Which Schizophrenia Drugs Cause Interactions?

Schizophrenia treatments should be managed carefully to avoid harmful drug interactions

(RxWiki News) Antipsychotic drugs may interact with other drugs in harmful ways. Some people with schizophrenia may be at risk for harmful drugs combinations.

A study found that 23 percent of people with schizophrenia were given drugs that could be harmful when taken together. Most antipsychotics are processed by the liver by the same enzyme.

Drug-drug interactions happen when two drugs use the same enzyme. This can cause side effects and can be dangerous for the liver.

"Tell your doctor about all medications you are taking."

Researchers, led by Jeff Jianfei Guo, PhD, at the University of Cincinnati Medical Center, with researchers from Bristol-Meyers Squibb and Lifesynch, looked for number of times people were exposed to possible drug-drug interactions.

They looked at the insurance claims of 27,909 patients with schizophrenia. They looked for how often people were prescribed an antipsychotic and any other drug that might cause an interaction.

Of the people that might have been exposed, about 74 percent had both of their prescriptions filled at the same pharmacy. About 63 percent were exposed by the same physician.

Schizophrenics were most likely to be exposed to possibly harmful interactions by using two different antipsychotics. Haldol (haloperidol) and Zyprexa (olanzapine) given together was the most common.

The researchers looked at other patient factors to see which people might be at the highest risk.

Drug-drug interactions were more likely in women, people who were Caucasian, and people who also had depression.

The authors conclude that new ways to help doctors and pharmacists avoid these types of exposures are needed.

The study only looked for two competing drugs that were prescribed at the same time in patient records. So, it is unclear if the people in this study actually experienced any a drug-drug interactions.

The study was published August 15 in Psychiatric Services. Some of the authors on this study report affiliations with LifeSynch and Bristol-Myers Squibb.

Review Date: 
August 16, 2012