Developing medicines to treat addictions and overdose

NASDAQ: OPNT August 2021 Forward-Looking Statements

This presentation contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. These forward-looking statements relate to future events or our future financial performance and involve known and unknown risks, uncertainties and other factors that may cause our or our industry’s actual results, levels of activity, performance or achievements to be materially different from any future results, levels of activity, performance or achievements expressed, implied or inferred by these forward-looking statements. In some cases, you can identify forward-looking statements by terminology such as “may,” “will,” “should,” “could,” “would,” “expects,” “plans,” “intends,” “anticipates,” “believes,” “estimates,” “predicts,”

“projects,” “potential,” or “continue” or the negative of such terms and other comparable terminology. These forward-looking statements are only predictions based on our current expectations and projections about future events. You should not place undue reliance on these forward-looking statements. Actual events or results may differ materially. In evaluating these forward-looking statements, you should specifically consider various factors. These and other factors may cause our actual results to differ materially from any forward-looking statement. We undertake no obligation to update any of the forward-looking statements after the date of this presentation to conform those statements to reflect the occurrence of unanticipated events, except as required by applicable law.

Page I 2 Opiant is leading a new wave of innovation in addiction and overdose

Developed NARCAN® Nasal Spray, which is credited with reducing opioid overdose deaths. Our vision: Advancing investigational OPNT003 nasal nalmefene for opioid A world where addictions overdose – particularly well suited for synthetic opioids, incl. Fentanyl. are recognized as Robust pipeline in Opioid Overdose, Alcohol Use Disorder, Acute of the brain and Overdose, Opioid Use Disorder. treated like other chronic medical conditions. Financial support and collaboration of multiple U.S. government agencies including NIDA, BARDA.

$48.5M cash and cash equivalents (June 30, 2021).

$28.9M projected royalties from NARCAN® for the full-year 2021.

Page I 3 Health burden of addiction and overdose are an urgent call to action

Death rates from alcohol and continue to climb -- and worsening during COVID-19

August 14, 2020

October 25, 2019

January 10, 2020

September 16, 2019

Source: Social Capital Project analyses of CDC data.

Page I 4 Pipeline with a strategic focus to transform in addiction and overdose

Pre- FDA Indication Product Candidate / Regulatory Pathway Phase 1 Phase 2 Phase 3 NDA Partner clinical Approval

Opioid Overdose NARCAN® Nasal Spray / 505(b)(2)

OPNT003* Opioid Overdose Nalmefene Nasal Spray / 505(b)(2)

OPNT002 Alcohol Use Opioid Antagonist Nasal Spray / Disorder 505(b)(2)

Acute OPNT004** Cannabinoid Drinabant (CB-1 Antagonist) Overdose

OPNT005 Opioid Use Heroin Vaccine: hapten + liposome Disorder adjuvant

*OPNT003 has financial support from the National Institute on Drug Abuse (“NIDA”) and the Biomedical Advanced Research and Development Authority (“BARDA”)

*Cooperative research and development agreement with the National Center for Advancing Translational Sciences (“NCATS”) to formulate OPNT004 for human studies in Acute Cannabinoid Overdose

Page I 5 Accomplished leadership team combines extensive addiction, CNS drug development and commercial experience

Roger Crystal, MD, MRCS, MBA CEO

Phil Skolnick, PhD, DSc (hon) CSO

David O’Toole, CPA CFO

Mark Ellison, PhD Chief Development Officer

Brian Gorman, JD EVP Corporate Development and General Counsel

Matthew Ruth Chief Commercial Officer

Page I 6 OPNT003

Nasal Nalmefene for Opioid Overdose Opioid overdose remains a public health crisis, dramatically heightened as synthetic opioids such as fentanyl drive up overdose deaths

Number of opioid overdose deaths in the U.S.

80000 Phase 3: synthetic opioids 70000 Synthetic opioids such as fentanyl present in 60000 over three quarters of opioid overdose deaths 50000

40000 Phase 2: heroin 30000

20000 Heroin main driver of opioid overdose deaths

10000 Phase 1: painkillers 0 2015 2016 2017 2018 2019 2020 Opioid painkillers drive overdose deaths All opioids Synthetic opioids incl. fentanyl Heroin Rx opioids

Provisional Data, CDC.

Page I 8 Fentanyl leads wave of highly potent synthetic opioids, NIH calling for ‘stronger, longer-acting formulations of antagonists…’

Fentanyl: America’s new health crisis 2020 and beyond… • 50x stronger than heroin and cheaper

• Longer duration of action than heroin (>7 hours vs. 1-2 hours) • Fentanyl and related compounds • Fentanyl analogues even stronger, e.g. carfentanil laced into other illicit drugs such as • Synthetic opioid surge is fueled by multiple sources cocaine – often without the user knowing • Greater presence of more potent opioids such as carfentanil • Fentanyl being made within the USA – ‘Breaking Bad’

Lethal amounts of • Growing concern over the use of heroin, fentanyl and ‘supercharged’ fentanyl in a chemical attack carfentanil 2018 Provisional Data, CDC. Source: NYT 7-17-19

Page I 9 Fentanyl’s potency can require multiple and continued doses of for rescue, creating an increasing drain on health-care resources across the U.S.

