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Albany, NY – In today's Academic Minute, Dr. Amit Pai of the Albany College of Pharmacy and Health Sciences explains the problem of adjusting drug dosages for obese patients.
Amit Pai is an associate professor in the Department of Pharmacy Practice at the Albany College of Pharmacy and Health Science. His research focuses on strategies to optimize antimicrobial drug dosing in special populations, such as HIV, Cystic Fibrosis, and Obesity patients.
Dr. Amit Pai - Drug Dosage
Two-thirds of American adults are either overweight or obese. The average weight of an adult today is 180 pounds and 4 million Americans are over 300 pounds. While the weight distribution of the United States has increased, our approach to estimating drug doses has not kept pace.
Drug dosing in obese patients is often an educated guess because clinical trials generally exclude obese patients. As a pharmacist and clinical scientist, I am often asked "Will a 500 milligram dose of a drug work just as well in a 300 pound versus 150 pound adult?" "should we make a weight based dose adjustment." The reality is that using a patient's actual body weight to calculate a dose, will, on average, estimate too high a dose in obese patients. Other equations for estimating body size, such as ideal body weight can have the opposite effect of estimating too low a dose in obese patients.
A new equation that estimates lean body weight or fat free weight appears to hold promise. My group has used this equation to aid drug dosing in adults that weigh up to 450 pounds. Although we have shown success with a few drugs using lean body weight, a universal approach to defining doses in obese patients is unlikely to work for every drug. So the best solution will be to advocate for the inclusion of obese patients in clinical trials. This will ensure that the doses we select are not "too high" or "too low", but "just right".