Pharmacy researcher launches studies of how genetic variations may affect individual patient responses to heart drugs

Armed with three grants totaling more than a half million dollars, University of Florida pharmacy professor Julie Johnson, Pharm.D., is investigating how genetic variations may influence how individuals respond to drugs commonly used to treat heart and blood vessel diseases.

Beta-blocker drugs, frequently used to treat heart failure, are the subject of one study, funded by a grant of $303,058 from Princeton, N.J. based Orchid Biosciences Inc. Beta blockers are given to patients in heart failure to help reduce the work of the heart by blocking its response to the stress hormone adrenaline. These drugs specifically block the beta adrenergic receptors found on cells of the heart and blood vessels.

Johnson, a professor in the department of pharmacy practice, is examining the relationship between patients’ tolerance of beta-blocker therapy and variations in the structure of the beta2-adrenergic receptor gene inherited by the individual. Her studies also are aimed at determining whether there is a relationship between genetic variations and certain changes affecting the heart’s left ventricle in response to beta-blocker therapy.

In a second research project, funded by a $73,317 grant from Orchid Biosciences, Johnson seeks to determine whether genetic variations in the adrenergic receptors, as well as variable forms of a specific protein (the G protein), may affect individual responses to a drug called dobutamine. This medication is given intravenously to patients in intensive care to support the work of a weak heart. The same drug is given to patients during stress testing to aid diagnosis of ischemia, a disease characterized by narrowing or blockage of coronary arteries.

With the support of a $143,000 grant from Sankyo Pharma Development, Johnson also is investigating how genetic variations may influence how individuals respond to a class of drugs called angiotensin II Type I receptor blockers (ARBs). Antiotensin II is a hormone that can act to increase blood pressure; ARB drugs block the action of this hormone and therefore are useful in treating high blood pressure and heart failure.

Johnson is conducting her cardiovascular drug research in collaboration with several faculty in cardiology at UF’s College of Medicine.