Intra- and intersubject variation of erythromycin absorption from single-unit and multiple-unit enteric-coated products.

Based on the in vitro dissolution test for erythromycin capsules introduced in USP XX, Suppl. 3, there are no reasons to expect any difference in bioavailability after administration of two enteric-coated products, tablets and pellets in hard capsules. The present results in vivo are contradictory and, following duplicate administrations of the two preparations to 12 volunteers after a standardized breakfast, it is apparent that the multiple-unit, pellets, produce a better reproducibility in absorption both within and between subjects than the single-unit tablets. All subjects attained measurable levels of erythromycin on all occasions after administration of pellets, while levels were below the detectable limit on six out of the 24 occasions tested after administration of tablets. The better reproducibility of serum levels after pellets than after tablets was also shown in a descriptive way and is given as a low median discrepancy value of 23.5 per cent (moderate) compared to 73.2 per cent (large).