Determination That MYSOLINE (Primidone) Suspension, 250 Milligrams/5 Milliliters, Was Withdrawn From Sale for Reasons of Safety or Effectiveness

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<title>Federal Register, Volume 91 Issue 1 (Friday, January 2, 2026)</title>
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[Federal Register Volume 91, Number 1 (Friday, January 2, 2026)]
[Notices]
[Pages 148-149]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-24196]


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DEPARTMENT OF HEALTH AND HUMAN SERVICES

Food and Drug Administration

[Docket No. FDA-2022-P-3118]


Determination That MYSOLINE (Primidone) Suspension, 250 
Milligrams/5 Milliliters, Was Withdrawn From Sale for Reasons of Safety 
or Effectiveness

AGENCY: Food and Drug Administration, HHS.

ACTION: Notice.

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SUMMARY: The Food and Drug Administration (FDA, Agency, or we) has 
determined that MYSOLINE (primidone) suspension, 250 milligrams (mg)/5 
milliliters (mL), was withdrawn from sale for reasons of safety or 
effectiveness. The Agency will not accept or approve abbreviated new 
drug applications (ANDAs) for primidone suspension, 250 mg/5 mL.

FOR FURTHER INFORMATION CONTACT: Aaron Young, Center for Drug

[[Page 149]]

Evaluation and Research, Food and Drug Administration, 10903 New 
Hampshire Ave., Bldg. 51, Rm. 6254, Silver Spring, MD 20993-0002, 301-
796-8083, <a href="/cdn-cgi/l/email-protection#afceceddc0c181d6c0dac1c8efc9cbce81c7c7dc81c8c0d9"><span class="__cf_email__" data-cfemail="f39292819c9ddd8a9c869d94b3959792dd9b9b80dd949c85">[email&#160;protected]</span></a>.

SUPPLEMENTARY INFORMATION: Section 505(j) of the Federal Food, Drug, 
and Cosmetic Act (FD&C Act) (21 U.S.C. 355(j)) allows the submission of 
an ANDA to market a generic version of a previously approved drug 
product. To obtain approval, the ANDA applicant must show, among other 
things, that the generic drug product: (1) has the same active 
ingredient(s), dosage form, route of administration, strength, 
conditions of use, and (with certain exceptions) labeling as the listed 
drug, which is a version of the drug that was previously approved, and 
(2) is bioequivalent to the listed drug. ANDA applicants do not have to 
repeat the extensive clinical testing otherwise necessary to gain 
approval of a new drug application (NDA).
    Section 505(j)(7) of the FD&C Act requires FDA to publish a list of 
all approved drugs. FDA publishes this list as part of the ``Approved 
Drug Products With Therapeutic Equivalence Evaluations,'' which is 
known generally as the ``Orange Book.'' Under FDA regulations, drugs 
are removed from the list if the Agency withdraws or suspends approval 
of the drug's NDA or ANDA for reasons of safety or effectiveness or if 
FDA determines that the listed drug was withdrawn from sale for reasons 
of safety or effectiveness (21 CFR 314.162).
    A person may petition the Agency to determine, or the Agency may 
determine on its own initiative, whether a listed drug was withdrawn 
from sale for reasons of safety or effectiveness. This determination 
may be made at any time after the drug has been withdrawn from sale, 
but must be made prior to approving an ANDA that refers to the listed 
drug (Sec.  314.161 (21 CFR 314.161)). FDA may not approve an ANDA that 
does not refer to a listed drug.
    MYSOLINE (primidone) suspension, 250 mg/5 mL, is the subject of NDA 
010401, held by FHTA LLC, and initially approved on July 5, 1956. 
MYSOLINE, used alone or concomitantly with other anticonvulsants, is 
indicated in the control of grand mal, psychomotor, and focal epileptic 
seizures. It may control grand mal seizures refractory to other 
anticonvulsant therapy.
    MYSOLINE (primidone) suspension, 250 mg/5 mL, is currently listed 
in the ``Discontinued Drug Product List'' section of the Orange Book.
    Hyman, Phelps & McNamara, P.C. submitted a citizen petition dated 
December 8, 2022 (Docket No. FDA-2022-P-3118), under 21 CFR 10.30, 
requesting that the Agency determine whether MYSOLINE (primidone) 
suspension, 250 mg/5 mL, was withdrawn from sale for reasons of safety 
or effectiveness.
    After considering the citizen petition and reviewing Agency records 
and based on the information we have at this time, FDA has determined 
under Sec.  314.161 that MYSOLINE (primidone) suspension, 250 mg/5 mL, 
was withdrawn for reasons of safety or effectiveness. The petitioner 
has identified no data or other information suggesting that MYSOLINE 
(primidone) suspension, 250 mg/5 mL, was withdrawn for reasons of 
safety or effectiveness. We have carefully reviewed our files for 
records concerning the withdrawal of MYSOLINE (primidone) suspension, 
250 mg/5 mL, from sale. We have also independently evaluated relevant 
literature and data for possible postmarketing adverse events.
    MYSOLINE (primidone) suspension, 250 mg/5 mL, was discontinued in 
2001 after antimicrobial effectiveness testing raised concerns about 
potential microbial contamination, in particular with Pseudomonas 
aeruginosa. As a scientific matter, before MYSOLINE (primidone) 
suspension, 250 mg/5 mL, could be considered for reintroduction to the 
market, a reformulation would be required including establishment of 
preservative content acceptance criteria and correlation with passing 
antimicrobial effectiveness testing results. The NDA holder for 
MYSOLINE (primidone) suspension, 250 mg/5 mL, would have to demonstrate 
the safety and effectiveness of the reformulated product. At this time, 
no new formulation has been approved for MYSOLINE (primidone) 
suspension, 250 mg/5 mL.
    Accordingly, under Sec.  314.162 the Agency will remove MYSOLINE 
(primidone) suspension, 250 mg/5 mL, from the list of drug products 
published in the Orange Book. FDA will not accept or approve ANDAs that 
refer to this drug product.

Lowell M. Zeta,
Acting Deputy Commissioner for Policy, Legislation, and International 
Affairs.
[FR Doc. 2025-24196 Filed 12-31-25; 8:45 am]
BILLING CODE 4164-01-P


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Determination That MYSOLINE (Primidone) Suspension, 250 Milligrams/5 Milliliters, Was Withdrawn From Sale for Reasons of Safety or Effectiveness

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