How topical antibiotics can be used to treat acne

Topical treatments with either retinoids or antibiotics are recommended for patients with mild to moderate forms of acne. Topical antibiotic treatment agents were extensively used before the 1990s, but this led to the development of bacterial resistance to the antibiotics. Therefore, nowadays doctors are of the opinion that these should be used in combination with topical retinoids or benzoyl peroxide or azelaic acid for greater efficacy as well as to curb bacterial resistance.

Commonly used topical antibiotics are clindamycin and erythromycin.

Mechanism of action

Topical antibiotics work by reducing the population of Propiobacterium acnes (P. acnes) in the hair follicles, particularly on the epidermal surface. This leads to lessening of the skin surface lipids which is produced by the P. acnes lipase activity. Further, topical antibiotics have a mild anti inflammatory effect and antibiotics like clindamycin has the ability to indirectly reduce the formation of comedones as well. Thus, the main mechanism of action of topical antibiotics is the inhibition of inflammation caused by bacteria rather than a direct anti acne effect.

Advantages

They do not cause extreme levels of skin irritation as compared to some topical retinoids.

Disadvantages

Extensive use of antibiotics has led to the emergence of bacterial resistance, i.e. bacteria have learned to survive despite the antibiotics. Once P. acnes become resistant to antibiotics they can pose significant problems for the affected individual such as erythema, peeling, dryness and burning and also relatively low onset of action. Failure of therapy, recurrence or relapse and the colonization of skin with antibiotic resistant Staphycoccus aureus are other adverse effects of bacterial resistence. For this reason topical antibiotics should not be used as a monotherapy and it monotherapy is necessary then it is to be used for a short period lasting only for 3-4 weeks. Treatment should be stopped at once when inflammatory lesions are reduced.

Clindamycin

This is a semi synthetic antibiotic and has been used since the 1970’s for the treatment of acne vulgaris. It is mostly safe and well tolerated. Topical Clindamycin is available as a solution, ointment, gel or pledgetes. There is also a liquid form available with zinc acetate, which helps reduce P.acne counts and helps decrease free fatty acids and surface lipids. There are two topical Clindamycin products namely Dalacin T and Zindalcin.
Erythromycin

Erythromycin reduces the P. acne counts considerably and lessens the formation of microcomedones. Resistent varieties of P. acne can be counteracted by using 4% rather than 2% solutions. Also, adding zinc acetate to the erythromycin formulation has led to enhancement of the treatment’s bactericidal effect as well as sebum suppression.

Reducing bacterial resistance – the importance of combination therapy

Combinations of topical antibiotics with benzoyl peroxide, retinoids and zinc are used in order to maximize bactericidal effect as well as negate the effects of bacterial resistance. These combination also serve to improve absorption of the drugs as well as improved patient compliance.

Combinations include

1) Erythromycin 3% with benzoyl peroxide 5%
2) Erythromycin 4% with tretinoin 0.02% gel
3) Erythromycin 2% with isotretinoin 0.5% gel
4) Erythromycin 1.2% with zinc acetate 0.377% solution
5) Clindamycin 1% and benzoyl peroxide 0.5% gel
6) Clindamycin 1% with tretinoin .02% gel

Efficacy

1) Erythromycin 4% and zinc combination reduced inflammatory lesions by 85% versus 46% reduction using 2% erythromycin alone.
2) Combination of clindamycin 1% with benzoyl peroxide 5% was more effective than either drug used alone in reducing lesions and suppressing P. acnes.
3) Adapalene gel 1% plus clindamycin 1% brought about significant reduction in inflammatory as well as non-inflammatory lesions over a period of 12 weeks.