Women with osteoporosis in Europe can now manage the disease with just four injections a year, following approval of a new intravenous formulation of Roche and GlaxoSmithKline’s Bonviva.

The quarterly dosing regimen for Bonviva (ibandronic acid) was approved in the USA in January, where it is sold as Boniva, giving the product the broadest range of dosage regimens of any drug in the bisphosphonate class.

Bisphosphonate drugs such as Bonviva, Merck & Co’s Fosamax (alendronate) and Actonel (risedronate) from Procter & Gamble/Sanofi-Aventis currently represent the gold-standard osteoporosis treatment, but patient adherence is notoriously low because of these drugs' gastrointestinal side-effects and complicated dosing regimens.

The injectable regimen is expected to be particularly useful for people who find it hard to adhere to oral treatment for osteoporosis, as well as those who are taking other drugs for co-existing health problems, although there is still no hard evidence that longer dosing intervals can improve patient compliance in real world settings.

Bonviva was also the first once-monthly oral bisphosphonate to be approved for sale, and can also be taken in a once-daily dose. GSK and Roche are hoping that offering a number of treatment options will help the product capture market share from once-weekly rival Fosamax, the undisputed market leader with sales of $3.2 billion last year.

GSK reported Bonviva/Boniva sales of £18 million ($32m) last year, including £11 million in the last quarter, and the company claims the product is now winning 10% of all new bisphosphonate prescriptions in the USA. Meanwhile, Roche reported annual sales of the product of 86 million Swiss francs ($66m).

The European Union marketing authorisation for Bonviva injection is based on results from a two-year study called DIVA (Dosing IntraVenous Administration), reported at the ECCEO meeting earlier this month.

Another ongoing study, called PERSIST, is seeking to demonstrate that once-monthly dosing of oral Bonviva is superior to weekly oral dosing in terms of patient adherence.