Amoksillin

Amoksillin, also known as amoxicillin, is a broad‑spectrum beta‑lactam antibiotic in the aminopenicillin subclass. It is a semi‑synthetic derivative of penicillin G and is more acid‑stable, allowing effective oral dosing.

Mechanism of action: It inhibits bacterial cell wall synthesis by binding to penicillin‑binding proteins, disrupting peptidoglycan cross‑linking and leading to bacterial lysis.

Spectrum and limitations: Amoksillin is active against many gram‑positive organisms (eg, Streptococcus pneumoniae, Streptococcus pyogenes, viridans group streptococci) and some gram‑negative pathogens such as Haemophilus influenzae, Moraxella catarrhalis, Escherichia coli, and Proteus mirabilis. It has limited activity against beta‑lactamase–producing bacteria and is ineffective against Pseudomonas aeruginosa or most enterococci. For beta‑lactamase–producing strains, it is often combined with a beta‑lactamase inhibitor (eg, amoxicillin–clavulanate).

Clinical uses: Commonly prescribed for upper respiratory tract infections (otitis media, sinusitis, pharyngitis), community‑acquired pneumonia, uncomplicated urinary tract infections, and certain dental infections. It is also used in Helicobacter pylori eradication regimens in combination with other agents. Dental prophylaxis may involve amoksillin in select patients.

Pharmacokinetics: When taken orally, amoksillin is well absorbed, achieving peak plasma concentrations within 1–2 hours. It distributes widely and is primarily excreted unchanged by the kidneys, with a typical half‑life of about one hour in adults with normal renal function. Dosing is adjusted for renal impairment and infection severity.

Adverse effects and precautions: Common adverse effects include gastrointestinal upset, rash, and allergic reactions. More serious, though rare, hypersensitivity reactions can occur. It can interact with allopurinol and anticoagulants; monitoring for Clostridioides difficile infection is advised. It is contraindicated in individuals with a known penicillin allergy.