Retapamulin

Retapamulin is a pleuromutilin-class antibiotic used as a topical agent for skin infections. It is approved for the treatment of impetigo caused by susceptible strains of Staphylococcus aureus and Streptococcus pyogenes. The medicine is usually marketed as a 1% topical ointment or cream.

Mechanism of action and spectrum: Retapamulin inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit, interfering with the initiation of peptide chain formation. This action renders the drug bacteriostatic against susceptible organisms. Its activity is mainly against Gram-positive cocci, with limited activity against many Gram-negative bacteria; it is not active against most Enterococcus species or resistant Gram-negatives.

Administration and pharmacokinetics: Topical retapamulin is applied directly to the affected skin area and is typically used twice daily for five days. Systemic absorption is minimal, resulting in low systemic exposure and a favorable local safety profile compared with oral agents for impetigo.

Adverse effects and safety: The most common adverse events are local and mild, including application-site redness, itching, burning, or irritation. Serious systemic reactions are uncommon due to limited absorption. It should be used with caution in individuals with known hypersensitivity to retapamulin or other pleuromutilins.

Resistance and history: As with other antibiotics, resistance can emerge through mutations that reduce drug binding to the 50S ribosomal subunit. Retapamulin represents a targeted topical option for uncomplicated impetigo, complementing systemic therapies when appropriate.