PACE Case: Phenytoin

A 59-year old female participant presented with a broken hip due to a fall. She has cerebral palsy with developmental delay, depression, seizure disorder, and a history of falls and alcoholism. Her medications at the time of the fall were multivitamins, folic acid, phenytoin 200mg at bedtime, and fluoxetine. The PACE physician contacted the CK clinical pharmacist because, within the six months since enrollment, her phenytoin dose had been changed twice, and had been a challenge to manage.

The PACE clinician consulted with the CK clinical pharmacist on the effect of alcohol on phenytoin level. The pharmacist informed the PACE clinician that alcohol’s effect on phenytoin level depends on frequency of alcohol consumption. Acute, heavy alcohol consumption may increase phenytoin levels (reduced clearance of the drug). On the other hand, chronic, heavy alcohol consumption may decrease phenytoin level (increased clearance of the drug). Phenytoin levels may also be expected to be lower during alcohol withdrawal.

Upon further discussion, the pharmacist and clinician agreed that levetiracetam (Keppra) would be a better suited anticonvulsant, given the participant’s history of alcohol abuse. Keppra is mostly metabolized by the kidneys (and, to a lesser extent, via enzyme hydrolysis), thus offering a better likelihood of achieving a sustained therapeutic level.
The pharmacist recommended gradual discontinuation of phenytoin, as drug clearance would be hard to predict. Further, she recommended drawing phenytoin levels at baseline and over time to gauge rate of decrease. Pharmacist also recommended the appropriate dose of Keppra, based on participant’s renal function (CrCl 50-80 mL/min: 500-1000 mg every 12 hours).

While recovering from her fall injury, the participant was admitted to a nursing home. She was discharged after two months and returned to her usual activities and care with the PACE program. Participant is reported as stable on current dose of Keppra.

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