Exhibit 99.1

April 24, 2025

Indivior Announces Results for the First Quarter Ended March 31, 2025; FY 2025 Guidance Unchanged

The “Company” refers to Indivior PLC and its consolidated subsidiaries.

“Our first quarter results were in line with our planning assumptions and consistent with our FY 2025 outlook,” said Mark Crossley, Chief Executive Officer. “Net revenue performance was primarily impacted by intensified generic competition for SUBOXONE Film in the U.S. and the discontinuation of PERSERIS in the prior year. SUBLOCADE continued to grow solidly year-over-year in organized health systems (OHS), but as expected, net revenue declined modestly due to near-term impacts from funding gaps among certain justice system customers. We expect to generate SUBLOCADE growth again in the second half of FY 2025 from our increased marketing investments and the important FDA-approved label changes that further improve the patient and physician experience.”

“As previously announced, I will be stepping down as CEO of Indivior next month. It has been an honor to lead the Company over the past five years and I would like to add a personal note of thanks to all my colleagues for tirelessly pursuing our goal of making meaningful recovery from addiction humanly possible. The opioid epidemic remains one of the greatest health challenges of our time and our mission and vision are as relevant as ever. I believe that our team, under Joe Ciaffoni’s leadership, will deliver the next chapter of growth and value creation for Indivior.”

Q1 2025 Product Highlights

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SUBLOCADE Label Update

On February 24, 2025, the FDA approved label changes for SUBLOCADE, including a rapid initiation protocol and alternative injection sites, which further improve the patient and physician experience and mark an advancement in the treatment of moderate to severe opioid use disorder (OUD). Key SUBLOCADE label changes include:

Pipeline Update

Share Repurchase Program

Indivior’s fourth $100m share repurchase program was completed on January 31, 2025. Under this program, the Company repurchased and canceled 9,415,726 Indivior ordinary shares at a weighted average purchase price of $10.62.

FY 2025 Guidance Unchanged

The Company’s guidance for FY 2025 under U.S. GAAP is unchanged.

Guidance assumes no material change in exchange rates for key currencies compared with FY 2024 average rates, notably USD/GBP and USD/EUR. Guidance also assumes no material change to Medicaid eligibility policy and/or other changes to Federal funding levels due to executive actions. Guidance also does not include any potential impacts from tariffs imposed by the U.S. government or any retaliatory tariffs that may be imposed by other countries.

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U.S. OUD Market Update

In Q1 2025, U.S. BMAT grew mid-single digits in volume terms. The Company continues to expect long-term U.S. growth to be sustained in the mid- to high-single digit percentage range due to increased overall awareness of the opioid epidemic and approved treatments and ongoing destigmatization efforts. Regulatory and legislative actions are also expected to increase access to BMAT treatments.

Financial Performance in Q1 2025

Total NR in Q1 2025 decreased 6% to $266m (Q1 2024: $284m) at actual exchange rates (5% decrease at constant exchange rates1).

U.S. NR decreased 8% in Q1 2025 to $222m (Q1 2024: $241m). In Q1 2025, U.S. SUBLOCADE NR decreased 3% to $163m (Q1 2024: $168m). The decrease in U.S. NR was primarily driven by the decline in SUBOXONE Film due to intensified generic competition that resulted in lower oral BMAT market share and lower pricing. The decline in PERSERIS (risperidone) extended release injection NR also contributed to the decline in U.S. NR due to discontinuation of promotion for the treatment in July 2024. SUBLOCADE NR was modestly lower year-over-year as described above.

Rest of the World NR increased 3% at actual exchange rates in Q1 2025 to $44m (Q1 2024: $42m; +1% at constant exchange rates1). In both periods, positive contributions from new products (SUBLOCADE / SUBUTEX® Prolonged Release and SUBOXONE Film) were partially offset by ongoing generic erosion of the legacy SUBUTEX (buprenorphine) tablet business. In Q1 2025, SUBLOCADE / SUBUTEX Prolonged Release NR increased $1m to $13m (Q1 2024: $12m) at actual exchange rates.

