DrugindexOnline^{2nd edition}

Pronouncation: (uh-MOX-ih-sil-in)
Class: Aminopenicillin, H. pylori agent

Trade Names:
Amoxil
- Tablets, chewable 200 mg (as trihydrate)
- Tablets, chewable 400 mg (as trihydrate)
- Tablets 500 mg (as trihydrate)
- Tablets 875 mg (as trihydrate)
- Capsules 500 mg (as trihydrate)
- Powder for oral suspension 125 mg per 5 mL (as trihydrate) when reconstituted
- Powder for oral suspension 200 mg per 5 mL (as trihydrate) when reconstituted
- Powder for oral suspension 250 mg per 5 mL (as trihydrate) when reconstituted
- Powder for oral suspension 400 mg per 5 mL (as trihydrate) when reconstituted

Trade Names:
Amoxil Pediatric Drops
- Powder for oral suspension 50 mg/mL (as trihydrate) when reconstituted

Trade Names:
Trimox
- Tablets, chewable 125 mg (as trihydrate)
- Tablets, chewable 250 mg (as trihydrate)
- Capsules 250 mg (as trihydrate)
- Capsules 500 mg (as trihydrate)
- Powder for oral suspension 125 mg per 5 mL (as trihydrate) when reconstituted
- Powder for oral suspension 250 mg per 5 mL (as trihydrate) when reconstituted

APO-Amoxi (Canada)
Gen-Amoxicillin (Canada)
Lin-Amox (Canada)
Novamoxin (Canada)
Nu-Amoxi (Canada)

Mechanism of Action

Pharmacology

Inhibits bacterial cell wall mucopeptide synthesis.

Pharmacokinetics

Absorption

Rapidly absorbed. T _max is 1 to 2 h; C _max is 3.5 mcg/mL (250 mg dose), 5 mcg/mL (500 mg dose), and approximately 13.8 mcg/mL (875 mg dose).

Distribution

Diffuses into most body tissues and fluids; penetration in CNS is poor unless meninges are inflamed. Approximately 20% protein bound.

Elimination

T _½ is 61.3 min; approximately 60% excreted in the urine within 6 to 8 h as unchanged drug.

Indications and Usage

Treatment of ear, nose, throat, GU, skin and skin structure, lower respiratory tract, and acute uncomplicated gonorrhea infections caused by susceptible strains of specific organisms.

Contraindications

Hypersensitivity to penicillins, cephalosporins, or imipenem. Not used to treat severe pneumonia, empyema, bacteremia, pericarditis, meningitis, and purulent or septic arthritis during acute stage.

Dosage and Administration

Ear, Nose, Throat, Skin And Skin Structure, GU Tract Infections
Adults and Children Weighing at least 40 kg Mild to moderate infections

PO 500 mg every 12 h or 250 mg every 8 h.

Severe infections

PO 875 mg every 12 h or 500 mg every 8 h.

Children (older than 3 mo of age and weighing less than 40 kg) Mild to moderate infections

PO 25 mg/kg/day in divided doses every 12 h or 20 mg/kg/day in divided doses every 8 h.

Severe infections

PO 45 mg/kg/day in divided doses every 12 h or 40 mg/kg/day in divided doses every 8 h.

Lower Respiratory Tract Infections
Adults and Children Weighing at least 40 kg

PO 875 mg every 12 h or 500 mg every 8 h.

Children (older than 3 mo of age and weighing less than 40 kg)

PO 45 mg/kg/day in divided doses every 12 h or 40 mg/kg/day in divided doses every 8 h.

Acute, Uncomplicated Gonorrhea
Adults

PO 3 g as a single dose.

Prepubertal Children (2 yr of age and older)

PO 50 mg/kg amoxicillin combined with 25 mg/kg probenecid as a single dose.

Storage/Stability

Store Amoxil capsules and 125 and 250 mg unreconstituted powder at or below 20°C (68°F); store 200 and 400 mg unreconstituted powder, chewable tablets, and tablets at or below 25°C (77°F). Store Trimox capsules and unreconstituted powder at or below 20°C (68°F); store chewable tablets at controlled room temperature (15° to 30°C; 59° to 86°F). Dispense in tight containers. Any unused portion of the reconstituted suspension must be discarded after 14 days. Refrigeration is preferable but not required.

Drug Interactions

Contraceptives, oral

May reduce efficacy of oral contraceptives.

Tetracyclines

May impair bactericidal effects of amoxicillin.

Laboratory Test Interactions

May cause false-positive urine glucose test results with Benedict solution, Fehling solution, or Clinitest tablets (enzyme-based tests, eg, Clinistix , Tes-Tape , are recommended); false-positive direct Coombs test result in certain patient groups; false-positive protein reactions with sulfosalicylic acid and boiling test, acetic acid test, biuret reaction and nitric acid test (bromphenol blue test, Multi-Stix , is recommended).

Adverse Reactions

CNS

Dizziness; fatigue; insomnia; reversible hyperactivity.

Dermatologic

Urticaria; maculopapular to exfoliative dermatitis; vesicular eruptions; erythema multiforme; skin rashes.

EENT

Itchy eyes; glossitis; stomatitis; sore or dry mouth or tongue; black “hairy” tongue; abnormal taste sensation; laryngospasm; laryngeal edema.

GI

Gastritis; anorexia; nausea; vomiting; abdominal pain or cramps; epigastric distress; diarrhea or bloody diarrhea; rectal bleeding; flatulence; enterocolitis; pseudomembranous colitis.

Genitourinary

Interstitial nephritis (eg, oliguria, proteinuria, hematuria, hyaline casts, pyuria); nephropathy; vaginitis.

Hematologic

Anemia; hemolytic anemia; thrombocytopenia; thrombocytopenic purpura; eosinophilia; leukopenia; granulocytopenia; neutropenia; bone marrow depression; agranulocytosis; reduced hemoglobin or hematocrit; prolonged bleeding and prothrombin time; increased or decreased lymphocyte count; increased monocytes, basophils, platelets.

Hepatic

Transient hepatitis; cholestatic jaundice.

Metabolic

Elevated serum alkaline phosphatase and hypernatremia; reduced serum potassium, albumin, total proteins, and uric acid.

Miscellaneous

Hyperthermia.

Precautions

Pregnancy

Category B .

Lactation

Excreted in breast milk.

Hypersensitivity

Reactions range from mild to life threatening. Use cautiously in cephalosporin-sensitive patients because of possible cross-allergenicity.

Superinfection

May result in overgrowth of nonsusceptible bacterial or fungal organisms.

Streptococcal infections

Minimum 10 days required for effective treatment.

Overdosage

Symptoms

Hyperexcitability, convulsions.

Patient Information

• Instruct patient to time doses evenly over a 24-h period.
• Inform patient that the medication works best on empty stomach but may be taken with food if there is GI upset.
• Instruct patient to increase fluid intake to 2,000 to 3,000 mL/day unless contraindicated.
• Advise patient to discard oral liquid preparations that are more than 14 days old.
• If therapy is changed because of allergic reaction, explain significance of penicillin allergy and inform patient of potential sensitivity to cephalosporins.
• Instruct patient to report the following symptoms to health care provider: rash, difficulty breathing.