PHARMACOKINETICS AND RELATIVE BIOAVAILABILITY OF FAMCICLOVIA CAPSULE AND FAMCICLOVIA TABLET

A single oral dose 250 mg of domestic famciclovir capsules, domestic famciclovir tablets or imported famciclovir tablets was given to 9 healthy male volunteers at 1 week intervals in a three-way randomized cross-over design, blood samples and urine samples were withdrawn up to 12 h and 24 h, respectively. Famciclovir was deacetylated and oxidized rapidly to form penciclovir after oral administration. Plasma and urine concentrations of penciclovir were determined with HPLC. Two-compartment model with first order absorption was fitted to the concentration-time profiles of these three preparations. The results showed that the mean Tmax of these three preparations were 0.47±0.13 h,0.93±0.40 h and 0.84±0.34 h ; Cmax were 2.34±0.47 mg·L-1,2.20±0.39 mg·L-1 and 2.22±0.66 mg·L-1 ; the plasma half-lives (T1/2β)were about 3 hours; and AUC0-12h were 5.88±0.71 mg·h·L-1,6.24±1.28 mg·h·L-1 and 6.25±1.24 mg·h·L-1,AUC0-∞ were 6.98±0.96 mg·h·L-1,6.82±1.10 mg·h·L-1 and 7.08±1.08 mg·h·L-1, respectively. The accumulating excretion rate of penciclovir in urine in 24 h were 67.1±14.6%,64.6±11.5% and 64.3±10.1% respectively. There was no statistically difference (P0.05) among these three preparations in the above parameters except Tmax. The relative bioavailability of domestic capsule and domestic tablet was 95.7±11.7% and 100.8±15.2% respectively, the result of two one-sided test suggest that these two domestic preparations are bioequivalence with the imported tablet.