Amoxycillin is a broad-spectrum, bactericidal, beta-lactam antibiotic belonging to the aminopenicillin class. It is a semisynthetic derivative of ampicillin with enhanced oral bioavailability. It acts by inhibiting bacterial cell wall synthesis, leading to osmotic lysis and cell death. It is effective against a wide range of Gram-positive and some Gram-negative bacteria but is susceptible to degradation by beta-lactamases. It is a first-line agent for many common infections in the Indian primary care setting.
Adult: Mild to Moderate Infections: 250-500 mg orally every 8 hours. Severe Infections/Respiratory Infections: 500-875 mg every 12 hours or 500 mg every 8 hours.
Note: May be taken with or without food. Taking with food may reduce gastrointestinal upset. Capsules/Tablets should be swallowed whole with a full glass of water. The oral suspension must be shaken well before each use. Complete the entire prescribed course even if symptoms improve.
Amoxycillin binds to specific penicillin-binding proteins (PBPs) located on the inner membrane of the bacterial cell wall. This binding inhibits the final transpeptidation step of peptidoglycan synthesis in the bacterial cell wall, a critical structural component. The inhibition leads to the activation of autolytic enzymes (autolysins) in the cell wall, resulting in lysis and death of the bacterium.
Pregnancy: Pregnancy Category A (Australian categorization). Considered compatible for use during pregnancy. Extensive clinical experience has not shown an increased risk of malformations. Use only if clearly needed.
Driving: Amoxycillin is not known to impair the ability to drive or operate machinery. However, patients experiencing dizziness or other CNS effects should exercise caution.
| Probenecid | Decreases renal tubular secretion of amoxycillin, increasing and prolonging its blood levels. | Moderate |
| Methotrexate | Amoxycillin may reduce renal clearance of methotrexate, increasing risk of methotrexate toxicity. | Major |
| Allopurinol | Concomitant use increases the incidence of non-allergic skin rash. | Moderate |
| Oral Contraceptives | May reduce efficacy of oral contraceptives due to altered enterohepatic circulation; advise use of a non-hormonal backup method. | Moderate |
| Warfarin and other Anticoagulants | May potentiate anticoagulant effect, increasing risk of bleeding; monitor INR closely. | Major |
| Other Bacteriostatic Antibiotics (e.g., Tetracyclines, Chloramphenicol) | May theoretically antagonize the bactericidal effect of amoxycillin. | Moderate |
Same composition (Amoxycillin (250mg)), different brands: