the second study is undetermined as of June 30, 2020. The amount received from Kissei and allocated, net of the amount recorded as revenue, is included on the balance sheet as long-term deferred revenue and will be recognized as revenue as the remaining performance obligation is satisfied. No revenue was recognized for the three and six months ended June 30, 2020 and 2019 in connection with the collaboration agreement with Kissei.

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-URI http://asc.fasb.org/topic&trid=49130388

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130551-203045

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130556-203045

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130550-203045

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130558-203045

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

+ Details

Fair Value Measurements

6 Months Ended

Jun. 30, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

3. Fair Value Measurements

Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, a three-tier fair value hierarchy has been established, which prioritizes the inputs used in measuring fair value as follows:

Level 1:	Observable inputs such as quoted prices in active markets;

Level 2:	Inputs are quoted prices for similar items in active markets or quoted prices for identical or similar items in markets that are not active near the measurement date; and

Level 3:	Unobservable inputs due to little or no market data, which require the reporting entity to develop its own assumptions.

Cash equivalents, including money market accounts of $694,042 and $691,649 measured at fair value as of June 30, 2020 and December 31, 2019, respectively, are classified within Level 1.

Stock-based Compensation

6 Months Ended

Jun. 30, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-based Compensation

4. Stock-based Compensation

Stock Incentive Plans

In June 2013, the Company adopted the 2013 Equity Incentive Plan, or 2013 Plan, under which the Company may grant stock options, stock appreciation rights, restricted stock, restricted stock units and other awards to individuals who are then employees, officers, non-employee directors or consultants of the Company or its subsidiaries. The 2013 Plan is the successor to the Company’s Amended and Restated 2004 Stock Incentive Plan, or 2004 Plan. A total of 8,700,000 shares of common stock are reserved for issuance under the 2013 Plan. In addition, “returning shares” that may become available from time to time are added back to the plan. “Returning shares” are shares that are subject to outstanding awards granted under the 2004 Plan that expire or terminate prior to exercise or settlement, are forfeited because of the failure to vest, are repurchased, or are withheld to satisfy tax withholding or purchase price obligations in connection with such awards. Although the Company no longer grants equity awards under the 2004 Plan, all outstanding stock awards granted under the 2004 Plan will continue to be subject to the terms and conditions as set forth in the agreements evidencing such stock awards and the terms of the 2004 Plan. As of June 30, 2020, 2,833,135 shares remain available for future grants under the 2013 Plan.

The Company occasionally issues employee performance-based stock options, the vesting of which is based on a determination made by the board of directors as to the achievement of certain corporate objectives at the end of the performance period. The grant

date of such awards is the date on which the board of directors makes its determination. For periods preceding the grant date, the expense related to these awards is measured based on their fair value at each reporting date.

Stock Options

Options granted under the 2013 Plan and the 2004 Plan have terms of ten years from the date of grant unless earlier terminated and generally vest over a three or four year period. The exercise price of all options granted through June 30, 2020 and in 2019, was equal to the market value of the Company’s common stock on the date of grant.

A summary of stock option activity and related information as of June 30, 2020 is as follows:

	Number of Option Shares			Weighted Average Exercise Price
Outstanding at December 31, 2019		6,802,093		$	5.61
Granted		1,331,000			6.70
Exercised		(143,863	)		3.05
Cancelled		(379,843	)		9.17
Outstanding at June 30, 2020		7,609,387		$	5.67
Exercisable at June 30, 2020		6,285,887		$	5.45

Employee Stock Purchase Plan

Under the Company’s 2007 Employee Stock Purchase Plan (ESPP), 300,000 shares of common stock were originally reserved for issuance. In addition, the shares reserved automatically increase each year by a number equal to the lesser of: (i) 15,000 shares; (ii) 1% of the outstanding shares of common stock on the last day of the immediately preceding fiscal year; or (iii) such lesser amount as determined by the Board. The ESPP permits full-time employees to purchase common stock through payroll deductions (which cannot exceed 15% of each employee’s compensation) at the lower of 85% of fair market value at the beginning of the offering period or the end of each six-month offering period. The ESPP is considered a compensatory plan and the Company records compensation expense included in the Company’s statement of operations.

