Australians who use the drug Valium are being urged to return all 5 milligram packets of tablets in a national recall, after the drug's manufacturer found evidence of tampering.

The substitute drugs: BTC Paracetamol Codeine tablets: used for short-term treatment of acute strong pain

used for short-term treatment of acute strong pain Rosuvastatin 10mg tablets: used to lower cholesterol levels

used to lower cholesterol levels Apotex-Pantoprazole 40mg tablets: used to treat and help heal duodenal and gastric ulcers The TGA said these drugs were some of the suspected substitute drugs used, but there may be more. The drug information is from NPS MedicineWise.

Manufacturer Roche recalled all packs of 50 Valium 5 milligram tablets after packets were found to contain different drugs.

About 30,000 packs are distributed across the nation every month.

Roche Products managing director Svend Peterson urged customers to return their Valium to pharmacists.

"I am not sure how many patients would be affected, but it's important that the packets are returned and that patients seek medical advice," he said.

"We are uncertain as to when this issue started, however we are taking every measure possible to ensure patient safety."

Mr Peterson said Roche was unsure when the tampering began but it was "very recent and of a small scale".

"We don't know if it involves one or more workers but we believe it's very limited and contained to one unit."

The tampering occurred at a distribution centre, Mr Peterson said, and the company informed the TGA as soon as they found out.

"There should be no concern for individual Valium tablets themselves — it's purely about the tampering of these packets of 50 and the use of alternative medicines."

TGA issues recall

The Therapeutic Goods Administration (TGA) issued a recall of batches of Valium products last Friday, saying in a statement it is looking into potential medicine tampering.

In a statement the TGA said Valium 5mg tablets contain diazepam, which is used to treat anxiety disorders, alcohol withdrawal symptoms and muscle spasms.

"It has been identified that blister pack sheets containing other medicines have been substituted into some packs of Valium 5 mg tablets," the statement said.

"These medicines may include (but may not be limited to) BTC Paracetamol Codeine tablets, BTC Rosuvastatin 10 mg tablets and Apotex-Pantoprazole 40 mg tablets.

"If a patient has an affected pack, there is a risk that they will not have adequate supply of their medicine and could take the incorrect medicine, which could have serious health consequences."

New South Wales police said they were investigating the theft of a quantity of Valium over a period of time at a business in Rydalmere in north-west Sydney.

A spokesman for the Consumers Health Forum of Australia, Mark Metherell, said the recall was surprisingly low-profile.

"It is disturbing," Mr Metherell said.

"While, according to the TGA, there's not a huge number of blister packs involved, nonetheless the way it's been handled has been a bit low-profile than probably many in the community would expect.

"The Valium tablets were filled with something that wasn't Valium."

Tampering 'not widespread'

The TGA said it was believed that the tampering was not widespread.

The TGA is advising patients to take the Valium to return the drugs to the same pharmacy they were dispensed from to get a full refund or replacement with an alternative medicine.

Pharmacists are being asked to inspect their stock and quarantine all batches of the product before returning them.

Federal vice president of the Australian Medical Association, Dr Tony Bartone, said patients might be at risk of side effects or overdosing if they took the wrong medication.

"It's a concern that they're not getting the medication they believe they are getting, and it's a concern that they maybe having medications that may cause side effects or other issues," he said.

"Especially if they are allergic to some of the components, especially in the case of codeine, and also that there may be an overdosing.

"Anything that interrupts the supply chain or the quality control of medicines in Australia is absolutely a concern and needs to be fully investigated by police."