'Natural' Remedies May Interfere With Clinical Trials

Patients who use them can skew drug safety results, experts warn.

By Steven Reinberg
HealthDay Reporter
Friday, February 9, 2007; 12:00 AM

Copyright © 2007 ScoutNews, LLC. All rights reserved.

FRIDAY, Feb. 9 (HealthDay News) -- Patients in phase 1 cancer trials may be skewing the results if they are also taking vitamins, herbal preparations, minerals and other dietary supplements, researchers report.

More than one-third of patients in these trials report taking these alternative medications, according to a report in the Feb. 10 issue of the Journal of Clinical Oncology.

Phase 1 trials are designed to test the safety of an experimental drug and to determine if there are any harmful side effects. Since the biological activity of herbals and other natural supplements aren't always known, taking them could mask the effect of the drug under study, explained lead author Dr. Christopher Daugherty, an associate professor of medicine at the University of Chicago.

"If anything bad happens to a patient in a phase 1 trial, we attribute it to the experimental drug," Daugherty said. "But much of biologically active complementary and alternative medicines are agents that have not been well studied, and we don't know what their effects are in the body by themselves, let alone when they're combined with experimental drugs," he said.

"If we don't know what the effects of a alternative drug are, or if we don't know the patient is taking it, we can falsely assume that the experimental drug is unsafe or even safe," Daugherty said.

In the study, Daugherty's team interviewed 212 patients with advanced cancer enrolled in phase 1 clinical trials. Patients were interviewed about their use of biologically-based alternative medications.

The team found that 34 percent of patients were taking these supplements, similar to their usage in the general U.S. population. Among the patients, 41 said they were taking vitamins and minerals, such as vitamins A, C, D, E, and B12, selenium, magnesium, zinc, and copper. In addition, 40 patients said they took herbal preparations, including cat's claw, laetrile, St. John's wort, milk thistle, ginseng, and echinacea.

Although patients in phase 1 trials are not supposed to be taking other drugs, Daugherty believes that there are several reasons why the natural concoctions are often overlooked.