Amoxicilline

Amoxicilline is a broad-spectrum beta-lactam antibiotic in the penicillin class. It is a semisynthetic derivative of ampicillin and works by inhibiting bacterial cell wall synthesis through blockade of transpeptidase (penicillin-binding proteins), producing time-dependent bactericidal activity.

Amoxicilline has good activity against many Gram-positive cocci such as Streptococcus species and some Gram-negative organisms including Haemophilus influenzae, Escherichia coli, and Proteus mirabilis. It is less effective against beta-lactamase–producing bacteria unless combined with a beta-lactamase inhibitor. For extended coverage, amoxicilline/clavulanate (co-amoxiclav) is used. It is not active against methicillin-resistant Staphylococcus aureus (MRSA) and has limited activity against certain resistant Gram-negatives.

Common clinical uses include otitis media, sinusitis, community-acquired pneumonia, bronchitis, tonsillitis, acute uncomplicated urinary tract infections, dental infections, and prophylaxis for dental procedures in select patients. Dosing and formulation vary by age and site of infection; oral bioavailability is high and peak levels occur within 1–2 hours. Food can affect absorption modestly. The elimination half-life is about 1–1.5 hours in adults, with primary renal excretion requiring dose adjustments in renal impairment.

Adverse effects are usually mild and may include gastrointestinal upset, diarrhea, rash, or hypersensitivity reactions. C. difficile–associated diarrhea and superinfections can occur. Adverse reactions are more common in those with penicillin allergy. Drug interactions may include probenecid (increases levels) and, less commonly, methotrexate or allopurinol (rash risk). Amoxicilline is generally considered safe in pregnancy and lactation, but use should be guided by a clinician.