Genetic discovery may reduce guesswork.

• Position: Drug Dosing - Brief article

The discovery of genetic differences affecting up to one-third of the population could take the guesswork out of prescribing the correct dose of 25% of drugs currently on the market, indicate researchers at Ohio State University, Columbus. Scientists found two genetic variants that alter the activity level of an enzyme responsible for processing, or metabolizing, drugs ranging from the painkiller codeine to the breast cancer drug tamoxifen.

Pending additional research, the variants are good candidates for inclusion in an existing biomarker test that guides drug dosing. The current test is designed to determine the enzyme's activity level, or expression, to predict whether a patient will fall into one of four categories: poor, intermediate, extensive, or ultra-rapid metabolizer. Metabolism speed affects how much medicine a patient needs, but there are limits to the existing test. The current biomarker panel is based on variants that have been associated with how patients respond to...