Fentanyl overdose may require a more potent, faster onset, and longer-duration opiate antagonist than naloxone

• Opioid antagonists compete with opioids for µ opioid receptors; a higher affinity at the mu opioid favors a successful rescue

• The plasma half-life of naloxone is 1 to 2 hours; fentanyl has a half-life of 7 to 8 hours – this longer duration can lead to subsequent overdose from renarcotization

• The rapid onset of fentanyl shortens the window for a rescue , so a more rapid treatment onset favors a successful rescue

Page I 10 OPNT003, nasal nalmefene: A potential solution to the evolving opioid overdose crisis

Characteristics that make OPNT003 potentially superior

OPNT003 Naloxone (3mg) (4mg) Increased affinity at the μ 1.01 5.41 opioid receptors

Longer half-life 112 2.083

Faster rate of absorption 15 minutes2 30 minutes3

1 3 Ki values were estimated using [ H]alvimopan binding to cloned human m opioid receptors (Cassel, et al., 2005). The ~5-fold higher affinity of nalmefene compared to naloxone is consistent with both Ki values obtained (0.13 and 0.62 nM, respectively) 3 using [ H]DAMGO as a radioligand in monkey brain membranes (Emmerson, et al., 1994) and pA2 values of 9.38 and 8.51, respectively, in functional assays using guinea pig ileum and mouse vas deferens (Toll, et al., 1998). 2Data on file: NCT04759768 3 Data from FDA, 2015 (https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/208411lbl.pdf)

Page I 11 Pharmacokinetic data of OPNT003 nasal nalmefene demonstrates rapid absorption and high concentration critical to a successful rescue

1 Confirmatory Pharmacokinetic Study 1

2 Nasal nalmefene achieved significantly higher plasma concentrations compared to injection (P<0.0001)

• ~15 minutes to achieve maximum plasma concentrations (Tmax)

• Maximum plasma concentration higher than 4 mg IN naloxone (Cmax)

1. 2Data on file: NCT04759768 2. Krieter P, Chiang N, Gyaw S, Skolnick P, Crystal R, Keegan F, Aker J, Beck M, Harris J. Pharmacokinetic Properties and Human Use Characteristics of an FDA-Approved Intranasal Naloxone Product for the Treatment of Opioid Overdose. J Clin Pharmacol. 2016 Oct;56(10):1243-53. doi: 10.1002/jcph.759. Epub 2016 Jun 10. PMID: 27145977.

Page I 12 Pharmacodynamic study underway assessing OPNT003 compared to nasal naloxone in reversing respiratory depression produced by synthetic opioid

• Two-part trial across ~56 healthy subjects studying the pharmacodynamic effects of nasal nalmefene compared to nasal naloxone

• Primary Endpoint: Change in respiratory volume from opioid induced breathing suppression

• Anticipate results in Q4 2021

ClinicalTrials.gov identifier (NCT number): NCT04828005; https://clinicaltrials.gov/ct2/show/NCT04828005?term=opiant&draw=2&rank=1

Page I 13 FDA has confirmed a 505(b)(2) pathway OPNT003, with key regulatory activities funded by NIDA and BARDA

1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q 2021 2021 2021 2021 2022 2022 2022 2022

Confirmatory PK PD NDA Potential Commercial Pharmacokinetic data data Filing for FDA launch (“PK”) study approval

Pharmacodynamic (“PD”) study

Note: timeline events based on Company’s expectations as of March 2020

Page I 14 Disciplined commercial approach can unlock significant value for OPNT003 driven by prevalence of opioid overdoses and substantial government funding

Today: NARCAN® Nasal Spray sales projected at $325M in 2021, up from ~$25M in 20161

Target markets: Retail Funded by: Public Interest Sector OPNT003SAMSHA • Emergency medical services (EMS) • State Opioid Response and Block Grants • law enforcement (local and federal) • Significant added government support • Fire Departments • Possible proceeds from settlement • Community

Retail Sector Payors Driven by co-prescribing legislation now • NARCAN® Nasal Spray minimal co-pay present in 12 states, and Pharmacy for almost all payors Standing Orders – in all states

1. Based on Adapt Pharma revenue (2016) and Emergent Biosolutions NARCAN® Nasal Spray expected net sales in 2021

Page I 15 OPNT002

Nasal for Alcohol Use Disorder (AUD) Despite alcohol abuse rates increasing, existing medication is poorly tolerated and requires specialist prescribing – we need better medication for AUD

Limitations of current treatments:

~16.3 million have AUD Treatment for alcohol dependence often involves Addressable Market for OPNT002 abstinence-based approaches

Low adherence for existing medication – high relapse 1.4 million rates People seeking treatment

Commercial assessment:

400,000 More effective and accessible pharmacotherapy can People receiving vastly increase the number of patients taking treatment medication leading to improved outcomes.

