A probe has been launched into the stability of two drugs received from a supplier for the management of tuberculosis (TB), Health Minister Manto Tshabalala-Msimang said on Monday.

"The department received information suggesting that the ingredients in two fixed-drug combination products supplied by Pharmascript were not at the level stated in the label after storage," she said in a statement.

The products are ANTIB-4, a four-in-one combination of PZA, ethambutol, isonazid and rifampicin, and EBSAR, a two-in-one combination of isoniazid and rifampicin.

While an assay of stock on the shelves for six months showed nothing amiss, a three month accelerated stability test on the same batch showed lower levels of the ingredients than was claimed.

"Further tests are being conducted on the stability of these products," said Tshabalala-Msimang.

The reasons for the findings were also under investigation, including possible interaction between the various ingredients, the effect of packaging and whether the formulation was sub-optimal.

Follow up tests had to be done to confirm the findings before action on the products' registration status could be taken by the Medicine Control Council.

Precautionary measures to be taken

The Health Minister said all TB fixed-drug-combinations on tender were also being tested.

The results of the investigations were expected by the end of October.

"As a precautionary measure, the Department of Health has decided to withdraw all ANTIB-4 and EBSAR products that are four months and older from circulation."

She also voiced concern at the packaging mix-up involving the Adcock-Ingram antiretroviral drugs, AZT batch number 1J expiring in January 2009, and Nevirapine batch number 1Z expiring in November 2008.

"Since these batches were manufactured in 2007, there is a likelihood that a number of patients have been already affected.

"We are appealing to all the patients who are in possession of these batches to consult their health professionals for possible side effects.

"We are monitoring the recall which will continue until all the cartons are returned."

Sapa