[Some factors influencing the bioavailability of zinc in oral pharmaceutical dosage forms]

Absorption and distribution of zinc in 6 dosage forms were determined in 10 subjects by performing a pharmacokinetic study of the serum zinc profile after oral administration of a dose corresponding to 45 mg elemental zinc. The aim of this study was to document the influence on zinc bioavailability of factors such as the chemical form of zinc, the pharmaceutical form, and the division of the administered dose. The pharmacokinetic parameters indicate for gelatin capsules without excipients taken in a non divided dose better performances for zinc gluconate in comparison to zinc sulfate. Concerning the pharmaceutical form, little difference is observed between an aqueous solution and a gelatin capsule for zinc sulfate and a non divided dose; on the contrary, a commercial gelatin capsule containing zinc gluconate with various excipients show better performances than gastro-resistant tablets when zinc intake is 3 times 15 mg. Finally, the division in 3 parts of the dose of zinc sulfate given in gelatin capsules very significantly improves zinc absorption. These results demonstrate the interest of the developed pharmacokinetic method in the assessment of zinc bioavailability in different pharmaceutical dosage forms.