A national shortage of metformin modified-release (XR) 500mg tablets is likely to continue for the rest of the year, the TGA has advised.

Supplies of the product are likely to be unavailable for some people with diabetes, forcing the regulator to extend its Serious Shortage Medicine Substitution Notice that was due to expire on 31 July.

“Some brands of metformin may be available during this period, but supply may not be sufficient to meet demand in Australia,” it said in a statement released on 27 July.

The notice allows pharmacists to substitute alternative options of immediate-release metformin 500mg or metformin modified-release 1000 mg tablets, without the prior approval of the doctor.

“Prescribers should be alert to the current shortage of metformin modified-release 500 mg when prescribing to your patients,” the TGA advises.

“If based on your professional and clinical assessment, a change to metformin treatment is deemed appropriate, discuss the changes and counsel your patient on possible adverse effects (e.g. gastrointestinal tolerability).

The TGA has also granted exemptions to allow importation and supply of alternative brands of metformin from other countries such as the UK.