The Ultimate in Drug Adherence

Lots of people who have osteoporosis and should be taking medication regularly to prevent it worsening don’t take their meds. The bisphosphonates are a class of drugs that slow the destruction of bone that occurs in osteoporosis; the original representative was a daily tablet – alendronate, or Fosamax®. To avoid irritation of the lower end of the esophagus (gullet), patients were advised to remain sitting or standing for 30 minutes after taking the drug. Because of this inconvenience, drug adherence (regularity in taking a prescribed medication) was not high. So a once-a-week bisphosphonate was introduced. Easier to remember (?), less inconvenient. However, adherence to this type of medication is still poor. Recently, a once-a-month tablet has become available – ibandronate, or Boniva®.

Now we have the ultimate in aid to adherence – a once a year intravenous infusion. Zoledronic acid (Zometa®) given once-a-year effectively reduces the risk for vertebral and hip fractures in patients with osteoporosis, according to the results of a double-blind placebo-controlled study published in the New England Journal of Medicine. Over 3,800 patients given the infusion were compared with a similar number of subjects given a placebo. Their average age was 73, and they were followed for 3 years. Zoledronic acid was associated with a 70% reduction in f fractures, compared with 10% in those who got the placebo.

The only fly in the ointment was an increased number of cases of atrial fibrillation in the patients taking the zoledronic acid – 50 vs. 20 in the placebo group. At the least, this will mean a warning in the product labeling. At worst, it will prevent approval by the FDA. We shall see. The benefits are obvious, but the risks are not yet adequately quantified. And adherence? How many will come back for a second infusion?