Should topical antibiotics be used for the treatment of acne vulgaris?

Enhancement of the Skin Permeation of Clindamycin Phosphate by Aerosol OT/1-Butanol Microemulsions

Microemulsions of water/isopropyl palmitate (IPP)/Aerosol OT (AOT)/1-butanol were developed as alternative formulations for topical delivery of clindamycin phosphate. Effect of AOT:1-butanol ratios on microemulsion region existence in the pseudoternary phase diagrams was investigated. The 2:1 AOT:1-butanol provided the largest microemulsion region. Five microemulsions of 1% w/w clindamycin phosphate were prepared and characterized. The permeation through human epidermis of the microemulsions was evaluated and compared with the 70% isopropanol solution using modified Franz diffusion cells. The drug permeation from all microemulsions was found to be significantly greater than that from the solution, indicating the enhancement of the skin permeation by the microemulsions. Within the same microemulsion type, the drug permeation increased with increasing the amount of AOT:1-butanol. The drug permeation from oil-in-water (o/w) microemulsions was relatively higher than that from water-in-oil (w/o) microemulsions. In addition, all microemulsions were stable for at least three months at 30 +/- 1 degrees C.

Clinical evaluation of Double Strength Isotrexin versus Benzamycin in the topical treatment of mild to moderate acne vulgaris

BACKGROUND

Topical retinoid therapy has been shown to be an effective means of treating both the inflammatory and non-inflammatory lesions of acne vulgaris.

AIM

To assess the efficacy and safety of the test product, a gel containing isotretinoin 0.1% w/w and erythromycin 4.0% w/w, with a currently used and effective treatment for mild to moderate acne vulgaris, a gel containing benzoyl peroxide 5.0% w/w and erythromycin 3.0% w/w.

METHODS

This multi-centre, single-blind (investigator blind), parallel group study compared the efficacy and safety of isotretinoin/erythromycin gel (Double Strength Isotrexin) once daily against benzoyl peroxide/erythromycin gel (Benzamycin twice daily in the topical treatment of mild to moderate acne vulgaris. Patients (n = 188) with a history (mean duration 3.3 years) of facial acne vulgaris and with 15-100 inflammatory lesions and/or 15-100 non-inflammatory lesions, but not more than three nodulocystic lesions, were included. At baseline and weeks 2, 4, 8 and 12, the investigator assessed efficacy (total number and severity of inflammatory and non-inflammatory lesions and acne grade) while subjective global change assessments of facial acne from baseline and symptom-specific skin tolerance were assessed by the patient. The investigator recorded an overall global assessment of skin tolerability at week 12. Adverse events were recorded throughout.

RESULTS

The treatments were comparable with regard to their effects on inflammatory and non-inflammatory lesions and acne grade. Few adverse events were considered to be treatment-related. Both the isotretinoin/erythromycin and benzoyl peroxide/erythromycin gels were generally well tolerated. Compliance was better with the isotretinoin/erythromycin gel, which had the advantages of not requiring mixing or storage in a refrigerator, and was applied once rather than twice daily.

CONCLUSIONS

Isotretinoin/erythromycin gel given only once daily showed comparable efficacy with benzoyl peroxide/erythromycin given twice daily in the treatment of mild to moderate acne vulgaris of the face.

Activation of clindamycin phosphate by human skin

AIMS

To investigate the relative antimicrobial activity of clindamycin phosphate (CP) and clindamycin (Cly) and to examine the effect of skin homogenates on the activity of CP.

METHODS AND RESULTS

Minimum inhibitory concentrations (MIC) were determined against dermally relevant organisms and bactericidal activity was studied using time-kill methodology. The effect of skin homogenates on the antimicrobial activity of CP was studied by well-diffusion assay. The MIC of Cly was substantially lower than that of CP in all susceptible organisms. Clindamycin also showed greater bactericidal activity (rate of kill) than CP. Phosphatases in skin homogenates activated CP at pH 4-8 with a maximal activation at pH 4.

