With exclusivity for the tablet and oral solution formulations of UCB's Keppra (levetiracitam)set to expire in 2008, the company has filed a citizen petition aimed at tightening the requirements for generic versions of antiepileptic drugs.

Exclusivity for Keppra tablets and oral solution expires June 21, 2008, while the compound patent no. 4,943,639 has a July 14, 2008 expiration date.

In an Oct. 3 citizen petition, UCB asks FDA to narrow its "bioequivalence range for generic versions of antiepileptic drugs to require a showing, at the 90% confidence interval, that the lower limit is at least 90% of its reference listed drug."

Additionally, UCB requests that FDA require labeling of all antiepileptic drugs to include a discussion in the warnings section on why physicians and pharmacists should not move patients between antiepileptic drugs if possible.

UCB suggests the warning say, "Physicians and pharmacists should exercise extreme caution when switching patients who are seizure free or whose seizures are well controlled on a given antiepileptic drug. In general, switches in patients who are well controlled and have achieved stability on a given antiepileptic drug should be undertaken only when medically necessary and with full disclosure to the treating physician and the patient."

The petition also calls on FDA to add a section on antiepileptic drugs to the "Orange Book" highlighting the "particular risks associated with substitution of antiepileptic drugs. It should also recommend against switches of antiepileptic drugs in patients who are seizure free or whose seizures are well controlled."

Initially indicated as an adjunctive therapy in the treatment of partial onset seizures in adults and children four years of age and older with epilepsy, FDA recently cleared Keppra for use with other antiepileptic drugs for the treatment of patients with juvenile myoclonic epilepsy (¹ Also see "UCB's Keppra Gains Indication As Adjunctive Therapy For Juvenile Myoclonic Epilepsy" - Pink Sheet, 23 August, 2006.).

FDA also approved an intravenous formulation of Keppra after UCB addressed an "approvable" letter requesting revised product labeling and additional manufacturing information, the firm announced Aug. 2 (² Also see "FDA OKs Intravenous Form Of UCB’s Keppra" - Pink Sheet, 2 August, 2006.).

UCB is developing Keppra follow-on compounds, and a line extension. Once-daily Keppra XR is a near-term answer, while the more potent follow-on agents brivaracetam and selectracetam are the longer-term solutions, the firm said at a Sept. 26 R&D Day in London.

The company will release Keppra XR Phase III results in the fourth quarter of 2007; both follow-on compounds are in Phase II studies.

Other antiepiletics include Pfizer's Neurontin (gabapentin) and the Neurontin follow-on Lyrica (pregabalin), Abbott's Depakote (divalproex), GlaxoSmithKline's Lamictal (lamotrigine) and Johnson & Johnson's Topamax (topiramate).

-Daniel Fowler (d.fowler@elsevier.com)

UCB Attempts To Protect Keppra Franchise

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