Relative Bioavailability of a Commercial Trifluoperazine Tablet Formulation using a Radioimmunoassay Technique

Abstract

The relative bioavailability of a new conventional tablet formulation (5 mg) of trifluoperazine dihydrochloride was studied in 24 healthy volunteers. Using a sensitive radioimmunoassay technique, plasma trifluoperazine concentrations were measured up until 24h following ingestion of single 5‐mg doses of trifluoperazine. The mean ± SD for the peak concentration (Cmax), time to Cmax, area under the curve from 0 to 24h (AUC240), and terminal elimination half‐life following the administration of the test formulation were 2.15 ± 1.07 ng/mL, 4.10 ± 1.38 h, 21.04 ± 11.92 ng‐h/mL, and 9.5 ± 7 h, respectively. Following the ingestion of the original trifluoperazine tablet formulation (5 mg) these same parameters were estimated to be 1.92 ± 0.88 ng/mL, 4.02 ± 1.10 h, 18.03 ± 10.11 ng‐h/mL, and 9.3 ± 7 h, respectively. Large intersubject variations in Cmax and AUC240 were observed. The relative bioavailability of the test formulation was calculated to be 106.5 ± 25.5%.