Steady state relative bioavailability and pharmacokinetics of oral propranolol in black and white North Americans

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Abstract
The steady state bioavailability and pharmacokinetics of propranolol over two consecutive dosing intervals were investigated in 18 black and 10 white normal volunteers following the administration of 20 mg of a test and reference oral dosage form, respectively, every 6h. There were no differences (p > 0.05) between dosage forms in the mean (n = 28) area under the plasma concentration‐time curve (AUC), maximum plasma concentration (Gmax) or time to Gmax (tmax) for propranolol or its active metabolite, 4‐hydroxypropranolol. However, as a group blacks had lower plasma concentrations of propranolol and 4‐hydroxypropranolol than whites. The mean AUC and Cmax for propranolol during the second dosing interval (AUC‐2 and Cmax‐2, respectively) were significantly (p < 0.05) lower in blacks, but there were no ethnic differences (p > 0.05) in tmax. The mean AUC and Cmax for the 4‐hydroxylated metabolite during both dosing intervals were significantly (p < 0.05) lower in blacks. Mean oral clearances of propranolol, assuming complete absorption, (range: 42.1–54.5 ml min−1 kg−1) were similar (p > 0.05) in each racial group. There were no substantial changes in heart rate or blood pressure in blacks or whites following propranolol administration. These data suggest that for oral propranolol, blacks have different absorption and disposition characteristics than whites.