The clinical use of diphenylhydantoin (Dilantin) blood levels

Serum diphenyl hydantoin (DPH) levels are now a useful clinical tool in managing epileptic patients. There is also a role for the use of DPH blood levels in other clinical situations that require DPH such as cardiac arrhythmias, certain pain syndromes, etc. Because the amount taken by mouth may give variable blood levels, and it is the blood level that determines the therapeutic effectiveness, the use of DPH blood levels in following patients is extremely important. When any patient is put on long term DPH therapy, they should have a blood level performed about 1 mth after starting therapy. At this point, the patient's blood level will have stabilized and one can determine if the dosage is adequate (making sure that the patient is taking his drug regularly). DPH levels should then be done whenever there is any indication of poor control, toxicity, or a question of poor compliance. The use of DPH blood levels enables better control of these patients and encourages them to take their drug regularly.