CONCLUSION

Phosphatases within the skin have been shown to convert CP to the more potent form Cly.

SIGNIFICANCE AND IMPACT OF THE STUDY

Conversion to Cly is a major determinant of antimicrobial activity in the skin layers following topical application of CP.

Systemic retinoids. What's new?

Despite major advances in the molecular biology and pharmacology of retinoids, no new compound has been developed for systemic use. This article addresses some questions related to the indications of oral retinoids already on the market, e.g. isotretinoin, acitretin, as well as tretinoin, reviews some recently reported undesirable effects, and discusses the recent concepts generated by basic research that may lead to new drugs to be used in pharmacology.

Current options for the topical treatment of acne vulgaris

The etiopathogenesis of acne vulgaris, a common disorder of youth and adolescence, includes four primary processes: hyperkeratinization (plugging) of the pilosebacous follicles, increased testosterone levels, bacterial colonization with Propionibacterium acnes, and inflammation. No single agent has yet been developed that addresses all of these factors. Combination regimens, therefore, which usually include an antibiotic and an agent to reduce follicular plugging, have become the mainstay of treatment. Despite a relative dearth of new treatments for almost a decade, recent research has produced a number of new significant oral and topical agents. Azelaic acid, a naturally occurring dicarboxylic acid analogue, has shown promise, and a group of retinoids that include adapalene, tazarotene, and reformulations of tretinoin represent new and forthcoming agents for topical treatment of acne vulgaris. Some studies indicate that several of these agents are associated with less skin irritation than previous formulations while they retain potent comedolytic activity. Adapalene also possesses significant anti-inflammatory activity.

A comparison of the effectiveness of topical tetracycline, benzoyl-peroxide gel and oral oxytetracycline in the treatment of acne

A proprietary topical tetracycline preparation (Topicycline) was compared with an alcohol-based 5% benzoyl-peroxide gel and with oral oxytetracycline (250 mg twice daily) using a randomized group-comparative double-blind study in 69 patients with mild to moderate acne. Facial acne grades improved significantly in all three treatment groups over the 12-week study period but chest acne grades did not change significantly and only oxytetracycline produced a significant improvement in back grade. All three treatment groups produced a significant reduction in facial inflamed and non-inflamed lesions apart from oxytetracycline which failed to produce a significant reduction in inflamed lesions. However, there were no overall significant differences between the three treatment groups either in improvement of acne grade or in reduction of inflamed and non-inflamed lesions. We conclude that topical tetracycline is as effective as either 5% benzoyl-peroxide gel or 250 mg oxytetracycline twice daily in the treatment of mild to moderate acne.

Topical azelaic acid and the treatment of acne: a clinical and laboratory comparison with oral tetracycline

Topical azelaic acid and oral tetracycline were compared in a 6-month double-blind study for treatment of acne vulgaris in 45 male subjects with clinical acne. Their acne was graded, inflamed or non-inflamed, lesions were counted and the density of their skin microflora was measured. Both treatments were of benefit and produced only a few minor side-effects. Although oral tetracycline was more effective than azelaic acid, the differences were only just significant. The average reduction in numbers of cutaneous micrococcaceae and Propionibacterium sp. with azelaic acid treatment was 224 and 30-fold, respectively. In a separate group of 11 male subjects with physiological acne the effect of azelaic acid on sebum excretion rate was assessed, and little change was detected.

Benzoyl peroxide versus topical erythromycin in the treatment of acne vulgaris

In a double-blind clinical study in ninety-four subjects a 1.5% (w/v) erythromycin lotion was as effective as 5% (w/v) benzoyl peroxide gel in significantly reducing the number of small inflamed lesions and the overall acne severity. However, benzoyl peroxide also significantly reduced the number of non-inflamed lesions whereas erythromycin had no effect on these lesions. This study supports the view that, although topical erythromycin is of value in the treatment of mild or moderate acne vulgaris, long established, safe and effective remedies should not be replaced by topical antibiotics until more comparative studies and investigations on bacterial resistance have been completed.