Pharmacological properties : תכונות פרמקולוגיות

Pharmacodynamic Properties

5.1   Pharmacodynamic properties
Pharmacotherapeutic group: Anti-acne preparations for topical use, anti-infectives, erythromycin in combination with tretinoin. ATC code: D10AF52

Erythromycin:
Erythromycin possesses a strong antibacterial effect with respect to Propionibacterium acnes, a skin germ to which a significant role in the pathogenesis of acne is attributed.
Clinical trials have shown that after topical application erythromycin penetrates into the sebaceous gland ducts, where its bacteriostatic effect unfolds. The anti-microbial activity corresponds to that of penicillin, comprising gram-positive and some gram-negative germs.
Erythromycin is reversibly bound to the 50 S subunit of the ribosomes of the bacteria, thus inducing inhibition of their protein biosynthesis.


Restriction of the enzymatic activity of the bacterium inhibits lipolysis of the skin surface lipids, reducing the concentration of free fatty acids.
Erythromycin results in clinical improvement to the acne efflorescences; the local antibiotic therapy is comparable in terms of its efficacy to the systemic administration of the antibiotic.
Furthermore, erythromycin also has a direct anti-inflammatory effect. The alcoholic base of Aknemycin Plus supports the antibacterial effect of erythromycin, while at the same time removing the skin sebum.

Tretinoin:
Tretinoin (vitamin A acid) is a deep-acting keratolytic agent. Tretinoin belongs to the group of retinoids and has a stimulating effect on the proliferation of the cornified cells of the skin. It binds to a cellular protein (CRABP) and in this way infiltrates the cell nucleus. The adhesiveness of the cornified cells formed under the influence of tretinoin is reduced and the development of cornified cell “plugs” in the acroinfundibulum of the follicle channel prevented.
Tretinoin leads to comedolysis and a reduction in the size of the sebaceous glands. Open comedones are loosened and ejected, while closed comedones are transformed more rapidly into open ones and eliminated. During application with tretinoin the local effect is initially accompanied by irritation and an increase in the blood supply to the skin. Comedones that are not clinically visible are transformed into inflammatory ones and ejected, while persistent papules and nodes are removed more quickly.
The skin irritation caused by tretinoin is largely attenuated by the combination with erythromycin.
Aknemycin Plus is well tolerated by the skin; seborrhoeic skin conditions are normalised. In the hypersensitivity test according to Magnusson-Kligman there were no indications of hypersensitivity caused by Aknemycin Plus.

Pharmacokinetic Properties

5.2    Pharmacokinetic properties

After the topical application of erythromycin the substance cannot be detected in the serum; absorption therefore only occurs in quantities that are not detectable, if at all.
Details on the absorption of tretinoin fluctuate between 0.5 % and a maximum of 24 %. The substance is rapidly degraded to polar metabolites and excreted via the intestines and kidneys; there is no storage in the liver. Systemic pharmacodynamic effects as a consequence of local treatment are not to be expected, particularly in view of the concentration used in the preparation.