Amoxicillin: Uses, Dosage, Side Effects, and More
1. Drug Name
Generic Name: Amoxicillin
Brand Name(s):
- Pakistan: Amoxil, Biomox
- India: Mox, Amoxil
- United States: Amoxil, Moxatag
- United Kingdom: Amoxil, Trimox
2. Pharmacological Class
Class: Antibiotic
Subclass: Penicillin
3. Mechanism of Action
Amoxicillin works by inhibiting the synthesis of bacterial cell walls. It binds to specific penicillin-binding proteins inside the bacterial cell wall, leading to cell lysis and death.
4. Indications
Primary Indications:
- Treatment of bacterial infections such as sinusitis, pneumonia, ear infections, bronchitis, urinary tract infections, and skin infections.
Off-label Uses:
- Prevention of bacterial endocarditis in at-risk individuals undergoing dental procedures.
5. Dosage and Administration
Standard Dosage:
- Adults (mild to moderate infections): 500 mg every 12 hours or 250 mg every 8 hours.
- Adults (severe infections): 875 mg every 12 hours or 500 mg every 8 hours.
Route of Administration: Oral (tablets, capsules, chewable tablets, and suspension).
Special Populations:
- Pediatric: Dosage is weight-based, typically 20-40 mg/kg/day in divided doses.
- Geriatric: No specific dose adjustment required, but caution advised in renal impairment.
6. Pharmacokinetics
Absorption: Amoxicillin is well absorbed from the gastrointestinal tract.
Distribution: It is widely distributed in body tissues and fluids.
Metabolism: Amoxicillin is metabolized in the liver.
Excretion: It is primarily excreted unchanged in the urine.
Half-life: Approximately 1-1.5 hours.
7. Contraindications
Amoxicillin is contraindicated in patients with a history of allergic reactions to penicillins or cephalosporins.
8. Warnings and Precautions
Use with caution in patients with renal impairment or a history of gastrointestinal disease, particularly colitis.
Prolonged use may result in fungal or bacterial superinfection, including C. difficile-associated diarrhea.
9. Side Effects
Common Side Effects: Nausea, vomiting, diarrhea, and rash.
Serious Side Effects: Anaphylaxis, Stevens-Johnson syndrome, and Clostridium difficile-associated diarrhea.
10. Drug Interactions
Major Interactions: Methotrexate (increased risk of toxicity).
Moderate Interactions: Oral contraceptives (reduced efficacy).
Minor Interactions: Probenecid (increased amoxicillin levels).
11. Pregnancy and Lactation
Pregnancy Category: Category B - No evidence of risk in humans.
Breastfeeding Considerations: Amoxicillin is excreted in breast milk in small amounts. Use with caution.
12. Patient Counseling Information
Key Points for Patients:
- Take amoxicillin exactly as prescribed, even if you feel better before completing the course.
- Report any signs of allergic reaction, such as rash, itching, or swelling, to your doctor immediately.
Administration Tips:
- Take with or without food. If stomach upset occurs, take with food.
- Shake the suspension well before each use and measure the dose with the provided measuring device.