Antidepressant users who switch to a higher dose might be having problems with their original prescriptions because they are not taking their medication as often as prescribed, according to a study announced Thursday.
Medco Health Solutions Inc., a pharmacy benefits management company, said it analyzed pharmacy claims by 13 million people who were using antidepressants. It focused on people who used the same dose of one drug for at least six months and then switched to a higher dose, which indicated the original dose was not controlling their symptoms. Based on how often the patients were filling their prescriptions before they increased their dose, Medco said about 30 percent of them took their medication — with the original dose — 80 percent of the time or less.
Medco only analyzed the prescription data and did not investigate the reasons patients were skipping doses of their medications. Dr. David Muzina said patients may skip doses of their antidepressants because of the side effects of the drugs, which can include a decreased sex drive. The stigma surrounding psychiatric treatment can also be a factor in missing doses, he said. Missing a single dose of an antidepressant does not have immediate side effects, he added, so patients may simply forget to take the medication.
Muzina is a former staff psychiatrist with the Cleveland Clinic who joined Medco's research division at the end of 2009, after the study began. He said doctors sometimes fail to make sure patients are taking their medications as often as they are supposed to.
He said patients also sometimes try to make their medications last longer by taking smaller doses than they have been prescribed, although he does not think that was a major factor in the study.