AMOXIL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for AMOXIL (AMOXIL).
Amoxicillin inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), inhibiting transpeptidation and activating autolytic enzymes, leading to bacterial lysis.
| Metabolism | Amoxicillin is primarily metabolized through hydrolysis of the beta-lactam ring to inactive penicilloic acid, accounting for 60-70% of the dose; about 10% is metabolized via hepatic pathways to amoxicilloic acid; renal excretion as unchanged drug is 60-80% via tubular secretion and glomerular filtration. |
| Excretion | Renal: 60-80% unchanged via tubular secretion and glomerular filtration; Biliary/fecal: minor, <5% excreted in bile; dose adjustment in CrCl <30 mL/min. |
| Half-life | Terminal half-life: 1-1.5 hours (normal renal function); prolonged to 7-20 hours in anuria; neonates: 3-4 hours. |
| Protein binding | 17-20%, primarily to albumin. |
| Volume of Distribution | 0.3-0.4 L/kg; indicates distribution into total body water. |
| Bioavailability | Oral: 75-90% (variable with food, decreased absorption); IM: near 100%. |
| Onset of Action | Oral: 30-60 minutes; IM: 1-2 hours; IV: immediate. |
| Duration of Action | 4-6 hours (normal renal); prolonged in renal impairment; dosing interval: 8-12 hours. |
| Action Class | Cell wall active agent -Extended spectrum Penicillin |
| Brand Substitutes | Amoxipen 250mg Capsule, Hipen A 250mg Capsule, Moxipal 250mg Capsule, Mokcan 250mg Capsule, Moxikem 250mg Capsule, Amox C 500mg Injection, Optimox 500mg Injection, Mox 500mg Injection, Vexicin 500mg Injection, Novamox 500mg Injection |
250-500 mg orally every 8 hours or 500-875 mg orally every 12 hours; for severe infections, up to 500 mg every 8 hours or 875 mg every 12 hours.
| Dosage form | FOR SUSPENSION |
| Renal impairment | GFR 10-30 mL/min: 250-500 mg every 12 hours; GFR <10 mL/min: 250-500 mg every 24 hours; hemodialysis: 250-500 mg every 24 hours with an additional dose after dialysis. |
| Liver impairment | No dose adjustment required for mild to moderate hepatic impairment (Child-Pugh class A or B); caution in severe hepatic impairment (Child-Pugh class C) due to limited data. |
| Pediatric use | Neonates ≤28 days: 25-30 mg/kg/day divided every 12 hours; Infants and children >28 days: 20-40 mg/kg/day divided every 8 hours; for otitis media: 50-90 mg/kg/day divided every 8-12 hours. |
| Geriatric use | No specific dose adjustment based solely on age; monitor renal function and adjust dose based on creatinine clearance (CrCl) as per renal adjustment guidelines; maintain adequate hydration. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for AMOXIL (AMOXIL).
| Breastfeeding | Amoxicillin is excreted into breast milk in small amounts, with an M/P ratio of approximately 0.02-0.05. The estimated dose to the infant is less than 1% of the maternal weight-adjusted dose. It is generally considered compatible with breastfeeding. However, potential risks include infant sensitization, diarrhea, and rash. Monitor for these effects. |
| Teratogenic Risk | Penicillins, including amoxicillin, are generally considered low risk in pregnancy. Animal studies have not shown teratogenic effects. In humans, data from large cohort studies and meta-analyses do not indicate an increased risk of major congenital malformations, preterm birth, or low birth weight. Use is acceptable if clinically indicated across all trimesters. |
■ FDA Black Box Warning
None
| Serious Effects |
["Known hypersensitivity to amoxicillin, penicillins, or any component of the formulation","Mononucleosis (high incidence of morbilliform rash)"]
| Precautions | ["Serious hypersensitivity reactions (anaphylaxis) can occur; contraindicated in patients with penicillin allergy","Clostridium difficile-associated diarrhea (CDAD) may occur, ranging from mild diarrhea to fatal colitis","Prolonged use may result in superinfection with resistant organisms","Hepatic dysfunction and cholestatic jaundice (rare)","Skin rashes, including morbilliform rash (common in patients with mononucleosis)","Decreased efficacy when used with bacteriostatic agents (e.g., tetracyclines, chloramphenicol)","Use with caution in patients with renal impairment (CrCl <30 mL/min) due to increased risk of seizures with high doses"] |
| Food/Dietary | No significant food interactions; absorption is not altered by food. Avoid excessive alcohol as it may increase risk of GI side effects and hepatotoxicity (rare). |
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| Fetal Monitoring | No specific fetal monitoring required for amoxicillin use in pregnancy. Standard prenatal care is sufficient. In pregnant women receiving high doses or prolonged therapy, monitor for maternal gastrointestinal effects or allergic reactions. |
| Fertility Effects | There is no evidence that amoxicillin impairs fertility in males or females. Adverse effects on reproduction have not been reported in animal studies. |
| Clinical Pearls | Amoxicillin is a first-line agent for acute otitis media, streptococcal pharyngitis, and uncomplicated community-acquired pneumonia. It has a time-dependent killing mechanism; optimal efficacy requires maintaining serum concentrations above the MIC for >40% of the dosing interval. Dose adjustment is necessary for creatinine clearance <30 mL/min. It is compatible with clavulanate for beta-lactamase coverage. Rash during therapy may indicate non-allergic ampicillin rash (especially with viral infections) or true hypersensitivity; assess carefully. |
| Patient Advice | Take exactly as prescribed; complete the full course even if you feel better. · May be taken with or without food; avoid large meals if GI upset occurs. · Report any rash, especially if accompanied by hives or difficulty breathing. · Do not use leftover antibiotics; discard after completing course. · Use additional contraception if on oral contraceptives (may reduce efficacy). · For suspension: shake well, measure dose with provided device, refrigerate and discard after 14 days. |