Minocycline in the treatment of acne: latest findings

Minocycline is a semi-synthetic tetracycline antibiotic effective against a wide range of aerobic and anaerobic Gram-positive and Gram-negative bacteria. It is highly active in the pilosebaceous complex, due to its great lipophilicity, and therefore it has been used in the treatment of moderate to severe papulo-pustular acne for a long time. It has an optimal therapeutic range and the percentage of P. acnes resistant strains are still inferior to 5%. Besides the antimicrobial activity, minocycline has an anti-inflammatory action, due to the reduction in neutrophilic chemotaxis, the inhibitory effect on pro-inflammatory cytokines, and the reduction in sebum free fatty acids and bacterial lipases. In 2006 the Food and Drug Administration (FDA) approved a new extended-release formulation of minocycline. This formulation allowed the reduction of some dose-related adverse events, such as those affecting the vestibular system. Besides the dose-related events (nausea, vomiting, and dizziness), minocycline is also known to induce hyperpigmentation, even if less frequently than doxycycline, and is rarely responsible for autoimmune disorders, hypersensitivity reactions, and serum sickness-like reactions. The latest guidelines in the treatment of acne recommend a dose of 50-100 mg, once or twice a daily for the non-modified release minocycline, and 1 mg/kg daily for the new extended-release formulation. This agent is most appropriately used in combination with a topical regimen containing benzoyl peroxide and/or retinoid.