Exhibit 99.8

Consent of Jefferies LLC

The Board of Directors
Indivior Pharmaceuticals, Inc.

10710 Midlothian Turnpike, Suite 125

North Chesterfield, Virginia 23235

The Board of Directors:

We hereby consent to the inclusion of our opinion letter, dated July 31, 2026, to the Board of Directors of Indivior Pharmaceuticals, Inc. (“Indivior”) as Annex E to, and reference to such opinion letter under the headings “SUMMARY – Opinions of Indivior’s Financial Advisors – Opinion of Jefferies LLC” and “THE MERGER – Opinions of Indivior’s Financial Advisors – Opinion of Jefferies LLC” in, the joint proxy statement/prospectus relating to the proposed transaction involving Indivior and Supernus Pharmaceuticals, Inc. (“Supernus”), which joint proxy statement/prospectus forms a part of the Registration Statement on Form S-4 of Indivior (the “Registration Statement”). By giving such consent, we do not thereby admit that we are experts with respect to any part of such Registration Statement within the meaning of the term “expert” as used in, or that we come within the category of persons whose consent is required under, the Securities Act of 1933, as amended, or the rules and regulations of the Securities and Exchange Commission promulgated thereunder.

August 28, 2026