The Medicines and Healthcare products Regulatory Agency (MHRA) has published Drug Safety Update for October 2011 (PDF).
This issue contains drug safety information advising clinicians of the new evidence of cardiovascular, hepatic and pulmonary risks posed by dronedarone (Multaq®). A review has concluded that the benefits of treatment continue to outweigh the risks for the maintenance of sinus rhythm after successful cardioversion in a limited population of patients with paroxysmal or persistent atrial fibrillation. However, in light of safety concerns dronedarone should only be prescribed after other treatment options have been considered.
The launch of buccal midazolam (Buccolam®) is also discussed. This new product may be a suitable alternative to rectal diazepam for the treatment of prolonged seizures in children. This product has been used previously in unlicensed forms which may have contained different strengths. Care is urged when changing to use of the licensed product to ensure equivalent doses are used.
The hot topic section contains a review of recent analyses of the cardiovascular safety of calcium and vitamin D supplements. This review notes that the recent analyses do not provide conclusive evidence of clinically significant harm due to limitations in the studies. The main limitation noted is that despite the increase in myocardial infarctions there was no increase in overall mortality.
The stop press section reminds clinicians to avoid using Enzira, Inflexal V and Viroflu influenza vaccines in children aged under 5 years due to an increase in the risk of fever and febrile convulsions.
This section also advises readers that use of aqueous calamine cream prior to an x-ray may result in the incorrect identification of intramammary calcifications due to the zinc oxide content. Since such calcifications are an indicator of early breast cancer the implications of use prior to x-rays may be significant.
Action: Clinicians will find this publication to be a useful review of current issues in drug safety.
The Archives of Internal Medicine has published the results of an observational study that has linked the use of some vitamin and mineral supplements with an increased risk of mortality. This has been reported in general media (BBC).
This study reviewed data from the Iowa Women's Health Study. 38,772 women with an average age of 61 years self-reported supplement use at three time points (1986, 1997 and 2004). 15,548 deaths were identified through State and National recording systems to the end of 2008.
After correction for several factors including age, smoking status, body mass index, hypertension, diabetes and education it was noted that use of multivitamins, vitamin B6, folic acid, cooper iron, magnesium and zinc were all associated with an increased risk of mortality when compared with non-users. Only one of the fifteen supplements analysed (calcium) was linked to a decrease in mortality.
The study authors note several limitations in their findings. Firstly, the participants in the study were exclusively women and 99.2% were white and 98.6% were postmenopausal. The results of this analysis may therefore not be applicable to other patient groups.
Secondly, the data are observational and there may be residual confounding factors that were not corrected for, such as underlying illnesses. Finally, the study did not analyse the impact of these supplements on quality of life however it has raised concerns about long-term safety.
The authors of the study state that there is "little justification for the general and widespread use of dietary supplements" and that use should be based upon a "strong medically based cause, such as symptomatic nutrient deficiency disease".
Action: Clinicians should be aware of this study. Individual patients who consume a well balanced diet can be advised that supplements are unnecessary and may be harmful.
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