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Page: << Prev | 1 | 2 | 3 | Next >> Verapamil, a calcium-channel antagonist drug, is approved by the U.S. Food and Drug Administration for the treatment of cardiac arrhythmias and high blood pressure. The medicine is typically given in doses of 180 to 240 milligrams per day to help ease hypertension.
However, the patients in this study received more than twice that dose for the off-label treatment of their cluster headaches -- 512 milligrams per day on average, and one patient elected to take 1,200 milligrams per day. The treatment protocol involved ramping up the dose from 240 milligrams to as high as 960 milligrams per day, in 80 milligram increments every two weeks, based on EKG findings, side effects, and symptomatic relief.
Many patients may not be getting those kinds of tests to monitor heart function, however: In this study cohort, about 40 percent of patients never got an EKG.
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Given the typical dosage, Sica said he was surprised so many patients were able to tolerate such high amounts of the drug.
"When used in clinical practice for hypertension, the high-end dose is 480 milligrams," said Sica. "Most people cannot tolerate 480."
Dr. Carl Pepine, chief of cardiology at the University of Florida, Gainesville, was also "amazed" at the doses that were tolerated in this study. "The highest dose I ever gave [for cardiology indications] was 680 milligrams. This might give me more encouragement to use the drug at higher dose," he said.
But Sica said he thought cardiac patients -- the typical verapamil users -- were unlikely to tolerate the drug as well as the patients in this study, because verapamil reacts differently in older individuals, who are more likely to have high blood pressure, than in younger patients. The average patient in the United Kingdom study was 44 years old.
According to Sica, two factors would conspire to make older individuals more sensitive to verapamil. First, the metabolism of the drug is age-dependent, meaning that older individuals would tend to have higher blood levels of the drug, because it is cleared more slowly than in younger individuals.
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