AMOXIL

What it is

Amoxicillin is a semisynthetic antibiotic and is a member of the penicillinase-stable group of penicillins derived from the penicillin nucleus, 6-aminopenicillanic acid.

Approved indications

AMOXIL is intended for use where the patient's condition precludes the administration of the oral form of amoxicillin and is indicated for the treatment of the following infections due to susceptible strains of sensitive organisms. — Septicaemia caused by Haemophilus influenzae, Escherichia coli, Proteus mirabilis, Streptococcus, Streptococcus pneumoniae, Streptococcus faecalis and Salmonella typhi. — Skin and skin structure infections caused by Staphylococcus (non-penicillinase-producing), Streptococcus or Escherichia coli. — Acute and chronic respiratory infections caused by Haemophilus influenzae, Streptococcus, Streptococcus pneumoniae, Staphylococcus (non-penicillinase producing) or Escherichia coli. — Complicated and uncomplicated acute and chronic genitourinary tract infections caused by Escherichia coli, Proteus mirabilis or Streptococcus faecalis. — Gonorrhoea caused by Neisseria gonorrhoeae (nonpenicillinase producing). — Prophylaxis of bacterial endocarditis in individuals at particular risk, such as those with prosthetic heart valves or those who have previously had endocarditis.

Dosing overview

For upper respiratory tract infections, genitourinary tract infections and skin and soft tissue infections, adults receive 250 mg every six to eight hours, whilst children under 20 kg receive 20 mg/kg/day in equally divided doses every six to eight hours. In severe infections or those caused by less susceptible organisms, 500 mg every six to eight hours for adults and 40 mg/kg/day in equally divided doses every six to eight hours for children may be needed. For lower respiratory tract infections, adults receive 500 mg every six to eight hours, whilst children under 20 kg receive 40 mg/kg/day in equally divided doses every six to eight hours. For bacterial septicaemia in more serious infections, adults receive 1 g every six hours by slow intravenous injection or by intravenous infusion, whilst children under 20 kg receive 20 to 40 mg/kg every six hours. In renal impairment the excretion of the antibiotic will be delayed, and depending on the degree of impairment, it may be necessary to reduce the total daily dosage.

Key safety warnings

Serious and occasionally fatal hypersensitivity reactions including anaphylaxis, anaphylactoid and severe cutaneous reactions have been reported in patients receiving beta-lactam antibiotics such as penicillins. Hypersensitivity reactions can also progress to Kounis syndrome, a serious allergic reaction that can result in myocardial infarction. These reactions are more likely to occur in individuals with a history of penicillin hypersensitivity and in atopic individuals, although anaphylaxis has occurred in patients on oral therapy despite being more frequent following parenteral therapy. Drug-induced enterocolitis syndrome has been reported mainly in children receiving amoxicillin and is an allergic reaction with the leading symptom of protracted vomiting (1-4 hours after administration) in the absence of allergic skin or respiratory symptoms. Further symptoms could comprise abdominal pain, diarrhoea, hypotension or leucocytosis with neutrophilia, with severe cases including progression to shock. Antibiotic associated pseudomembranous colitis has been reported with amoxicillin, with a toxin produced by Clostridium difficile appearing to be the primary cause. The severity of the colitis may range from mild to life threatening, and it is important to consider this diagnosis in patients who develop diarrhoea or colitis in association with antibiotic use, which may occur up to several weeks after cessation of antibiotic therapy. Abnormal prolongation of prothrombin time (increased INR) has been reported rarely in patients receiving amoxicillin and oral anticoagulants. Appropriate monitoring should be undertaken when anticoagulants are prescribed concurrently, and adjustments in the dose of oral anticoagulants may be necessary to maintain the desired levels of anticoagulation.

Contraindications

AMOXIL is a penicillin and should not be given to patients with a history of hypersensitivity to beta-lactamase antibiotics, such as penicillins or cephalosporins.

PBS listing

AMOXIL powder for paediatric oral drops 100 mg (as trihydrate) per mL is listed on the PBS with 3 items, unrestricted and authority required restriction types, with an ex-manufacturer price of A$6.37.

Regulatory history

AMOXIL powder for injection (1 g as sodium) was first approved on 21 February 2003. ARTG registrations for AMOXIL include the sugar free syrups (125 mg/5 mL and 250 mg/5 mL) first listed on 14 August 1991, the powder for injection (1 g as sodium) first listed on 14 August 1991, paediatric drops (100 mg/mL) first listed on 21 January 2013, and capsules (250 mg and 500 mg) first listed on 22 June 2016.