Generic formulations of tacrolimus are as effective as the name-brand version, according to a recent study led by the University of Cincinnati.

Researchers enrolled 70 kidney and liver transplant patients into a prospective, blinded, six-way crossover study. Participants underwent transplantation at one of two hospitals — University of Cincinnati Medical Center or The Christ Hospital (Cincinnati).

The scientists used two different types of generic versions of tacrolimus, which is used postoperatively to lower the risk for organ rejection. The versions were dubbed "Generic Hi" and "Generic Lo," categorized by potency, purity and dissolution.

The focus of the study, funded by the U.S. Food and Drug Administration (FDA), was to investigate whether these two disparate tacrolimus generic versions are bioequivalent to the brand name tacrolimus product, Prograf, in stable patients. Participants in the study received either Prograf or one of the two generic versions of tacrolimus.

Lead investigator Rita Alloway, PharmD, UC research professor of medicine and director of transplant clinical research within the UC Department of Internal Medicine presented the team's findings on May 3 at the 2015 American Transplant Congress annual meeting in Philadelphia.

"We found there to be essentially no difference in the formulations between the generics and brand-name version," Alloway said. "In other words, if you were on brand and switched to generic — and you take your medication as instructed — there should be no clinical consequence."

The results of this study are important because clinicians and patients still express concern over the use of generic drugs after organ transplant, even though most of the tacrolimus dispensed 70 percent is generic.

"Most immunosuppressant drugs require individualized dosing and careful management to ensure the proper blood concentrations are maintained," Alloway said. "Too high exposure to these drugs increases the risk of toxicity, overimmunosuppression and cancer in patents. Too low exposure may lead to rejection of the organ by the patient's immune system."

Clinicians often worry that new or generic drugs may differ from name-brand products in quality, pharmacokinetics and therapeutic efficacy. The results from this study should alleviate those fears.

Alloway collaborated with Uwe Christians, M.D., Ph.D., professor of anesthesiology at the University of Colorado; and Sander Vinks, PharmD, Ph.D., UC professor of pediatrics and director of the Division of Clinical Pharmacology at Cincinnati Children's Hospital Medical Center to perform analysis of drug levels, pharmacokinetics and pharmacogenetics.

Alloway's team of researchers will continue the work through another study funded by the FDA. That study looks at patients who are at greater risk for rejection because they require larger doses of tacrolimus to bring blood concentrations to therapeutic levels. The data from that study will help scientists characterize some of the individual factors affecting tacrolimus levels in hope of understanding whether formulation affects this patient population.

The lead author stressed that, despite the team's findings, all patients should still report any concerns or problems with the products to the FDA.