The 'Antibiotic Guidelines' do suggest that adults with streptococcal sore throats can be treated with 500 mg of phenoxymethylpenicillin twice a day. This is a convenient regimen and 25 tablets would be enough for a 10 day course. However, this is an example of where the Guidelines can differ from the approved product information (PI) which is the usual guide to the PBAC on how drugs are listed on the Pharmaceutical Benefits Scheme. Until the recent amendment, patients who were prescribed the dose recommended in the PI (250 mg 4 times a day) had to pay for a repeat prescription to complete a 10 day course as the maximum quantity was only 25 tablets.
The new maximum quantity of 50 tablets will meet the needs of doctors who follow the PI as well as those who use the Guidelines. As the pack sizes are unchanged, Dr Shanahan can still write a prescription for 25 tablets.
Ideally, the prescription for a 10 day course should be 20 tablets for 500 mg twice a day or 40 tablets for 250 mg 4 times a day. However, prescribing less than the maximum quantity raises the issue of broken packs for the pharmacist.