Abstract
Prednisolone tablets, enteric coated with neutralised hydroxypropyl methylcellulose phthalate (HPMCP) were compared with Deltacortril tablets (Pfizer) by compendial in vitro testing and a pharmacokinetic study in 12 volunteers. Despite satisfactory compliance for both products with the specifications for enteric products of the European Pharmacopoeia and the United States Pharmacopoeia a significant difference in lag time before prednisolone was detected in plasma was observed between the products and only the Deltracortril tablet was concluded to exhibit true enteric properties
The failure of the neutralised HPMCP coating probably results from incomplete gastric conversion to its acidic form due to the majority of subjects having gastric pH values in excess of those stipulated in the compendial in vitro tests. Alternative in vitro testing procedures are proposed