Bioavailability and in-vitro/in-vivo correlation for propranolol hydrochloride extended-release bead products...

The influence of formulation and extrinsic factors has been investigated for the in-vitro release of propranolol hydrochloride from controlled-release beads prepared using aqueous polymeric dispersions, Aquacoat and Surelease. A single-dose three-way crossover bioavailability study of two extended-release experimental formulations (80 mg), Inderal LA (80 mg) and an Inderal immediate-release dosage form (2 x 40 mg) was also conducted and a comparative analysis of pharmacokinetic parameters and the in-vitro release profiles was performed to assess in-vitro/in-vivo correlation. Analysis showed that the in-vitro release data appeared to follow zero-order release kinetics. Intensity of agitation and dissolution method were found to have no significant effect on drug release from beads prepared using either of the coating dispersions studied or Inderal LA. Release of drug from beads coated with Aquacoat was faster in basic media than in acidic media; Surelease-coated beads, however, showed release characteristics that were less sensitive to changes in the pH of the dissolution fluid, and Inderal LA beads showed slower release profiles in acidic medium than in other dissolution media studied. Pharmacokinetic analysis of the data revealed sustained-release absorption characteristics without any evidence of dose-dumping from any of the extended-release dosage forms studied. Regression analysis of the fraction of drug absorbed against the percentage of the drug released in-vitro, at the corresponding times, yielded good in-vitro/in-vivo correlation (level A) for all the extended-release formulations studied. The results showed that there was no dose-dumping from any of extended-release formulations and that the relative bioavailabilities of the experimental formulations were superior to that of the marketed formulation.