Gross margin in Q1 2025 was 83% (Q1 2024: 87%). The year-over-year decline primarily reflects favorable manufacturing variances for SUBLOCADE inventory sold in the same year-ago quarter.

SG&A expense in Q1 2025 was $132m (Q1 2024: $143m). Non-GAAP SG&A expense in Q1 2025 decreased 8% to $130m (non-GAAP Q1 2024: $142m) and primarily reflects benefits from streamlining actions taken in 2024, including narrowing the Company’s commercial focus on OUD treatments and discontinuing PERSERIS in July 2024. Q1 2025 SG&A expense also benefited from a low to mid-single digit $ million change in estimate related to Indivior’s share of the Branded Fee.

R&D expense in Q1 2025 was $22m (Q1 2024: $28m) and decreased 19% reflecting the Company’s actions to refocus its development pipeline on its Phase 2 OUD assets (INDV-2000 and INDV-6001).

Operating income was $66m in Q1 2025 (Q1 2024: $75m). The change reflects lower NR and higher cost of sales, partially offset by decreased operating expenses (SG&A and R&D combined).

After excluding non-GAAP adjustments of $3m and $2m in Q1 2025 and Q1 2024, respectively, Q1 2025 non-GAAP operating income decreased 10% to $69m (Q1 2024: $76m). The decrease primarily reflects the drivers discussed above.

Net interest expense was $7m in Q1 2025 (Q1 2024: $2m) reflecting the Company’s new borrowing secured in Q4 2024.

Tax expense was $11m in Q1 2025, resulting in an effective tax rate of 19% (Q1 2024: $11m, effective rate 16%). Both periods benefited from U.K. innovation deductions and intragroup financing transactions. In Q1 2025, this benefit was partially offset by a U.K. global minimum top-up tax. In Q1 2024, the Company recognized a share-compensation excess tax benefit. This excess tax benefit is excluded from the Company’s non-GAAP results.

Net income in Q1 2025 was $47m and non-GAAP net income was $51m (Q1 2024 net income: $61m, non-GAAP net income: $57m). The decline in net income primarily reflects lower NR and higher net interest expense, partly offset by lower operating expenses (SG&A and R&D combined).

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Diluted earnings per share in Q1 2025 were $0.38 and non-GAAP diluted earnings per share were $0.41 (Q1 2024: $0.45 diluted earnings per share and non-GAAP diluted earnings per share of $0.42). The modest decrease in non-GAAP diluted earnings per share in Q1 2025 includes the impact of the lower number of ordinary shares outstanding as a result of the Company’s share repurchase programs.

Balance Sheet & Cash Flow

Cash and investments totaled $400m at the end of Q1 2025, an increase of $53m versus $347m at the end of 2024. The increase was due to a combination of cash generated by operations and reduced net working capital due to the late receipt of government rebate invoices totaling approximately $100m, as reflected in the increase in Accrued Rebates and Product Returns on the balance sheet. These benefits were partially offset by litigation settlement payments of $65m.

Cash provided by operating activities in Q1 2025 was $75m (Q1 2024 cash used in operating activities: $37m), reflecting cash from operations and the late receipt of government rebate invoices, partly offset by litigation settlement payments. Cash used in operations in Q1 2024 reflected litigation settlement payments, partly offset by cash from operations.

Cash used in investing activities in Q1 2025 was $5m (Q1 2024 cash provided by investing activities: $25m) primarily reflecting capital expenditures in Q1 2025. Cash provided by investing activities in 2024 was driven by maturities of investment securities.

Cash used in financing activities in Q1 2025 was $17m (Q1 2024: $56m) reflecting lower cash outflows in Q1 2025 for share repurchases and net settlement of equity awards partially offset by higher repayments under the new debt facility.

