| Popis: |
From introduction: Topical corticosteroids are still the most widely used drugs in the treatment of dermatological conditions. Early corticosteroid dosage forms consisted of simple creams or ointments where more emphasis was placed on the potency of the drug molecule than on the intrinsic delivery potential of the vehicle. More recently, the effect that the composition of the semisolid base has on the extent of drug delivery has been researched to a much greater extent. These advances in the science of dosage form design have necessitated the refinement of precise and accurate methods for testing the drug delivery efficacies of the developed products. Obviously, the best method for the assessment of the effectiveness of corticosteroid formulations is in a therapeutic situation. Clinical trials, however, are fraught with methodological problems that make duplication of a trial impossible. Alternatively, a number of pharmacological models4 exist for this type of assessment, but it is often problematic to obtain correlation with the true dermatological conditions. The human skin blanching assay is one of the most reliable and reproducible of the ill vivo methods available for the assessment of topical corticosteroid formulations. The skin whitening (blanching or vasoconstriction) side-effect that follows corticosteroid application was first utilized in 1962 as a measure of the percutaneous absorption of corticosteroids from topical formulations. Optimization of this initial procedure7.s has produced a reliable and precise bioassay methodology for the assessment of the efficacy of topical corticosteroid formulations. One criticism of this assay has been the subjective nature of the observation procedure. Although these points have repeatedly been addressed in the literature, it has been suggested that it would be beneficial to have some ill vitro penetration data to supplement ill vivo observations, as this would strengthen the assessment of the topical equivalence of similar delivery formulations. With this objective in mind, a comparison of hydrocortisone release from two proprietary cream formulations was compared by in vivo and ill vitro techniques to determine if any correlation could be established between the methodologies. |
