Professional Information

Amoxicillin

Pronunciation: (a-MOX-i-SIL-in)
Class: Aminopenicillin, Helicobacter pylori agent

Trade Names:
Amoxicillin
- Powder for oral suspension 125 mg per 5 mL (as trihydrate)

Trade Names:
Amoxicillin
- Powder for oral suspension 200 mg per 5 mL (as trihydrate)

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 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:
DisperMox
- Tablets for suspension 200 mg
- Tablets for suspension 400 mg
- Tablets for suspension 600 mg

Trade Names:
Moxatag
- Tablets, extended-release 775 mg

Trade Names:
Trimox
- Powder for oral suspension 125 mg per 5 mL (as trihydrate) when reconstituted

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

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).

Extended-release

C _max is 6.6 mcg/mL; T _max is 3.1 h.

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.

In combination with clarithromycin and/or lansoprazole for the eradication of H. pylori .

Moxatag

Treatment of tonsillitis and/or pharyngitis secondary to Streptococcus pyogenes .

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

Acute, Uncomplicated Gonorrhea
Adults

PO 3 g as a single dose.

Prepubertal Children (2 yr of age and older)

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

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.

H. Pylori Eradication
Adults Triple Therapy

PO Amoxicillin 1 g, clarithromycin 500 mg, and lansoprazole 30 mg all given twice daily (every 12 h) for 14 days.

Dual therapy

PO Amoxicillin 1 g and lansoprazole 30 mg each given 3 times daily (every 12 h) for 14 days.

Impaired Renal Function
Adults

PO Glomerular filtration rate (GFR) of 10 to 30 mL/min: Administer 500 or 250 mg every 12 h, depending on the severity of the infection.

GFR less than 10 mL/min: Administer 500 or 250 mg every 24 h, depending on the severity of the infection.

Hemodialysis patients: Administer 500 or 250 mg every 24 h, depending on the severity of the infection, plus an additional dose during and at the end of dialysis.

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.

Tonsillitis, Pharyngitis
Adults and Children 12 yr and older

PO Extended-release tablet: 775 mg once daily, within 1 h of finishing a meal, for 10 days.

Storage/Stability

Store DisperMox tablets for oral suspension, capsules, tablets, chewable tablets, powder for oral suspension at 68° to 77°F. Store Moxatag extended-release tablets at 59° to 86°F. Store 500 mg and 875 mg tablets at 68° to 77°F. Dispense in tightly closed, light-resistant container. Store 250 and 500 mg capsules at 68° to 77°F. Store 250 and 500 mg capsules, 125 mg per 5 mL, 200 mg per 5 mL, 250 mg per 5 mL, and 400 mg per 5 mL unreconstituted powder at 68° to 77°F.

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

Drug Interactions

Chloramphenicol, macrolide antibiotics (eg, erythromycin), sulfonamides

May impair bactericidal effects of amoxicillin.

Contraceptives, oral

May reduce efficacy of oral contraceptives.

Methotrexate

Methotrexate plasma levels may be elevated, increasing the risk of toxicity.

Probenecid

Renal tubular secretion of amoxicillin may be reduced, resulting in increased and prolonged amoxicillin blood levels.

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

Agitation; anxiety; behavioral changes; confusion; convulsions; dizziness; headache; hyperactivity; insomnia.

Dermatologic

Acute generalized exanthematous pustulosis; erythema multiforme; erythematous maculopapular rashes; exfoliative dermatitis; mucocutaneous candidiasis; Stevens-Johnson syndrome; toxic epidermal necrolysis; urticaria.

GI

Diarrhea (2%); nausea (1%); black, hairy tongue; hemorrhagic pseudomembranous colitis; tooth discoloration; vomiting.

Genitourinary

Crystalluria; vulvovaginal mycotic infection.

Hematologic-Lymphatic

Agranulocytosis; anemia; eosinophilia; hemolytic anemia; leukopenia; thrombocytopenia; thrombocytopenic purpura.

Hepatic

Acute cytolytic hepatitis; cholestatic jaundice; hepatic cholestasis; increased ALT and AST.

Hypersensitivity

Anaphylaxis; hypersensitivity vasculitis.

Miscellaneous

Serum sickness–like reactions.

Precautions

Monitor

Periodically assess renal, hepatic, and hematopoietic function during prolonged therapy. Patients diagnosed with gonorrhea should have a serologic test for syphilis at the time of treatment and a follow-up serologic test after 3 months.

Pregnancy

Category B .

Lactation

Excreted in breast milk.

Children

Moxatag

Safety and efficacy not established in children younger 12 yr of age.

Elderly

Differences in response between elderly patients (65 yr of age and older) and younger patients have not been identified.

Hypersensitivity

Serious and occasionally fatal hypersensitivity (eg, anaphylactic) reactions may occur. Use with caution in cephalosporin-sensitive patients because of possible cross-allergenicity.

Renal Function

Moxatag

Dosage reduction may be necessary. Administration is not recommended in patients with severe renal function impairment (CrCl less than 30 mL/min) or patients on hemodialysis.

Superinfection

May result in overgrowth of nonsusceptible bacterial or fungal organisms.

Phenylketonurics

Amoxil 200 and 400 mg chewable tablets contain phenylalanine.

Pseudomembranous colitis

Consider possibility in patients with diarrhea.

Streptococcal infections

Minimum 10 days required for effective treatment.

Overdosage

Symptoms

Convulsions, crystalluria, hyperexcitability, interstitial nephritis.

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.
Take Moxatag with food.
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: difficulty breathing, rash.