Revision to Previously Issued Financial Statements

Indivior has revised its previously issued financial statements to correct the methodology used to accrue for the Company’s share of the annual U.S. fee imposed on drug manufacturers (the ‘Branded Fee’). This resulted from an immaterial overstatement of SG&A of $6m in 2024, $4m in 2023, $4m in 2022, and $2m before 2022. The adjustments increase operating income and impact the quarters evenly over the respective year. The cumulative impact to Accounts Payable and Accrued Expenses at December 31, 2024 was $16m.

The discussion of financial performance and the financial statements included in this announcement reflect the revised results for Q1 2024. The revised financial statements for the impacted periods noted will be included in the Company’s Form 10-Q as of March 31, 2025.

Webcast Details

A live webcast presentation will be held on April 24, 2025, at 13:00 GMT (8:00 am EDT). The details are below. Materials will be available on the Company’s website prior to the event at www.indivior.com. Please copy and paste the below web links into your browser.

The webcast link is: https://edge.media-server.com/mmc/p/yn37cxqk

Participants may access the presentation telephonically by registering with the following link (please cut and paste into your browser):

https://register-conf.media-server.com/register/BI4482694d7c294502b6a4dedd62e88c5b

(Registrants will have an option to be called back directly immediately prior to the call or be provided a call-in # with a unique pin code following their registration)

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For Further Information

This announcement does not constitute an offer to sell, or the solicitation of an offer to subscribe for or otherwise acquire or dispose of shares in the Company to any person in any jurisdiction to whom it is unlawful to make such offer or solicitation.

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About Indivior

Indivior is a global pharmaceutical company working to help change patients’ lives by developing medicines to treat opioid use disorder (OUD). Our vision is that all patients around the world will have access to evidence-based treatment for OUD and we are dedicated to transforming OUD from a global human crisis to a recognized and treated chronic disease. Building on its global portfolio of OUD treatments, Indivior has a pipeline of product candidates designed to expand on its heritage in this category. Headquartered in the United States in Richmond, VA, Indivior employs over 1,000 individuals globally and its portfolio of products is available in over 30 countries worldwide. Visit www.indivior.com to learn more. Connect with Indivior on LinkedIn by visiting www.linkedin.com/company/indivior.

Non-GAAP Financial Measures

This announcement includes financial measures that are not measures defined by US GAAP, such as non-GAAP selling, general and administrative expenses, non-GAAP operating income, non-GAAP net income and non-GAAP diluted earnings per share. These non-GAAP financial measures are not a substitute for, or superior to, results presented in accordance with US GAAP. Non-GAAP results as presented by the Company are not necessarily comparable to similarly titled measures used by other companies. As a result, these performance measures should not be considered in isolation from, or as a substitute analysis for, the Company’s results as reported in accordance with US GAAP. Management performs a quantitative and qualitative assessment to determine if an item should be considered for adjustment.

Management may use the Company’s non-GAAP financial measures to better understand trends in the business and these non-GAAP financial measures may be useful to investors. Non-GAAP financial measures adjust for non-recurring items and other items representing significant expenses or income that we believe do not reflect the Company’s ongoing operations or the adjustment of which may help with the comparison to prior periods. Non-recurring items and other adjustments are excluded from non-GAAP financial measures consistent with the internal reporting provided to management and the Directors. Examples of such items could include income or restructuring and related expenses from the reconfiguration of the Company’s activities and/or capital structure, impairment of current and non-current assets, gains and losses from the sale of intangible assets, certain costs arising as a result of significant and non-recurring regulatory and litigation matters, and certain tax related matters.

We have not provided the forward-looking U.S. GAAP equivalents for certain forward-looking non-U.S. GAAP metrics as a result of the uncertainty and potential variability of reconciling items. Accordingly, the Company has relied upon the exception in item 10(e)(1)(i)(B) of Regulation S-K to exclude such reconciliations, as the reconciliations of these non-U.S. GAAP guidance metrics to their corresponding U.S. GAAP equivalents are not available without unreasonable effort.

