Quantitative structure-activity relationship (QSAR) analysis of the cytotoxicities of aminohydroxyguanidine derivatives and their antiviral activities in vitro

Effect of sodium dodecyl sulfate on iontophoresis of hydrocortisone across hairless mouse skin

The purpose of the present work was to study the effect of sodium dodecyl sulfate (SDS), an anionic surfactant, on the iontophoretic transport of a neutral drug hydrocortisone (HC) across hairless mouse skin. The transport studies were conducted using Side-Bi-Side diffusion apparatus and drug concentration in the receptor cell was analyzed using reversed-phase HPLC. A theoretical model was described, tested, and found to agree well with experimental data (R2 = 0.9766). Anodal iontophoresis significantly enhanced the transport of HC compared to cathodal iontophoresis and passive diffusion, suggesting that the transport of the neutral solute occurs via the electro-osmotic flow. The effect of SDS on the transport of HC was highly concentration-dependent and driving mode-dependent. Below the critical micelle concentration (cmc), increasing the concentration of SDS increased both the passive and the iontophoretic fluxes of HC, but the increase was most significant with anodal iontophoresis. Above the cmc, passive transport of HC continued to increase with an increase in the SDS concentration. The transport after anodal iontophoresis, however, reached a plateau and then leveled off. Further increase in SDS concentration decreased flux, suggesting that the transport of micellar-solubilized drug is retarded by anodal iontophoresis, possibly due to electrostatic attraction.

Minimizing systemic absorption of topically administered ophthalmic drugs

Due to absorption several ocularly applied medications give rise to systemic side-effects. The problem of systemic drug absorption should be taken into account in designing ocular drug and dosage forms so that oculospecificity of the medications is optimized. In this review we summarize the current knowledge about the systemic absorption of ocularly applied topical drugs. Special emphasis is directed to the methods that can be used to minimize systemic absorption and increase the oculospecificity of drugs, e.g., reducing volume and increasing viscosity of eyedrops, controlling drug release from depot preparations, prodrug-derivatization, and addition of vasoconstrictive agents.