Pharmacokinetics of phenylpropanolamine in humans after a single dose study

Abstract

The pharmacokinetics of phenylpropanolamine have been studied in healthy human volunteers following the oral administration of an aqueous solution of the drug (50 mg/200 ml). Blood and urine samples collected throughout the trial were assayed using HPLC with UV detection. The drug was shown to be rapidly absorbed with a mean tmax of 1.47 ± 0.49 h and a mean elimination half-life of 4.0 ± 0.5 h. Phenylpropanolamine is predominantly excreted via the kidney with a mean renal clearance of 0.646 ± 0.089 liter/kg/h and 90.2 ± 1.7% excreted unchanged in the urine. The data were not well described using conventional one or two body compartment models. However, the incorporation of a discontinuous absorption phase into the models resulted in an improved overall fit with better characterisation of the absorption phase.