[Penetration of radioactive hydrocortisone in human skin from various ointment bases. II. In vivo-experiments (author's transl)]

Absolute concentrations in the horny layer, epidermis, and dermis of therapeutical doses of topically applied hydrocortisone to human skin (in vivo) are reported. Using vaseline as vehicle 2-10(-4) molar concentrations are found in the epidermis and 3-10(-5) molar concentrations in the dermis. Further, three vehicles revealed minor concentrations. Comparison of the results with similar in vitro-investigations, reported earlier, allow to judge the resorption rate by the intact capillary system. Uptake of hydrocortisone by the vessels is observed. With high rates of penetration vasoconstriction seems to limit the resorption, while this is not the case with low rates, for instance with polyethyleneglycol as vehicle. Thus a differing drug liberation from the vehicle causes qualitatively different permeation kinetics. The elimination by urine, however, was practically the same. It is concluded that different vehicles may cause different therapeutic concentrations of the drug in the skin, but equal systemic side effects.

Urea creams in the treatment of dry skin and hand dermatitis

Two randomized, double-blind comparison studies were conducted to evaluate the efforts of 2 emollient dry skin creams containing urea in the management of dry skin in atopic patients. Cream with 10% urea was shown to be effective in the management of dry skin and hand dermatitis. The cream with a pH of 6 caused less burning.

Release of corticoids from oleaginous ointment bases containing drug in suspension

Simplified methods for studying the release of drugs suspended in oleaginous ointment bases were developed. These procedures were used in studying the release rates of two corticoids, fluocinonide and flucloronide, from white petrolatum and petrolatum containing various adjuvants. A practical method for measuring drug solubilities was developed and used in determining solubilities of these corticoids in ointment bases. When using physical data obtained from model ointments, the release rates of drugs from modified ointment bases were predicted. Comparisons of the observed and predicted rates from ointments containing hydrophobic adjuvants indicated the usefulness of the physical model approach in predicting the release rates. For ointments containing emulsifying agents, the simple model used did not provide useful predictions.

Absolute concentrations of dithranol and triacetyl-dithranol in the skin layers after local treatment: in vivo investigations with four different types of pharmaceutical vehicles

The pharmacokinetics of dithranol (anthralin) and its triacetate were investigated by employing a method which determines the quantity of the drug that penetrated into single layers of the human skin in vivo. For this purpose, tritium-labeled dithranol or triacetyl-dithranol was incorporated into four different ointments. The ointments were applied to the skin and biopsies were taken after 10, 30, 100, and 1000 min. The horny layer was removed before biopsy by Scotch tape stripping. The biopsies were sliced horizontally and the tritium determined in each sample. Dithranol as well as its triacetate penetrated best from more hydropholic ointments (Vaseline and aqueous wool-wax-alcohol ointment). From hydrophilic ointments (polyethylene glycol ointment and aqueous hydrophilic cream), only poor penetration was observed. Dithranol penetrated in far greater amounts than its triacetate, and the two compounds revealed fundamentally different penetration kinetics in epidermis and dermis. The data indicate that the triacetate was not split into its parent compound, dithranol, in substantial quantity, as the data obtained show the criteria of two independent substances.

Laboratory and clinical evaluation of a new topical anesthetic

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