ETROCIN

Indications

• Respiratory tract infections
• Skin and soft tissue infections
• Pelvic inflammatory disease
• Chlamydia infections
• Legionnaires' disease
• Whooping cough
• Urethritis caused by Mycoplasma genitalium

Dosage

Children: Refer to the BNF for Children for appropriate pediatric dosing recommendations.

Adults: Refer to specific dosing guidelines in the BNF or consult a healthcare provider for tailored dosing information.

Mechanism of action

Erythromycin binds to the 50S ribosomal subunit of susceptible bacteria, inhibiting RNA-dependent protein synthesis. This binding prevents the translocation of peptides, effectively halting bacterial growth and replication.

Pharmacodynamics

The pharmacodynamic profile of erythromycin exhibits bacteriostatic activity at lower concentrations and bactericidal activity at higher concentrations. Its effectiveness is influenced by the susceptibility of the target organism and the concentration of the drug at the site of infection. Erythromycin is active against a variety of organisms, including Streptococcus pneumoniae, Staphylococcus aureus (some strains), and Mycoplasma species.

Pharmacokinetics

Erythromycin is absorbed well from the gastrointestinal tract, although the presence of food can reduce its absorption. It is distributed widely throughout the body, with good penetration into tissues and fluids, including bile and bronchial secretions. Erythromycin is metabolized primarily in the liver via cytochrome P450 enzymes and is excreted mainly in bile, with a smaller percentage appearing in urine. The half-life of erythromycin is approximately 1.5 to 2 hours.

Contra-indications

• Hypersensitivity to erythromycin or any of its components
• History of cholestatic jaundice or hepatic dysfunction associated with erythromycin

Adverse effects

• Gastrointestinal disturbances such as nausea, vomiting, abdominal pain, and diarrhea
• Hepatotoxicity, including jaundice and elevated liver enzymes
• Allergic reactions, including rash and anaphylaxis
• QT prolongation leading to potential arrhythmias

Interactions

• May interact with CYP3A4 substrates, leading to increased serum levels of certain medications such as statins, benzodiazepines, and calcium channel blockers
• Concomitant use with other QT-prolonging drugs may increase the risk of arrhythmias
• May enhance the effects of warfarin, necessitating closer monitoring of INR

Precautions

• Use with caution in patients with hepatic impairment
• Monitor for signs of Clostridium difficile-associated diarrhea
• Consider alternative therapy in patients with a history of arrhythmias or electrolyte imbalances

Pregnancy

Erythromycin is generally considered safe for use during pregnancy, but should only be used when clearly needed.

Breast-feeding

Erythromycin is excreted in breast milk, but is generally considered safe for use during breastfeeding if prescribed.

Storage

Store at room temperature, away from moisture and heat. Protect from light.

Formulations

• Oral tablets
• Oral suspension
• Topical ointment
• Intravenous solution