Plasma level studies on different brands of sodium diphenylhydantoin (DPH) and primidone.

Comparative plasma level studies on different brands of sodium diphenylhydantoin (DPH) and primidone are described. Steady state plasma levels of both drugs were measured in epileptic patients who were chronically maintained on this medication. Simultaneous measurements of phenobarbital, primidone and diphenylhydantoin were carried out by gas chromatography. Drug product equivalence and clinical significance of plasma levels of DPH and primidone are discussed.