* Diagnostic and Statistical Manual

Page I 17 OPNT002 has the potential to address the challenges of current AUD medicines by quickly reducing the pleasure effects from drinking

OPNT002 blocks endorphins Nasal spray delivers rapid FDA considers no heavy released by alcohol onset of action drinking days an endpoint

Breaks the connection the Suitable for use ‘as needed’ Reducing drinking from brain has made between when a patient anticipates very high to moderate levels drinking and pleasure drinking or is craving can reduce long-term alcohol mortality and overall burden

Page I 18 Rapid nasal absorption of OPNT002 vs oral naltrexone, ensures that the maximum amount of drug is present when binge drinking starts

• Cmax is ~50% higher with Naltrexone Blood Levels Oral vs Nasal vs Nasal with Intravail® OPNT002 than oral naltrexone along with a Tmax of ~12 minutes and short half life – absorption of oral naltrexone is minimal at 5 to

10 minutes Oral naltrexone

• Higher naltrexone levels with OPNT002, Nasal naltrexone with IntravailTM OPNT002 has the potential to TM block mu and delta-opioid Nasal naltrexone with Saline receptors, which both contribute to naltrexone level with Vivitrol® in steady state the desire to drink – oral naltrexone does not increase plasma enough to target the delta-

opioid receptor Krieter et al; J Clin Pharm; 2019; 00(0); 1-11. Dunbar et al; Alcohol Clin Exp Res, Vol 30, No 3, 2006: pp 480–490

Page I 19 OPNT002 Clinical Development Program; 505(b)(2) regulatory pathway confirmed by FDA

Phase 2 Study details Sequential Parallel Comparison Study Design for the Ph 2 trial of OPNT002 to mitigate the high placebo response common in AUD • Randomized 300-participant trials double-blind, placebo- controlled • Determine whether OPNT002 reduces heavy drinking in patients as measured by a change in the World Health Organization drinking risk levels • Features a Sequential Parallel Comparison Study Design (SPCD) to reduce placebo response

Page I 20 OPNT004 (drinabant)

CB-1 Antagonist for Acute Cannabinoid Overdose Medical emergencies involving Acute Cannabinoid Overdose have become significantly more prevalent – time is ripe for an ACO reversal product

>1 million Expected rise ACO annual in ACO cases with Emergency Room continued (ER) visits legalization

• Acute Cannabinoid Overdose (ACO) is caused by excessive consumption of THC - primarily edibles and synthetics (e.g., K2, Spice)

• Patients arrive at the ER very unwell: comatose state or excited delirium or maybe psychotic - symptoms and severity depend on quantity, potency and type of cannabinoid

Page I 22 Opiant is developing OPNT004 - drinabant, a CB-1 antagonist licensed from , for the emergency treatment of ACO

In a Sanofi study on 36 subjects, oral drinabant blocked subjective and Proof of objective psychological and physiological effects of inhaled THC (incl. principle data euphoria)

Extensive safety database with oral drinabant, generated by Sanofi: Phase Safety Database 1 and 2 studies on more than 700 subjects for up to 24 weeks

Reformulate drinabant as an injection more suitable for emergency room setting Next Steps - IND enabling activities funded by NCATs division of NIH Demonstrate ability of drinabant to reverse the effects of THC

Page I 23 Financials Financial highlights

Quarter ended Quarter ended Year ended June 30, 2021 March 31, 2021 December 31, 2020 Cash Balance $48.5 million $50.6 million $48.3 million Debt $20 million $20 million $20 million Revenue $11.3 million $6.4 million $29.6 million Common Shares 4.3 million 4.3 million 4.3 million Outstanding Fully Diluted Share Count 7.8 million Strong Financial Position

• Cash of $48.5 million as of June 30, 2021 • 2021 royalty stream projected at approximately $28.9 million • NIDA grant of $7.4 million for development of OPNT003 • BARDA contract of up to $8.1 million funding OPNT003 development as a counter-measure against a chemical attack • Convertible debt financing (12/10/20); up to $50 million in three tranches; first tranche of $20 million funded 12/10/20; Up to half of outstanding loan can be converted into Opiant Common stock at $19.64 per share.

Page I 25 NARCAN® Nasal Spray is licensed to Emergent BioSolutions and Opiant receives royalties

Potential annual payments to Opiant based on Schedule of Annual Royalty Rates Emergent BioSolutions’s 2021 revenue guidance Net Sales Royalty Rate Emergent BioSolutions provided guidance of $305 million Up to $50M 6% to $325 million net sales for calendar year 2021 which would provide Opiant with: $50M to $75M 7.5% - Royalties of approximately $27 million to $29 million $75M to $100M 9% If net sales in 2021 were $325 million, Opiant would have $100M to $200M 10% royalties of approximately $28.9 million.

Over $200M 12%

Page I 26 Summary Contact us:

Harnessing medical innovation to combat Ben Atkins addiction and overdose with anticipated NDA filing Vice President Investor Relations for lead program in opioid overdose; Ph 2 clinical [email protected] study for Alcohol Use Disorder; IND enabling activities for Acute Cannabinoid Overdose.

We have the financial support and collaboration of multiple government agencies.

Industry leading team funded for success with $48.5 million in cash position and ~ $28.9 million projected annual revenue from NARCAN® nasal spray royalties. NASDAQ: OPNT