The role of oral minocycline and erythromycin in tetracycline therapy-resistant acne—a retrospective study and a review

Abstract

Oral antibiotics are widely used in the treatment of acne, but some patients respond poorly. There are no previous adequate studies comparing the effect of minocycline or other antibiotics in patients who have failed to respond to tetracycline. We investigated 128 patients (64 males and 64 females) who had failed to respond to a general practice prescription of 1 g/day oxytetracycline, supplemented with topical therapy, for a minimum of 6 months. On attending the clinic at Leeds General Infirmary these patients were prescribed 100 mg of minocycline (n = 65) or 1 g of erythromycin (n = 63) daily. Topical therapy was also prescribed. The degree of acne was assessed prior to treatment and at 4 and 8 months of treatment, using the Leeds Technique. Statistical analysis of the data was performed using the non-parametric Mann-Whitney U-test. The results showed an improvement in acne in most patients over 8 months, when therapy was changed from oxytetracycline. The overall acne grades of patients on minocycline improved by 70% compared with 39% improvement in acne for patients receiving erythromycin (P< 0.001). All subjects on minocycline with facial acne got better compared with 77% of patients on erythromycin (P< 0.001). Similarly, 96% of patients with acne on the back improved compared with 75% of patients receiving erythromycin (P = 0.0067). Therefore there is a significant benefit in minocycline therapy compared with erythromycin in oxytetracycline non-responsive acne patients. Minocycline may owe its high efficiency to its high lipophilicity producing higher tissue concentrations. Its non-antimicrobial mechanism of action and its low level of Propionibacterium acnes resistance may also contribute to its efficacy.