Preclinical Assessment of Steroidal Nanostructured Lipid Carriers Based Gels for Atopic Dermatitis: Optimization and Product Development.

BACKGROUND: Betamethasone Valerate (BV) is a potent topical corticosteroid. Preparation of nanostructured lipid carriers (NLC) involves process parameters optimization and formulations were developed. It is available in several conventional formulations like creams and ointments which have well-known problems of frequent dosing and consequently additional side effects. The aim is to ascertain the probability of NLC as an exclusive carrier for betamethasone valerate topical application with regard to release modulation and improved therapeutic effect. METHOD: Preparation of BVNLC formulations involves rigorous broad range optimization of process parameters viz. selection of lipids, surfactants, formulation technique, stirring time, stirring speed and homogenization cycles. Accordingly, optimized parameters were selected and formulation table was developed. Characterizations of developed NLC comprise particle shape, size, zeta potential, percent drug entrapment, in vitro drug release studies. The optimized NLC formulation was gelled and evaluated for ex vivo permeation studies and preclinical anti-inflammatory testing. RESULTS: The permeation studies revealed that enhancement ratio of BVNLC based gel was 2.59 folds higher as compared to plain BV gel. Release models indicated anomalous (non-fickian) diffusion viz. drug release is controlled by more than one process i.e. superposition of both phenomenon, the diffusion controlled as well as swelling controlled release. Preclinical studies indicated a significant (P < 0.05) extended anti-inflammatory effect and 16.5% inhibition compared to plain gel. CONCLUSION: The outcome of entire characterization advocates that the developed formulation is efficient as once a day dosing in therapy of atopic dermatitis.

Pharmacodynamics and dermatopharmacokinetics of betamethasone 17-valerate: assessment of topical bioavailability.

BACKGROUND: The bioavailability of most topically delivered drugs is difficult to quantify, but is generally believed to be very low. With the exception of the vasoconstrictor assay for corticosteroids, no methodology to quantify the rate and extent of drug delivery to the skin has been validated. Recent research has examined the dermatopharmacokinetic (DPK) technique, which is based on stratum corneum (SC) tape-stripping. OBJECTIVE: To compare the in vivo bioavailability of different topical formulations of betamethasone 17-valerate (BMV) using the vasoconstrictor assay and the DPK method. METHODS: BMV was formulated in different vehicles and the drug concentration was adjusted to either (i) equal thermodynamic activity, or (ii) a range of values up to that corresponding to 80% of maximum thermodynamic activity. Vasoconstriction, an accepted and widely used method to determine bioavailability and bioequivalence of topical steroids, was quantified with a chromameter over 24 h post-removal of the formulation. Drug uptake into the SC was assessed by tape-stripping. RESULTS: BMV at the same thermodynamic activity in different vehicles provoked similar skin blanching responses, while DPK profiles distinguished between the formulations. Further, skin blanching responses and drug uptake into the SC clearly depended upon the absolute BMV concentration applied. However, while the saturable nature of the pharmacodynamic response was clear, the tape-stripping method distinguished unequivocally between the different formulations and different concentrations. CONCLUSIONS: The DPK approach offers a reliable metric with which to quantify transfer of drug from the vehicle to the SC, and may be useful for topical bioavailability and bioequivalence determinations.