For the six months ended June 30, 2020, an aggregate of 1,979 shares were issued under the ESPP. As of June 30, 2020, there were 215,957 shares available for future issuance under the ESPP.

Compensation Expense

Stock-based compensation expense for stock option awards and ESPP shares are reflected in total operating expenses for each respective year.

The following table summarizes stock-based compensation expenses for the three and six months ended June 30, 2020 and 2019, respectively:

	Three months ended				Six months ended
	June 30,				June 30,
	2020		2019		2020		2019
Research, development and patents	$	349,294	$	540,591	$	511,991	$	1,333,648
General and administrative		797,860		1,301,923		1,231,541		3,208,366
Total stock-based compensation expense	$	1,147,154	$	1,842,514	$	1,743,532	$	4,542,014

The Company uses the Black-Scholes valuation model for determining the estimated fair value for stock-based awards granted to employees and stock purchased under the ESPP. The following table provides the assumptions used in the Black-Scholes valuation model used to estimate the fair value of options granted and stock purchased under the ESPP during the six months ended June 30, 2020 and 2019, and to estimate the fair value of performance-based stock options as of June 30, 2020 and 2019.

	Six months ended
	June 30, 2020		June 30, 2019
Stock Option assumptions:
Risk-free interest rate	0.29 - 1.68%		1.76 - 2.19%
Expected volatility of common stock	57.44 - 66.49%		61.9 - 62.58%
Dividend yield	0%		0%
Expected term (in years)	4.5 - 5.6		5.0 - 5.3
ESPP assumptions:
Risk-free interest rate	0.14%		2.46%
Expected volatility of common stock	81.70%		72.5%
Dividend yield	0.0%		0.0%
Expected term (in years)		0.5		0.5

As of June 30, 2020, there was $2.0 million of unamortized compensation cost related to unvested stock option awards which is expected to be recognized over a remaining weighted-average vesting period of 0.63 years, on a straight-line basis.

Stockholders' Equity

6 Months Ended

Jun. 30, 2020

Equity [Abstract]

Stockholders' Equity

5. Stockholders’ Equity

At-The-Market Issuance Sales Agreements

On May 22, 2015, the Company entered into an at-the-market issuance sales agreement (the “2015 ATM Agreement”) with MLV & Co. LLC (MLV), pursuant to which the Company could sell common stock through MLV from time to time up to an aggregate offering price of $30.0 million. Sales of the Company’s common stock through MLV, if any, were to be made by any method that is deemed to be an “at-the-market” equity offering as defined in Rule 415 promulgated under the Securities Act of 1933, as amended, including sales made directly on NASDAQ, on any other existing trading market for the common stock or to or through a market maker. MLV could also sell the common stock in privately negotiated transactions, subject to the Company’s prior approval. The Company agreed to pay MLV an aggregate commission rate of up to 4.0% of the gross proceeds of any common stock sold under this agreement. Proceeds from sales of common stock depended on the number of shares of common stock sold to MLV and the per share purchase price of each transaction.

The Company was not obligated to make any sales of common stock under the sales agreement and could terminate the sales agreement at any time upon written notice. On September 16, 2016, the Company amended the original sales agreement with MLV to also include FBR Capital Markets & Co. as a sales agent. The 2015 ATM Agreement was terminated on August 23, 2019.

On August 23, 2019, the Company entered into an at market issuance sales agreement (the “2019 ATM Agreement”) with B. Riley FBR, Inc. (B. Riley FBR) pursuant to which the Company may sell common stock through B. Riley FBR from time to time up to an aggregate offering price of $75.0 million. Sales of the Company’s common stock through B. Riley FBR, if any, will be made by any method that is deemed to be an “at-the-market” equity offering as defined in Rule 415 promulgated under the Securities Act of 1933, as amended, including sales made directly on NASDAQ, on any other existing trading market for the common stock or through a market maker. B. Riley FBR may also sell the common stock in privately negotiated transactions, subject to the Company’s prior approval. The Company agreed to pay B. Riley FBR an aggregate commission rate of up to 3.5% of the gross proceeds of any common stock sold under this agreement. Proceeds from sales of common stock will depend on the number of shares of common stock sold to B. Riley FBR and the per share purchase price of each transaction.

