Taiwan researchers say that side effects of Nexterone (amiodarone) may increase the risk of cancer, particularly among men and those who take high doses of the heart rhythm drug.
In a study published this week by the medical journal Cancer, researchers found that using Nexterone increased the risk for any type of cancer by about 12% for the general population and 20% for men. When large doses of the drug were regularly taken, the risk appeared to increase for both genders, with men still outpacing women.
The study evaluated the link between Nexterone and cancer by looking at the Taiwan National Health Insurance Research database for patients who were treated with amiodarone between 1997 and 2008. Out of 6,418 subjects, 280 developed cancer over a period of about two and a half years.
When larger doses were used, there was a 28% increase in the risk of cancer from Nexterone for both genders in the first year. For men alone, the risk increased to nearly 50% higher than the general population.
“The results of the current study indicate that amiodarone may be associated with an increased risk of incident cancer, especially in males, with a dose-dependent effect,” the researchers concluded. Dose-dependent effects, where the risk of a side effect increases with the amount of a drug taken, is often considered a strong indicator that there is a causal link.
The researchers speculate that a possible reason that Nexterone side effects may increase the cancer risk among men is because women have a 37% higher clearance rate, meaning their bodies get rid of the drug faster. The percentage of body fat may also play a role.
Nexterone is a Baxter drug used for the treatment and prevention of heart rhythm problems including ventricular fibrillation (VF) and hemodynamically unstable ventricular tachycardia (VF). It is administered through an IV. It is also sold under the brand names Cordarone and Pacerone as oral tablets by Wyeth-Ayerst Laboratories and Upsher-Smith Laboratories, respectively.
In 2011, the FDA temporarily limited the use of the cholesterol drug Zocor with all amiodarone-based drugs, due to the risk of myopathy and rhabdomyolysis, a potentially life-threatening muscle injury. However, the FDA reversed its decision later that year, saying there was not enough scientific evidence to support the restriction.
Rhabdomyolysis from Zocor causes muscle fibers to begin to break down, releasing a protein called myoglobin, which can damage the kidneys as they attempt to filter it out of the bloodstream. Symptoms of rhabdomyolysis include muscle cramps, tenderness, stiffness, pain or spasms. The illness is usually reported in patients over 65 years of age or those who have renal impairment or uncontrolled hypothyroidism.