Premium
Double‐Blind Randomized Study Comparing Brand‐Name and Generic Phenytoin Monotherapy
Author(s) -
Mikati Mohamad,
Bassett Nancy,
Schachter Steven
Publication year - 1992
Publication title -
epilepsia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.687
H-Index - 191
eISSN - 1528-1167
pISSN - 0013-9580
DOI - 10.1111/j.1528-1157.1992.tb02328.x
Subject(s) - crossover study , phenytoin , potency , brand names , capsule , medicine , randomized controlled trial , double blind , generic drug , pharmacology , anesthesia , chemistry , epilepsy , drug , advertising , biochemistry , botany , biology , business , alternative medicine , pathology , psychiatry , in vitro , placebo
Summary: Ten patients with well‐controlled seizures receiving chronic phenytoin (PHT) monotherapy for seizure prophylaxis completed a randomized double‐blind crossover study comparing brand‐name and generic PHT. Each patient received the same dose of each preparation for 3 months during which trough PHT concentrations and adverse effects were monitored. The average predose steady‐state total PHT concentration was 11.9 ± 4.9 μg/ ml during brand‐name therapy and 14.2 ± 8.2 pg/ml during generic therapy. The average predose steady‐state free PHT concentrations were 0.93 ± 0.47 μg/ml (brand name) and 1.14 ± 0.64 μg/ml (generic), respectively (p < 0.005). The potency (capsule content) values for the lots used in the study were 99.2% for the brand‐name and 104.6% for generic. Because of the nonlinear MichaelisMenten kinetics of PHT, a 5.4% difference in potency could account for the observed differences in plasma concentrations. When compared with brand‐name PHT therapy, the generic drug was associated with an increase in serum concentration. This increase was consistent with the reported difference in capsule content between the generic and brand‐name lots used in this study.