Amoxicillin: Indication, Dosage, Side Effect, Precaution

Generic Medicine Info Patient Medicine Information

This information is not country-specific. Please refer to the Myanmar prescribing information.

Generic Medicine Info

Indications and Dosage

Oral
Dental abscesses

Adult: 3 g, repeated once after 8 hours. Consideration must be given to local treatment guidelines.

Oral
Uncomplicated gonorrhoea

Adult: In patients with susceptible non-penicillinase producing N. gonorrhoeae strains: 3 g as a single dose in combination with probenecid. Consideration must be given to local treatment guidelines.

Oral
Pharyngitis, Tonsillitis

Adult: In acute streptococcal cases: 500 mg 8 hourly or 750-1,000 mg 12 hourly. For severe infections: 750-1,000 mg 8 hourly for 10 days. Consideration must be given to local treatment guidelines.
Child: <40 kg: 40-90 mg/kg daily in divided doses; ≥40 kg: Same as adult dose.

Oral
Acute bacterial sinusitis, Acute otitis media, Cystitis, Ear, nose and/or throat infections, Genitourinary infections, Pyelonephritis, Skin and soft tissue infections

Adult: Individualise dosing based on expected susceptible pathogens, severity and site of infection, age, weight and renal function of the patient. 250-500 mg 8 hourly or 500-1,000 mg 12 hourly. For severe infections: 750-1,000 mg 8 hourly. Consideration must be given to local treatment guidelines.
Child: >3 months <40 kg: 20-90 mg/kg daily in divided doses; ≥40 kg: Same as adult dose.

Oral
Paratyphoid fever, Typhoid fever

Adult: 500-2,000 mg 8 hourly. Consideration must be given to local treatment guidelines.
Child: <40 kg: 100 mg/kg daily in 3 divided doses; ≥40 kg: Same as adult dose.

Oral
Prophylaxis of endocarditis

Adult: 2 g as single dose 30-60 minutes prior to procedure. Consideration must be given to local treatment guidelines.
Child: <40 kg: 50 mg/kg as single dose 30-60 minutes prior to procedure; ≥40 kg: Same as adult dose.

Oral
Uncomplicated acute urinary tract infections

Adult: 3 g, repeated once after 10-12 hours. Consideration must be given to local treatment guidelines.

Oral
Community-acquired pneumonia

Adult: 500-1,000 mg 8 hourly. Consideration must be given to local treatment guidelines.
Child: >3 months <40 kg: 20-90 mg/kg daily in divided doses; ≥40 kg: Same as adult dose.

Oral
Eradication of H. pylori associated with peptic ulcer disease

Adult: In combination with PPI (e.g. omeprazole, lansoprazole) and another antibiotic (e.g. clarithromycin, metronidazole): 750-1,000 mg bid for 7-14 days depending on therapy regimen. Consideration must be given to local treatment guidelines.

Oral
Acute exacerbations of chronic bronchitis, Asymptomatic bacteriuria in pregnancy

Adult: 250-500 mg 8 hourly or 750-1,000 mg 12 hourly. For severe infections: 750-1,000 mg 8 hourly. Consideration must be given to local treatment guidelines.

Oral
Lyme disease

Adult: In early stages: 500-1,000 mg 8 hourly for 14 days (range: 10-21 days). Max: 4,000 mg daily in divided doses. In late stages (systemic involvement): 500-2,000 mg 8 hourly for 10-30 days. Max: 6,000 mg daily in divided doses. Consideration must be given to local treatment guidelines.
Child: <40 kg: In early stages: 25-50 mg/kg daily in 3 divided doses for 10-21 days. In late stages (systemic involvement): 100 mg/kg daily in 3 divided doses for 10-30 days. ≥40 kg: Same as adult dose.

Parenteral
Bacterial meningitis

Adult: In combination with another antibiotic if needed: 1-2 g 4-6 hourly via slow IV inj over 3-4 minutes or IV infusion over 20-60 minutes. Doses may be also be given via IM inj if IV route is impossible or less appropriate for the patient. Max: 12 g daily (IV); 4 g daily (IM); 1 g (single IM dose). Consideration must be given to local treatment guidelines.

Parenteral
Endocarditis

Adult: Treatment in combination with another antibiotic if needed: 1-2 g 4-6 hourly via slow IV inj over 3-4 minutes or IV infusion over 20-60 minutes. Doses may be also be given via IM inj if IV route is impossible or less appropriate for the patient. Max: 12 g daily (IV); 4 g daily (IM); 1 g (single IM dose). Prophylaxis in patients at highest risk of infective endocarditis: 2 g as single IV dose 30-60 minutes prior to procedure. Consideration must be given to local treatment guidelines.
Child: Treatment: ≥40 kg: Same as adult dose. Prophylaxis in patients at highest risk of infective endocarditis: <40 kg: 50 mg/kg as single IV dose 30-60 minutes prior to procedure; ≥40 kg: Same as adult dose.

