15th March 2024

Macrolides

These drugs bind to the 50S ribosomal subunit interfering with protein synthesis. They have broad spectrum activity against gram-negative, gram-positive and mycobacteria. They are particularly useful in those with penicillin-resistant staphylococci and in pregnancy. Clindamycin, a lincosamide, is closely related to macrolides but has a narrower spectrum covering gram-positive and anaerobic bacteria.

Macrolides, except azithromycin, inhibit the CYP3A4 isoenzyme, potentiating the effects of certain drugs, including carbamazepine, ciclosporin and simvastatin. They are also known to cause gastrointestinal symptoms such as discomfort, nausea and vomiting. Other adverse effects include the unmasking or worsening of myasthenia gravis and QT prolongation. Erythromycin can cause cholestatic drug-induced liver injury, which tends to be self-limiting after cessation of the drug.