For the six months ended June 30, 2020 the Company generated net proceeds of $1.2 million under the 2019 ATM Agreement, on sales of 209,671 shares of the Company’s common stock at a weighted average price of $5.83 per share.

Net Loss Per Share

6 Months Ended

Jun. 30, 2020

Earnings Per Share [Abstract]

Net Loss Per Share

6. Net Loss Per Share

The Company computes basic net loss per share using the weighted average number of common shares outstanding during the period. Diluted net income per share is based upon the weighted average number of common shares and potentially dilutive securities (common share equivalents) outstanding during the period. Common share equivalents outstanding, determined using the treasury stock method, are comprised of shares that may be issued under the Company’s stock option agreements. Common share equivalents are excluded from the diluted net loss per share calculation if their effect is anti-dilutive.

Potentially dilutive outstanding securities excluded from diluted net loss per common share due to their anti-dilutive effect totaled 7,609,387 shares and 6,826,193 shares as of June 30, 2020 and 2019, respectively.

Subsequent Events

6 Months Ended

Jun. 30, 2020

Subsequent Events [Abstract]

Subsequent Events

7. Subsequent Events

At-The-Market Issuance

Subsequent to June 30, 2020 and through July 23, 2020, the Company sold 109,365 shares of common stock under the ATM Agreement at a weighted average price of $5.73 per share for net proceeds of $0.6 million.

