Effect of film coating on cephalexin gastric-floating tablets

Aim: To study the influence of the film coating on the release profile and floating lag time of cephaelxin gastric-floating tablets. Methods: The floating tablets with various hardness from 4 kg to 12 kg was coated with Opadry®, Opadry® II, Opadry® AMB, Eudragit RL 30D, RS 30D or RL 30D/RS 30D (1:1) with increases in tablets weight ranging from 1% to 3%. Results: The tablets, coated with each of three kinds of Opadry, with various increases in tablets weight or hardnesses, showed the release of cephalexin similar to the uncoated tablets. But the coated tablets had floating lag time 15 minutes later than that of the uncoated tablets. If cephalexin tablets with hardness of 6-9 kg were coated with Eudragit RL 30D/RS 30D (1:1) with coating increases in tablet weight ranging 1%-2%, there was no evidence that the coating retarded the release, and the tablets floated within 15 minutes. Conclution: The application of the selected polymers forming the coating film of suitable tensile strength and high water and low CO₂ permeabilities allows the initiation of the rapid floating process rapidly and leads to no changes to the release profiles of the tablets.