The TGA has approved an alternative treatment for acute angina after it was revealed that formulation problems with the existing PBS listed drug could be putting patient safety at risk.

The regulatory body reported last year that a new formulation of glyceryl trinitrate (GTN) tablets was taking longer than expected to dissolve.

Other reports also suggested that the new circular 600 mcg tablets, which can be broken in half for patients who are prescribed a 300 mcg dose, were difficult to split.

Drug sponsor, Arrow Pharmaceuticals, who sells the tablets in Australia under the brand names Anginine and Lycinate is working to reformulate the product.

However the TGA has said the longer than usual dissolving times associated with the new formulation could prevent some patients from receiving ‘adequate or timely’ therapy, prompting its search for an alternative product.

It has now approved an application to supply Nitrostat tablets into Australia granting the drug PBS listing earlier this month.

But the medical authority has warned that availability of the drug, which has been sourced from the US and is being supplied by Pfizer Australia, may not meet demand.

To avoid a potential medicine shortage, it said the current formulation of Anginine and Lycinate tablets will not be recalled.

Cardiologists have been advised to tell any patients who are still prescribed the drug that drinking a mouthful of water before putting a GTN tablet under their tongue may help it to dissolve. Patients should seek urgent medical attention if their chest pain continues, the TGA warned.

The newly approved Nitrostat tablets contain the same active ingredient as Anginine and Lycinate tablets and are also meant for sublingual use.

However, Nitrostat tablets are not scored and cannot be broken in half.

“Therefore, Nitrostat tablets are also available as 300 mcg tablets, which give an equivalent dose to half an Anginine or Lycinate tablet,” the TGA advised.

Additionally, a total of three Nitrostat tablets can be taken over 15 minutes compared with a total of two Anginine or Lycinate tablets over 10 minutes.

The TGA also recommends that patients can use a spray-based formulation of GTN, marketed as Nitrolingual Pump Spray, which delivers a dose of 400 mcg instead of the 600 mcg or 300 mcg tablet dose.

“This should be considered, along with the patient’s ability to use the spray correctly, in any decision to switch to that product,” the TGA cautioned.