Interim Financial Information (Policies)	6 Months Ended
Interim Financial Information (Policies)	Jun. 30, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (GAAP) for interim financial information and with the instructions of the Securities and Exchange Commission (SEC) on Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all the information and disclosures required by GAAP for complete financial statements. In the opinion of management, the consolidated financial statements include all adjustments necessary, which are of a normal and recurring nature, for the fair presentation of the Company’s financial position and of the results of operations and cash flows for the periods presented. The accompanying unaudited consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. These financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto for the year ended December 31, 2019 included in the Company’s Annual Report on Form 10-K filed with the SEC. The results of operations for the interim period shown in this report are not necessarily indicative of the results that may be expected for any other interim period or for the full year. The balance sheet at December 31, 2019 has been derived from the audited financial statements at that date but does not include all the information and footnotes required by GAAP for complete financial statements.
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of MediciNova, Inc. and its wholly owned subsidiaries. All intercompany transactions and balances are eliminated in consolidation.
Segment Reporting	Segment Reporting The Company operates in a single operating segment – the acquisition and development of small molecule therapeutics for the treatment of serious diseases with unmet medical needs.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents consist of cash and other highly liquid investments including money market accounts.
Research, Development and Patents	Research, Development and Patents Research and development costs are expensed in the period incurred. Research and development costs primarily consist of salaries and related expenses for personnel, facilities and depreciation, research and development supplies, licenses and outside services. Such research and development costs totaled $2.1 million and $1.4 million for the three months ended June 30, 2020 and 2019, respectively and $3.3 million and $2.9 million for the six months ended June 30, 2020 and 2019, respectively. Costs related to filing and pursuing patent applications are expensed as incurred, as recoverability of such expenditures is uncertain. The Company includes all external costs related to the filing of patents on developments in Research, Development and Patents expenses. Such patent-related expenses totaled $0.1 million for each of the three months ended June 30, 2020 and 2019, respectively and $0.2 million for each of the six months ended June 30, 2020 and 2019, respectively.
Clinical Trial Accruals and Prepaid Expenses	Clinical Trial Accruals and Prepaid Expenses Costs for preclinical studies, clinical studies and manufacturing activities are recognized as research and development expenses based on an evaluation of the progress by Company vendors towards completion of specific tasks, using data such as patient enrollment, clinical site activations or information provided to the Company by such vendors regarding their actual costs incurred. Payments for these activities are based on the terms of individual contracts and payment timing may differ significantly from the period in which the services are performed. The Company determines accrual estimates through reports from and discussions with applicable personnel and outside service providers as to the progress or state of completion of studies, or the services completed. The Company’s estimates of accrued expenses as of each balance sheet date are based on the facts and circumstances known at the time. Costs that are paid in advance of performance are deferred as a prepaid expense and amortized over the service period as the services are provided.
Impact of COVID-19 on the Company’s Business	Impact of COVID-19 on the Company’s Business The pandemic caused by an outbreak of a new strain of coronavirus (“COVID-19” or “the pandemic”) has resulted, and is likely to continue to result, in significant national and global economic disruption and may adversely affect the Company’s business. Although the pandemic resulted in a decrease in the number of patient visits at certain of the Company’s clinical trial sites, the Company expects this effect to be temporary. The Company has seen an increase in the number of patient visits compared to earlier in the pandemic and the Company continues to enroll patients in clinical trials. Throughout the pandemic, the Company has continued with routine clinical trial activities including executing new clinical trial agreements, negotiating budgets, institutional review board (IRB) approvals, site training, and other activities related to the initiation of new clinical trial sites. In addition, following the outbreak of the pandemic, the Company designed a clinical trial to evaluate MN-166 (ibudilast) for prevention of acute respiratory distress syndrome (ARDS) caused by COVID-19, which was based on positive results of a recently published study of MN-166 (ibudilast) in an animal model of ARDS. During the pandemic, the Company has been able to continue with routine regulatory activities. For example, the Company successfully submitted an Investigational New Drug Application (IND) for MN-166 (ibudilast) for prevention of Acute Respiratory Distress Syndrome (ARDS) which was accepted and is now open with the U.S. Food and Drug Administration (FDA). The Company was also informed by the FDA that the proposed clinical investigation of MN-166 (ibudilast) for the prevention of ARDS in patients with COVID-19 may proceed. Based on the Company’s current assessment, the Company does not expect a material negative impact on its clinical development plans, long-term development timeline or liquidity due to the worldwide spread of the COVID-19 virus. However, the Company is actively monitoring this situation and the possible effects on its financial condition, liquidity, operations, suppliers, industry, and workforce.
Use of Estimates	Use of Estimates The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and the accompanying notes. Actual results could differ from those estimates.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In August 2018, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2018-13, Fair Value Measurement (Topic 820), which eliminates, adds and modifies certain disclosure requirements for fair value measurements. The modified standard eliminates the requirement to disclose changes in unrealized gains and losses included in earnings for recurring Level 3 fair value measurements and requires that changes in unrealized gains and losses be included in other comprehensive income for recurring Level 3 fair value measurements of instruments. The standard also requires the disclosure of the range and weighted average used to develop significant unobservable inputs and how weighted average is calculated for recurring and nonrecurring Level 3 fair value measurements. The amendment was effective for fiscal years beginning after December 15, 2019 and interim periods within that fiscal year with early adoption permitted. The Company adopted ASU 2018-13 on January 1, 2020 with no material impact on its consolidated financial statements.
Revenue Recognition Policy	Revenue Recognition Policy Revenues consist mainly of research and development services performed under a contract with a customer. The Company evaluates the separate performance obligation(s) under each contract, allocates the transaction price to each performance obligation considering the estimated stand-alone selling prices of the services and recognizes revenue upon the satisfaction of such obligations over time or at a point in time dependent on the satisfaction of one of the following criteria: (1) the customer simultaneously receives and consumes the economic benefits provided by the vendor’s performance (2) the vendor creates or enhances an asset controlled by the customer (3) the vendor’s performance does not create an asset for which the vendor has an alternative use, and the vendor has an enforceable right to payment for performance completed to date.

