A study of drug-excipient interaction and drug product stability using dry (Powder) film coating in comparison with conventional (aqueous) film coating

Abstract

The objective of this work was to study drug-excipient interactions in solid dosage forms when coated with dry powder film-coat compared with conventional aqueous film. Free films of Eudragit RL, (ERL) with or without drugs (Metoprolol Suc-cinate or Diclofenac sodium) were prepared by casting method and characterized by FTIR, NMR, or DSC. Tablets of either drugs were prepared by wet granulation and coated in a fluidized-bed by ERL aqueous dispersion or micronized powder. Dissolution behavior and color change study were carried out for tablet batches on zero time and after 3 months of storage in stability chambers. The results of free films showed a greater possibility of drug polymer interaction in the aqueous dispersion than dry powder films. The results of dissolution rate revealed a greater rate change in aqueous-than in dry-coated tablets. This was confirmed by the Color change study which showed more intense yellowing in aqueous-coated tablets.