Parenteral
Acute exacerbations of chronic bronchitis, Community-acquired pneumonia, Cystitis, Ear, nose and/or throat infections, Pyelonephritis, Skin and soft tissue infections

Adult: Individualise dosing based on expected susceptible pathogens, severity and site of infection, age, weight and renal function of the patient. 500 mg 8 hourly via slow IV or IM inj. Severe infections: May increase to 1,000 mg 6 hourly via slow IV inj over 3-4 minutes or by IV infusion over 20-60 minutes. Alternatively, 750-2,000 mg 8 hourly or 2,000 mg 12 hourly via slow IV inj or IV infusion. Doses may be also be given via IM inj if IV route is impossible or less appropriate for the patient. Max: 12 g daily (IV); 4 g daily (IM); 1 g (single IM dose). Consideration must be given to local treatment guidelines.
Child: >3 months <40 kg: 20-200 mg/kg daily given in 2-4 equally divided doses of up to 25 mg/kg or infusions of up to 50 mg/kg; ≥40 kg: Same as adult dose.

Renal Impairment

Oral:
GFR <10 mL/min and/or patients on peritoneal dialysis: Adults and children ≥40 kg: Max: 500 mg daily; Children <40 kg: 15 mg/kg daily (max: 500 mg daily). GFR 10-30 mL/min: Adults and children ≥40 kg: Max: 500 mg bid; Children <40 kg: 15 mg/kg bid (max: 500 mg bid). In patients receiving haemodialysis: Adults and children ≥40 kg: 500 mg 24 hourly, and give an additional 500 mg dose prior to and after dialysis; Children <40 kg: 15 mg/kg once daily (max: 500 mg daily), and give an additional 15 mg/kg dose prior to and after dialysis.

Parenteral:
GFR <10 mL/min and patients on peritoneal dialysis: Adults and children ≥40 kg: 1,000 mg as IV loading dose then 500 mg daily via IV, or 500 mg daily as single IM dose; Children <40 kg: 25 mg/kg daily as single IV dose, or 15 mg/kg daily as single IM dose. GFR 10-30 mL/min: Adults and children ≥40 kg: 1,000 mg as IV loading dose followed by 500-1,000 mg bid via IV, or 500 mg 12 hourly via IM; Children <40 kg: 25 mg/kg bid via IV, or 15 mg/kg 12 hourly via IM. In patients receiving haemodialysis: Adults and children ≥40 kg: 1,000 mg at the end of dialysis then 500 mg 24 hourly via IV, or 500 mg during and at the end of dialysis then 24 hourly via IM; Children <40 kg: 25 mg/kg as IV loading dose, followed by 25 mg/kg daily, and additional 12.5 mg/kg dose at the end of dialysis via IV; alternatively, 15 mg/kg during and at the end of dialysis, then 15 mg/kg 24 hourly via IM.

Administration

May be taken with or without food. May be taken w/ meals for better absorption & to reduce GI discomfort.

Reconstitution

Powder for solution for inj or infusion: IV inj: Reconstitute vial labelled as 500 mg with 10 mL of sterile water for inj to make a final volume of 10.4 mL. IV infusion: Further dilute prepared solution to 50 mL of suitable IV fluid (e.g. sterile water for inj, NaCl). IM: Reconstitute vial labelled as 500 mg with 2.5 mL of sterile water for inj to make a final volume of 2.9 mL. Shake the vial vigorously; administer within 30 minutes of reconstitution. Refer to detailed product guideline for further compatible infusion fluids and their stability.

Incompatibility

Powder for solution for inj or infusion: Incompatible with blood products, other proteinaceous fluids (e.g. protein hydrolysates), IV lipid emulsions, infusions containing dextran or bicarbonate; aminoglycosides (in same syringe or IV fluid container).

Contraindications

Hypersensitivity or history of severe allergic reactions (e.g. anaphylaxis, Stevens-Johnson syndrome) to amoxicillin or other β-lactams (e.g. penicillins, cephalosporins, carbapenems, monobactams). Infectious mononucleosis (suspected or confirmed).

Special Precautions

Patient with reduced urine output, history of seizures, treated epilepsy or meningeal disorders; lymphatic leukaemia. Atopic individuals. Renal and hepatic impairment. Children. Pregnancy and lactation.

Adverse Reactions

Significant: Convulsion (high doses), Jarisch-Herxheimer reaction (in treatment of Lyme disease). Rarely, crystalluria (high parenteral doses); prolonged prothrombin time.
Blood and lymphatic system disorders: Rarely, thrombocytopenia, leucopenia.
Gastrointestinal disorders: Nausea, diarrhoea, vomiting; tooth discolouration (brown, yellow, grey) particularly in children.
Investigations: Elevated liver enzymes, changes in blood counts (prolonged therapy).
Nervous system disorders: Headache, dizziness, agitation.
Psychiatric disorders: Reversible hyperactivity, anxiety, insomnia, confusion, behavioural changes.
Reproductive system and breast disorders: Vulvovaginal infection.
Skin and subcutaneous tissue disorders: Rash, urticaria, pruritus.
Potentially Fatal: Hypersensitivity reactions including anaphylaxis, anaphylactoid and severe cutaneous adverse reactions (e.g. Stevens-Johnson syndrome, toxic epidermal necrolysis, acute generalised exanthematous pustulosis, drug reaction with eosinophilia and systemic symptoms); C. difficile-associated diarrhoea or pseudomembranous colitis. Rarely, cholestatic hepatitis.

