Cancer patients in the USA should receive a dental examination before receiving treatment with two intravenous bisphosphonates, Novartis’ Aredia (pamidronate disodium) and Zometa (zoledronic acid), because of a risk the drugs may cause a condition known as osteonecrosis of the jaw, in which bone underlying the teeth is destroyed.

In addition, patients receiving the drug should not undergo invasive dental procedures unless absolutely necessary, according to Novartis, which warned of the newly-identified side effect in a letter sent out to healthcare professionals. Aredia and Zometa are given to treat complications of cancer, including tumour-related breakdown of the bones, excessive calcium in the blood and bone metastases.

Labelling to warn of the risk of osteonecrosis of the jaw has been progressively tightened for both products since 2003 as more evidence of the link came to light, and Novartis first warned doctors of the issue last September. As a result, any impact on the products’ sales is expected to be light.

Zometa was first introduced in 2001 and achieved sales in excess of $1 billion dollars for the first time in 2004, continuing to grow with first-quarter 2005 revenues of $296 million, a rise of 17% year-on-year. It has been positioned as a successor to Aredia, which debuted in 1991 and no longer features among Novartis’ top 20 selling products.

- Meanwhile, earlier this week there was better news for Novartis when reported positive results from the Z-FAST clinical trial of Zometa at the American Society of Clinical Oncology meeting. This study showed that the drug, given alongside Novartis’ aromatase inhibitor, Femara (letrozole), was effective in preventing the well-documented bone loss suffered by patients with breast cancer who are treated with the latter drug class.