Table 3.
Phenytoin metabolic changes comparing both CYP2C9 wild-type and mutant variants
| Study | N | Methods | Results of mutant variants versus wild-type variant | P value |
|---|---|---|---|---|
| Rosemary et al9 | 27 | 300 mg PHT, 4 h after intake | Double ↑ BL-PHT in the presence of mutant alleles | 0.01 |
| Kerb et al89 | 96 | 300 mg PHT, 12 h after intake | 1 mutant allele = ↑ 31% BL-PHT | <0.0001 |
| 2 mutant alleles = ↑ 52% BL-PHT | ||||
| Aynacioglu et al37 | 101 | 300 mg PHT, 12 h after intake | *1/*2 = ↑ 32% BL-PHT | 0.009 |
| *1/*3 = ↑ 35% BL-PHT | 0.001 | |||
| *2/*2 = ↑ 58% BL-PHT | 0.02 | |||
| *3/*3 = ↑ 42% BL-PHT | Not calculated | |||
| Soga et al29 | 28 | Chronic use, 2 h after intake | *1/*3 = ↑ 58% ratio C/D | 0.01 |
| Hung et al8 | 169 | Chronic use, average daily PHT dose of 293.64 ± 75.20 mg/kg/day | *1/*1 CYP2C9 + C19 (mutant) = ↓ 20% Cl | <0.05 |
| *1/*3 CYP2C9 + C19 (mutant) = ↓ 50% Cl | <0.05 | |||
| Ozkaynakci et al90 | 102 | Chronic use, average daily PHT dose of 4.13 ± 1.07 mg/kg/day | Mean BL-PHT: Group CYP2C9 *1/*3 + CYP2C19 *2/*3 = 27.95 ± 1.85 µg/mL (highest) | <0.001 |
| Mean BL-PHT: Group CYP2C9 *1/*1 + CYP2C19 *1/*1 = 7.43 ± 0.73 µg/mL (lowest) |
Abbreviations: N, number of patients; PHT, phenytoin; BL-PHT, blood level of phenytoin; C/D, serum phenytoin concentration/dose of phenytoin; Cl, clearance of phenytoin.