Pregnancy Category (US FDA)

PO: B

Monitoring Parameters

Perform culture and susceptibility tests; consult local institutional recommendations before treatment initiation due to antibiotic resistance risks. Monitor renal, hepatic, and haematologic (e.g. CBC with differential) functions periodically with prolonged therapy; electrolyte balance. Assess patient for infection throughout therapy; signs or symptoms of anaphylaxis (during initial dose), opportunistic infections, and antibiotic-associated diarrhoea.

Overdosage

Symptoms: Nausea, vomiting, diarrhoea, disturbance of fluid and electrolyte balances; crystalluria leading to renal failure (in some cases) and convulsions. Management: Symptomatic and supportive treatment. Monitor water or electrolyte balance. Maintain adequate fluid intake and diuresis. May consider haemodialysis for removal from the circulation.

Drug Interactions

Decreased renal tubular secretion resulting in increased and prolonged serum concentration with probenecid. Increased risk of allergic reactions (e.g. rashes) with allopurinol. Tetracyclines, chloramphenicol, macrolides, and sulfonamides may interfere with the bactericidal effect of amoxicillin. May prolong prothrombin time or increase INR when used with oral anticoagulants (e.g. warfarin, acenocoumarol). May reduce the excretion and increase the toxicity of methotrexate. May reduce the efficacy of oral contraceptives (e.g. estrogen/progesterone combination).

Lab Interference

May interfere with the result in assay for estriol in pregnant women. May result in false-positive reactions with urinary glucose tests using Benedict’s solution or Fehling’s solution.

Action

Description: Amoxicillin is a semisynthetic aminopenicillin that inhibits the final transpeptidation step of peptidoglycan synthesis in bacterial cell walls by binding to 1 or more of the penicillin-binding proteins (PBPs), thereby inhibiting cell wall biosynthesis and causing eventual bacterial lysis.
Pharmacokinetics:
Absorption: Rapidly and well absorbed from the gastrointestinal tract. Bioavailability: Approx 70% (oral). Time to peak plasma concentration: 1-2 hours (oral).
Distribution: Readily distributed in gall bladder, abdominal tissue, lungs, liver, prostate, middle ear effusions, maxillary sinus secretions, skin, fat, bone, muscle tissues, peritoneal and synovial fluids, bile, pus; poor penetration into the brain and CSF (except when meninges are inflamed). Crosses the placenta and enters breast milk (small amounts). Volume of distribution: Approx 0.3-0.4 L/kg. Plasma protein binding: Approx 20%.
Metabolism: Metabolised via hydrolysis (small amount) to inactive penicilloic acid.
Excretion: Via urine (60% as unchanged drug). Elimination half-life: Approx 1 hour.

Chemical Structure

Storage

Store between 20-25°C. Protect from moisture and light. Reconstituted oral susp: Store below 25°C or between 2-8°C. Do not freeze.

MIMS Class

Penicillins

ATC Classification

J01CA04 - amoxicillin ; Belongs to the class of penicillins with extended spectrum. Used in the systemic treatment of infections.

References

Amoxicillin 250 mg/5 mL Oral Suspension (Bristol Laboratories Ltd). MHRA. https://products.mhra.gov.uk/. Accessed 11/06/2020.

Amoxicillin 500 mg Hard Capsules (Kensington Pharma Ltd.). MHRA. https://products.mhra.gov.uk/. Accessed 11/06/2020.

Amoxicillin 500 mg Powder for Solution for Injection or Infusion (Ibigen Srl). MHRA. https://products.mhra.gov.uk/. Accessed 11/06/2020.

Amoxicillin Capsule (West-Ward Pharmaceuticals Corp). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 11/06/2020.

Amoxicillin Tablet, Film-Coated (Aurobindo Pharma Limited). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 11/06/2020.

Amoxil Oral Preparations (GlaxoSmithKline Philippines Inc). MIMS Philippines. http://www.mims.com/philippines. Accessed 10/09/2020.

Anon. Amoxicillin. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 11/06/2020.

Apo-Amoxi Capsules and Oral Suspension (Apotex Inc.). MIMS Singapore. http://www.mims.com/singapore. Accessed 10/09/2020.

Buckingham R (ed). Amoxicillin. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 11/06/2020.

Cilamox Capsule, Suspension (Aspen Pharma Pty Ltd). MIMS Hong Kong. http://www.mims.com/hongkong. Accessed 01/07/2020.

Douglas Pharmaceuticals Ltd. Ibiamox Powder for Injection data sheet 11 April 2018. Medsafe. http://www.medsafe.govt.nz/. Accessed 01/07/2020.

Joint Formulary Committee. Amoxicillin. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 11/06/2020.

Synamox Capsules (Idaman Pharma Manufacturing Sdn Bhd). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my/. Accessed 11/06/2020.

Synamox Oral Suspension (Idaman Pharma Manufacturing Sdn Bhd). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my/. Accessed 11/06/2020.

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