PHENOXYMETHYLPENICILLIN-AFT

What it is

PHENOXYMETHYLPENICILLIN-AFT contains phenoxymethylpenicillin (as potassium) as the active ingredient. Phenoxymethylpenicillin has a similar antibacterial spectrum to benzyl penicillin, with the advantage of being acid stable and hence better absorbed from the gastrointestinal tract. It produces a bactericidal effect on penicillin sensitive organisms during the stage of active multiplication through inhibition of biosynthesis of cell wall mucopeptides.

Approved indications

— Treatment of mild to moderately severe infections caused by penicillin sensitive staphylococci, pneumococci, gonococci and haemolytic streptococci infections. — Prophylactic use in recurrent streptococcal infections including the prevention of recurrence following rheumatic fever and/or Sydenham's chorea. — Prevention of bacterial endocarditis in patients with rheumatic fever and/or congenital heart disease who are about to undergo dental or upper respiratory surgery or instrumentation.

Dosing overview

For adults, the usual dose is 250 mg to 500 mg every four to six hours, preferably one hour before food. For prevention of recurrence following rheumatic fever, the dose is 250 mg twice a day continuously. For infants and small children, the dose is 15 mg/kg to 50 mg/kg in three to six divided doses, or alternatively: up to 1 year, 60 mg every six hours; 1 to 5 years, 120 mg every six hours; 6 to 12 years, 120 to 270 mg every six hours.

Key safety warnings

Serious and occasionally fatal hypersensitivity (anaphylactoid) reactions have been reported in patients on penicillin therapy. Although anaphylaxis is more frequent following parenteral therapy, it has occurred in patients on oral penicillins. Before initiating therapy, careful inquiry should be made concerning previous hypersensitivity reactions to penicillins, cephalosporins or other allergens. If an allergic reaction occurs, the drug should be discontinued, and serious anaphylactoid reactions require immediate emergency treatment with adrenaline. Antibiotic associated pseudomembranous colitis has been reported with phenoxymethylpenicillin, 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. 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. Severe cutaneous adverse reactions (SCAR), such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS), and acute generalised exanthematous pustulosis (AGEP) have been reported in patients taking beta-lactam antibiotics. When SCAR is suspected, phenoxymethylpenicillin should be discontinued immediately.

Contraindications

Known hypersensitivity to penicillin and/or cephalosporin is a contraindication.

PBS listing

The powder for oral liquid 125 mg (as potassium) per 5 mL is listed on the PBS as 2 items with unrestricted restriction, at an ex-manufacturer price of A$4.53. The powder for oral liquid 250 mg (as potassium) per 5 mL is listed as 2 PBS items with unrestricted restriction, at an ex-manufacturer price of A$5.43.

Regulatory history

PHENOXYMETHYLPENICILLIN-AFT powder for oral liquid 125 mg/5 mL was first listed on the ARTG on 2010-12-21 (ARTG 159753), and the 250 mg/5 mL strength was first listed on the same date (ARTG 159754).