No abstract

No abstract

Skin penetration enhancers are used to allow formulation of transdermal delivery systems for drugs that are otherwise insufficiently skin permeable. A full understanding of the mode of action could be beneficial for the design of potent enhancers and for the choice of the enhancer to be used in topical formulation of a special drug. In this study, the structural requirements of penetration enhancers have been investigated using the Quantitative Structure-Activity Relationship (QSAR) technique. Activities of naturally occurring terpenes, pyrrolidinone and Nacetylprolinate derivatives on the skin penetration of 5-fluorouracil, diclofenac sodium, hydrocortisone, estradiol, and benazepril have been considered. The resulting QSARs indicated that for 5-fluorouracil and diclofenac sodium less hydrophobic enhancers were the most active. More precisely, molecular descriptors in the corresponding QSARs indicated the possible involvement of intermolecular electron donor-acceptor interactions. This was in contrast to the skin permeation promotion of hydrocortisone, estradiol, and benazepril by enhancers, where a linear relationship between enhancement activity and n-octanol/water partition coefficients of enhancers was evident. The possible mechanisms of penetration enhancement as suggested by the QSARs will be discussed.3

No abstract

No abstract

-Purpose: Atorvastatin calcium (ATC) is classified as class II (low solubility and high permeability) compound according to the biopharmaceutical classification system. The amorphous form of ATC possesses higher solubility, dissolution rate, and bioavailability than its crystalline form. Coamorphous drug system is a new and emerging method to prepare stable amorphous forms, in this case leading to the improved stability of ATC in dissolution medium. Methods: In this study, coamorphous form of ATC and nicotinamide (ATC-NIC) was prepared from solvent evaporation method and characterized using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR) and powder X-ray diffraction (PXRD). The intrinsic dissolution rate and solubility of ATC-NIC were determined along with plasma concentrations of ATC using HPLC after oral dosing in rats. Results: The crystalline ATC was converted to coamorphous form revealing a molecular interaction between ATC and NIC. The intrinsic dissolution rate, solubility and plasma concentration of coamorphous ATC-NIC are higher than those of crystalline ATC. ATC-NIC coamorphous system showed greater solution stability than those reported in the literature for amorphous ATC. Conclusions: Coamorphous ATC-NIC has improved physicochemical and pharmacokinetic properties as compared to ATC.

No abstract

No abstract