Regulator acts on risk alert for bone drugs
Nicola Berkovic Adam Cresswell
AUSTRALIA’S drug regulator has moved to ensure consistent warnings of possible side effects are published for drugs used to treat osteoporosis and bone cancer, after claims some patients were not adequately warned the drugs have been linked to a progressive decay of jaw bones.
The drugs, known as bisphosphonates, are used to treat bone diseases such as osteoporosis and, in much higher doses, cancer that has spread to the bone. They are intended to increase bone density but in rare cases can interfere with normal bone healing in the jaw — a condition called osteonecrosis, which literally means ‘‘ death of the bone’’.
The Therapeutic Goods Administration this week told the ABC’s 7.30 Report it would require companies selling the drugs to provide ‘‘ clearer and more consistent information’’ to consumers of the risk of osteonecrosis of the jaw, or ONJ.
Of the two million Australians treated with the drugs each year, about 500 are affected by the condition, which can cause gums to break down where teeth have been lost or extracted. In extreme situations it can cause shards of jawbone to break off.
However, the Garvan Institute’s director of bone and mineral research, Professor John Eisman, says osteoporosis patients have an extremely low risk of developing ONJ — as low as 1 in 10,000, and possibly as low as 1 in 100,000, according to studies done in Germany.
He said that was because osteoporosis patients were given 5 per cent or less of the dose prescribed to cancer sufferers.
‘‘ Where this bisphosphonate-related condition has been a significant health problem is with the very high doses that are given to people with cancer, where it’s a matter of life and death,’’ Eisman said.
‘‘ That should not be confused with the much rarer and less severe form, which may occur with people who are being treated for osteoporosis.’’
He said osteoporosis sufferers needed treatment to reduce their relatively high risk of fractures and the serious side effects of those, including premature death.
In 2005-06 there were just over two million prescriptions for the various forms of one bisphosphonate drug, alendronate, sold as Fosamax, Alendro and other brands — costing the Pharmaceutical Benefits Scheme nearly $115 million in that year. Other bisphosphonate drugs include risedronate (Actonel), disodium pamidronate (Pamisol, Acredia) and ibadronic acid (Bondronat, Bonviva).
The TGA issued a statement on Wednesday this week saying the bisphosphonate drugs were ‘‘ very clinically useful’’, and the risk of ONJ was rare and had been both recognised for many years. Warnings had been included in printed information for doctors and patients since early 2005.
Following the program, action was being taken to ensure that the warnings were equally clear and explicit across all the many forms and brands of the drugs.
The statement said the risk of ONJ was thought to be linked to injectable forms of the drugs — which usually involve hospital treatment rather than the tablets that are prescribed by a GP.
‘‘ The Adverse Drug Reactions Unit of the TGA and the Adverse Drug Reactions Advisory Committee (ADRAC) have published articles on bisphosphonate-associated osteonecrosis of the jaw in the Australian Adverse Drug Reactions Bulletin , most recently in August 2006,’’ a TGA spokeswoman said.
‘‘ The National Prescribing Service also provided information on this issue in the April 2007 edition of Rational Assessment of Drugs and Research.
The risk of this rare adverse reaction can be greatly reduced by appropriate dental care.
‘‘ The TGA has recently reviewed the Consumer Medicines Information documents of all bisphosphonates to ensure they adequately inform consumers about the need to discuss dental care, symptoms and side effects with their healthcare professional.
‘‘ The TGA and the Australian Drug Evaluation Committee (ADEC) have written to all state and territory medical and dental boards to enlist their help in informing/ warning practitioners.’’
The TGA spokeswoman said all medicines have potential risks, and the balance between the benefits offered by the medicine and the potential risks ‘‘ need to be considered when these products are prescribed’’.