Unfortunately, estimation of the extent of drug displacement from albumin is very complex when these medications are administered concomitantly. This study showed that none of the residents had to have phenytoin concentrations adjusted based on creatinine clearance. Most of these nursing home residents did not have extensive renal disease. Subacute care is playing an increasingly important role in our facilities, and these types of residents will be encountered more frequently. The elderly residents studied here generally required smaller doses of antiepileptic medications.
Adequate monitoring is essential to promote efficacy and avoid potential toxicity.
Trough serum phenytoin concentrations should be assessed 10 to 14 days after initiation of therapy, and if a dosage change has been made, every 6 to 12, months during long-term therapy, or when seizure activity is observed or toxicity is suspected. If previous albumin was normal and there is no reason to suspect a decrease, no other levels are needed. Albumin levels should be drawn along with phenytoin levels every 6 to 12 months in residents with a history of hypoalbuminemia. Pamela Walker-Renard, Pharm. American hospital formulary service.