Columns and rows within financial tables may not foot due to rounding. Percentages and per share data have been calculated using actual, non-rounded figures.

Important Cautionary Note Regarding Forward-Looking Statements

This announcement contains certain statements that are forward-looking. Forward-looking statements include, among other things, express and implied statements regarding: the Company’s financial guidance including revenue, operating, and gross margins for 2025 and its medium- and long-term growth outlook; expected future growth and expectations for sales levels for particular products, and expectations regarding the future impact of factors that have affected sales in the past; expected operational savings and expected benefits from our reinvestment efforts; assumptions regarding expected changes in market share and expectations regarding the extent and impact of competition; assumptions regarding future exchange rates; expected timing of our previously-announced CEO transition; our expectations that we can reach a final settlement related to the provision we recorded regarding opioid litigation (including the MDL) brought by certain municipalities and tribal nations and the material terms and conditions of the final settlement agreement, including the ultimate timing and structure of payments and product distribution, injunctive relief, and scope of releases; expected growth in the number of BMAT treatments administered in the U.S., growing normalization of medically assisted treatment for opioid use disorder, and expanded access to treatment; our product development pipeline and potential future products, including the timing of clinical trials, expectations regarding regulatory approval of such product candidates, the timing of such approvals, and the timing of potential commercial launch of such products or product candidates, and eventual annual revenues of such future products; and other statements containing the words “believe,” “anticipate,”

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“plan,” “expect,” “intend,” “estimate,” “forecast,” “strategy,” “target,” “guidance,” “outlook,” “potential,” “project,” “priority,” “may,” “will,” “should,” “would,” “could,” “can,” “outlook,” the negatives thereof, and variations thereon and similar expressions. By their nature, forward-looking statements involve risks and uncertainties as they relate to events or circumstances that may or may not occur in the future.

Actual results may differ materially from those expressed or implied in these forward-looking statements due to a number of factors, including: lower than expected future sales of our products; greater than expected impacts from competition; failure to achieve market acceptance of OPVEE; unanticipated costs including the effects of potential tariffs and potential retaliatory tariffs; whether we are able to identify efficiencies and fund additional investments that we expect to generate increased revenues, and the timing of such actions; and litigants with whom we are otherwise unable or unwilling to agree to final terms, or who choose to “opt out” of proposed settlements. For additional information about some of the risks and important factors that could affect our future results and financial condition, see “Risk Factors” in Indivior’s Annual Report on Form 10-K filed March 3, 2025 and our other filings with the U.S. Securities and Exchange Commission.

We have based the forward-looking statements in this report on our current expectations and beliefs concerning future events. Forward-looking statements contained in this report speak only as of the day they are made and, except as required by law, we undertake no obligation to update or revise any forward-looking statement, whether due to new information, future developments or otherwise.

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Indivior PLC

(Amounts in millions, except per share data and percentages)

(Unaudited)

Consolidated statements of operations

9

Indivior PLC

(Amounts in millions, except per share data and percentages)

(Unaudited)

Consolidated balance sheets

10

Indivior PLC

(Amounts in millions, except per share data and percentages)

(Unaudited)

Consolidated statements of cash flows

11

Indivior PLC

(Amounts in millions, except per share data and percentages)

(Unaudited)

Selected revenue and expense information

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Indivior PLC

(Amounts in millions, except per share data and percentages)

(Unaudited)

Reconciliation of GAAP to non-GAAP financial information

We define Non-GAAP effective tax rate as Non-GAAP tax expense divided by Non-GAAP income before taxation.

Non-GAAP diluted earnings/(loss) per share

Management believes that Non-GAAP diluted earnings/(loss) per share, adjusted for the impact of non-recurring items and other adjustments after the appropriate tax amount, may provide meaningful information on underlying trends to shareholders in respect of earnings per ordinary share. Weighted average shares used in computing non-GAAP diluted earnings per share are included in the table above. A reconciliation of GAAP net income to non-GAAP net income is included above.

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