Stock-based Compensation (Tables)

6 Months Ended

Jun. 30, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Option Activity and Related Information

A summary of stock option activity and related information as of June 30, 2020 is as follows:

	Number of Option Shares			Weighted Average Exercise Price
Outstanding at December 31, 2019		6,802,093		$	5.61
Granted		1,331,000			6.70
Exercised		(143,863	)		3.05
Cancelled		(379,843	)		9.17
Outstanding at June 30, 2020		7,609,387		$	5.67
Exercisable at June 30, 2020		6,285,887		$	5.45

Summary of Stock-based Compensation Expenses

The following table summarizes stock-based compensation expenses for the three and six months ended June 30, 2020 and 2019, respectively:

	Three months ended				Six months ended
	June 30,				June 30,
	2020		2019		2020		2019
Research, development and patents	$	349,294	$	540,591	$	511,991	$	1,333,648
General and administrative		797,860		1,301,923		1,231,541		3,208,366
Total stock-based compensation expense	$	1,147,154	$	1,842,514	$	1,743,532	$	4,542,014

Schedule of Assumptions Used in Estimating Fair Value of Options Granted, Stock Purchased Under ESPP and Performance-Based Stock Options

The following table provides the assumptions used in the Black-Scholes valuation model used to estimate the fair value of options granted and stock purchased under the ESPP during the six months ended June 30, 2020 and 2019, and to estimate the fair value of performance-based stock options as of June 30, 2020 and 2019.

	Six months ended
	June 30, 2020		June 30, 2019
Stock Option assumptions:
Risk-free interest rate	0.29 - 1.68%		1.76 - 2.19%
Expected volatility of common stock	57.44 - 66.49%		61.9 - 62.58%
Dividend yield	0%		0%
Expected term (in years)	4.5 - 5.6		5.0 - 5.3
ESPP assumptions:
Risk-free interest rate	0.14%		2.46%
Expected volatility of common stock	81.70%		72.5%
Dividend yield	0.0%		0.0%
Expected term (in years)		0.5		0.5

Interim Financial Information - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Quarterly Financial Information Disclosure [Abstract]
Research and development costs	$ 2.1	$ 1.4	$ 3.3	$ 2.9
Patent-related expenses	$ 0.1	$ 0.1	$ 0.2	$ 0.2

Revenue Recognition - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Oct. 31, 2011
Revenue Recognition Milestone Method [Line Items]
Deferred revenue related to research and development services	$ 1,694,163		$ 1,694,163		$ 1,694,163
Kissei Pharmaceutical Co., Ltd
Revenue Recognition Milestone Method [Line Items]
Deferred revenue related to research and development services						$ 2,500,000
Revenue relating to research and development services	$ 0	$ 0	$ 0	$ 0

Fair Value Measurements - Additional Information (Detail) - USD ($)	Jun. 30, 2020	Dec. 31, 2019
Level 1 \| Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents, fair value	$ 694,042	$ 691,649

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Dec. 31, 2017	Jun. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved, description	shares reserved automatically increase each year by a number equal to the lesser of: (i) 15,000 shares; (ii) 1% of the outstanding shares of common stock on the last day of the immediately preceding fiscal year; or (iii) such lesser amount as determined by the Board.
Employee stock purchase plan offering period	6 months
Shares issued under ESPP	1,979
Unamortized compensation cost	$ 2.0
Unamortized compensation cost, vesting period	7 months 17 days
2007 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	215,957	300,000
Percentage of employee compensation for purchase of common stock under ESPP	15.00%
Common stock fair market value, percentage	85.00%
Maximum \| 2007 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in shares reserved for issuance	15,000
Increase in shares reserved for issuance as percentage of outstanding shares	1.00%
2013 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance			8,700,000
Shares available for future grant	2,833,135
2013 Plan \| Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted expiration term	10 years
2013 Plan \| Stock Option \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option, vesting period	3 years
2013 Plan \| Stock Option \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option, vesting period	4 years
2004 Plan \| Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted expiration term	10 years
2004 Plan \| Stock Option \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option, vesting period	3 years
2004 Plan \| Stock Option \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option, vesting period	4 years

