[Effect of dermatocorticoids on the activity of hepatic tryptophane pyrrolase in the guinea pig (author's transl)]. / Wirkung von Dermatocorticoiden auf die Aktivität der hepatischen Tryptophanpyrrolase beim Meerschweinchen.

The enzyme activity of tryptophane pyrrolase in guinea pig liver can be measurably increased--as in other mammalian species--by systemic administration of corticoids, but this effect is short-lived and achieved only with high s.c. doses of, e.g., prednisolone (Ultracorten-H-hydrosoluble). In contradistinction and rather surprisingly the enzyme activity is variably but markedly reduced by high-dosed and protracted epicutaneous application (10 times within 2 weeks) of the well-known dermatocorticoids: hydrocortisone, fluocinolone acetonide, and clobetasol propionate. This reaction must be explained by the capacity of these corticoids to inhibit, after their percutaneous absorption, the functional axis pituitary--adrenal cortex--liver, the stimulatory role of which is mandatory for the endogenous basic activity of hepatic tryptophane pyrrolase.

Epidermal antihyperplastic effects of contact antiphlogistics.

The inhibitory effects of six contact antiphlogistics and two dermatocorticoids on hexadecane-induced hyperplasia of the guinea-pig skin were tested and compared. On the basis of the results obtained, the substances can be ranked in the following order of potency (percent inhibition of surface epithelial proliferation): acetylsalicylic acid (7.9%), phenylbutazone (12.5%), bufexamac (16.4%), bendazac (16.6%), oxyphenbutazone (19.5%), indomethacin (20.0%), hydrocortisone (20.6%) and fluocinolone acetonide (32.0%).

Effect of topical salicylic acid on animal epidermopoiesis.

In contrast to its antihyperplastic effect on pathological proliferation of the epidermis, salicylic acid promotes epidermopoiesis in the normal guinea pig skin. After the application of 1% w/w salicylic acid in acetone-ethanol for 4 weeks, the thickness of the surface epithelium was increased by 40% and that of the deep epithelium by 19%. The mitotic index rose by 17%.

New experimental model for the primary evaluation of topical contra-inflammatory agents.

Assays of steroidal and non-steroidal drugs in an experimental model of dermatitis induced in the ear of the rabbit by the application of a solution of croton oil revealed clearly differentiable inhibitory effects on the rise in skin temperature, the oedema and the increase in tissue mass due to the inflammatory process. The results obtained in this test system fairly accurately reflect the relative therapeutic potencies of known dermatocorticoids and, in conjunction with those found by other methods, afford a more exact characterization of the activity profiles of non-steroidal contra-inflammatory agents.

[Pattern of epithelium formation in human and guinea-pig skin (author's transl)]. / Formationsmuster des Hautepithels bei Mensch und Meerschweinchen

Comparative histometry of human and guinea-pig epidermis revealed that in the latter development of the (subcorneal) superficial epithelium is significantly less, and that of the (mostly follicular) deep epithelium is markedly more pronounced than in man.

Dermatopharmacology of salicylic acid. III. Topical contra-inflammatory effect of salicylic acid and other drugs in animal experiments.

The acute contra-inflammatory effects of salicylic acid, three standard dermatocorticoids and four contact antiphlogistics have been investigated by means of a UV dermatitis inhibition test in the guinea pig. The substances tested had a distinct inhibitory effect on the development of erythema and can be ranked in the following ascending order of activity (percent of maximum possible score): bufexamac = 36%, salicylic acid = 37%, hydrocortisone = 44%, acetylsalicylic acid = 48%, flumethasone pivalate = 51%, fluocinolone acetonide = 51%, phenylbutazone = 56%, and indomethacin = 58%.

Dermatopharmacology of salicylic acid. II. Epidermal antihyperplastic effect of salicylic acid in animals.

The influence of salicylic acid on pathological epithelial proliferation has been evaluated by means of the peidermal hyperplasia inhibition test in the guinea pig. 3% w/w salicylic acid dissolved in ethanol reduced surface epithelial hyperplasia by 15%, i.e. exhibited activity comparable to that of hydrocortisone 0.1% w/w. 1% w/w salicylic acid dissolved in a dimethylacetamide-acetone-ethanol mixture exerted an even greater degree of antihyperplastic activity on the surface epithelium (-18%) and also a marked inhibitory effect on deep epithelial proliferation (-10%).