Dilantin 100 mg capsules are undergoing a transformation. According to Pfizer, the Food and Drug Administration approved manufacturing changes for Dilantin® (phenytoin sodium). Given this change, which was noted in a September 23, 2007, letter to some pharmacists at the corporate level, we have compiled the following information about:

• Product itself
• Availability for those who use it
• How this change may affect patients in terms of seizure control and side effects

To prepare this article, we talked with media relations at Pfizer, visited various pharmacies in Massachusetts and Rhode Island and spoke with Patty Schafer, RN, MN, the epilepsy.com Resource Specialist, and Barry Gidal, PharmD, at the University of Wisconsin-Madison, and member of the epilepsy.com editorial board.

The new Dilantin

Dilantin® 100 mg extended oral capsules (half orange and half white) are now being manufactured and will replace Dilantin Kapseal® 100 mg. – white with an orange band in the center — which are being discontinued.

• The notice from Pfizer can be viewed at http://professionals.epilepsy.com/pdfs/PFZ_DIL_173_LetterPH_D01.pdf
• The medication sheet at www.epilepsy.com has been updated and can be viewed at http://www.epilepsy.com/pdfs_med/epilepsy_phenytoin.pdf

Jack Cox of Pfizer Media Relations told epilepsy.com “Pfizer did not increase the price with this change.” (However, we are looking into anecdotal reports from pharmacies and patients that are telling us that patient co-pays may be higher.)

Availability of the new Dilantin

Some pharmacies ran out of the original Dilantin and had the new Dilantin on back order. This shortage is expected to be temporary for these pharmacies and the new Dilantin can be drop shipped within a week.

Mike DeAngelis, director of public relations for CVS Pharmacy told epilepsy.com “Our pharmacies will continue to dispense [Dilantin Kapseals] until our inventory is depleted and Pfizer will replenish our supply with the new version. Our customers will receive messaging on their prescription bags explaining the change in appearance.”

This change does not affect the generic versions of Dilantin®, called phenytoin, that are available, nor the 30 mg Dilantin Kapseal.

How this change may affect patients in terms of seizure control and side effects

Patty Shafer said, “We want to encourage users to be proactive. Here are some steps they may want to follow if they are using brand Dilantin:

• Talk to pharmacists before refills are due.
• Make certain the pharmacy has ordered the new formulation.
• Inform the prescribing physician if the pharmacy is not able to get the new Dilantin and in its place the pharmacy gives you a generic version (phenytoin). It is important to be aware that some people have reported changes in seizures and side effects when changing from a brand to generic or from generic to brand. As such, always keep the physician in the loop.

Barry Gidal said, “We don’t have a lot of information from Pfizer regarding why this formulation occurred, or exactly what, if any changes in absorption we can expect with the ‘new’ Dilantin. It is important that patients recognize there is a change in appearance in the medication. In the short term, this may cause some confusion.”

“As for how the ‘old’ Dilantin and the ‘new’ Dilantin compare with respect to absorption; there is again very little information available from Pfizer. The information that is available suggests that the two formulations are bioequivalent according to FDA standards, with perhaps the new formulation actually being slightly better absorbed, at least when taken on an empty stomach.”

He added, “Until we know more specifics, it would seem prudent that patients note when they begin taking the new formulation, and if they experience any change in either side effects or seizure frequency they should contact their physician.”

Edited by Steven C. Schachter, MD