Summary of Stock Option Activity and Related Information (Detail) - $ / shares	6 Months Ended
	Jun. 30, 2020
Number of Option Shares
Stock Options, Beginning Balance	6,802,093
Stock Options, Granted	1,331,000
Stock Options, Exercised	(143,863)
Stock Options, Cancelled	(379,843)
Stock Options, Ending Balance	7,609,387
Stock Options, Exercisable at June 30, 2020	6,285,887
Weighted Average Exercise Price, Beginning Balance	$ 5.61
Weighted Average Exercise Price, Granted	6.70
Weighted Average Exercise Price, Exercised	3.05
Weighted Average Exercise Price, Cancelled	9.17
Weighted Average Exercise Price, Ending Balance	5.67
Weighted Average Exercise Price, Exercisable at June 30, 2020	$ 5.45

Summary of Stock-based Compensation Expenses (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 1,147,154	$ 1,842,514	$ 1,743,532	$ 4,542,014
Research, Development and Patents
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	349,294	540,591	511,991	1,333,648
General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 797,860	$ 1,301,923	$ 1,231,541	$ 3,208,366

Schedule of Assumptions Used in Estimating Fair Value of Options Granted, Stock Purchased Under ESPP and Performance-Based Stock Options (Detail)	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Employee Stock Purchase Plan
Weighted-average assumptions for stock options and ESPP
Risk-free interest rate	0.14%	2.46%
Expected volatility of common stock	81.70%	72.50%
Dividend yield	0.00%	0.00%
Expected term (in years)	6 months	6 months
Stock Option
Weighted-average assumptions for stock options and ESPP
Dividend yield	0.00%	0.00%
Stock Option \| Minimum
Weighted-average assumptions for stock options and ESPP
Risk-free interest rate	0.29%	1.76%
Expected volatility of common stock	57.44%	61.90%
Expected term (in years)	4 years 6 months	5 years
Stock Option \| Maximum
Weighted-average assumptions for stock options and ESPP
Risk-free interest rate	1.68%	2.19%
Expected volatility of common stock	66.49%	62.58%
Expected term (in years)	5 years 7 months 6 days	5 years 3 months 18 days

Stockholders' Equity - Additional Information (Detail) - USD ($)			6 Months Ended
	Aug. 23, 2019	May 22, 2015	Jun. 30, 2020
Common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock, net of offering costs (in shares)			209,671
2019 at-the-market issuance sales agreement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock purchase agreement, net proceeds			$ 1,200,000
Weighted Average \| Common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares purchase & equity issuance, price per share amount			$ 5.83
MLV \| 2015 at-the-market issuance sales agreement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Sales commission as a percentage of gross proceeds		4.00%
Agreement termination date			Aug. 23, 2019
MLV \| Maximum \| 2015 at-the-market issuance sales agreement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock purchase agreement, aggregate amount of common stock agreed to be purchased		$ 30,000,000.0
B. Riley FBR \| 2019 at-the-market issuance sales agreement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Sales commission as a percentage of gross proceeds	3.50%
B. Riley FBR \| Maximum \| 2019 at-the-market issuance sales agreement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock purchase agreement, aggregate amount of common stock agreed to be purchased	$ 75,000,000.0

Net Loss Per Share - Additional Information (Detail) - shares	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Potentially dilutive outstanding securities excluded from diluted net loss per common share	7,609,387	6,826,193

Subsequent Events - Additional Information (Detail) - ATM Agreement - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	6 Months Ended
	Jul. 23, 2020	Jun. 30, 2020
Subsequent Event [Line Items]
Proceeds from Issuance		$ 1.2
Subsequent Event
Subsequent Event [Line Items]
Shares of common stock sold	109,365
Weighted average share price	$ 5.73
Proceeds from Issuance	$ 0.6