NAPLEX Question of the Week: Potency and Statins

We hear the term "potency" a lot with regards to drug therapy. How can we apply this principle to the exam and ultimately clinical practice?

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You are an internal medicine clinic pharmacist practicing at the VA medical center. During clinic one afternoon an internal medicine resident inquires of you regarding relative potency of various HMG-CoA reductase inhibitors and LDL cholesterol lowering.

Rank the following HMG-CoA reductase inhibitors effects on LDL cholesterol from least to most potent. Assume a 20mg dosage for each agent.

A. Atorvastatin

B. Pravastatin

C. Rosuvastatin

D. Simvastatin

Answer with rationale:

The correct answer is B-D-A-C. HMG-CoA reductase inhibitors (statins) are some of the most prescribed agents in medicine due to their beneficial effects on cholesterol and more importantly outcomes such as nonfatal MI, stroke, and overall mortality. Typically statins are recommended in a number of groups and discussed as "intensity" rather than potency but essentially this is the same idea. Rosuvastatin is the most potent statin followed by atorvastatin, simvastatin, and pravastatin at equivalent doses. High "potent" or intensity statins are recommended for the highest cardiovascular risk groups in order to decrease their risk of morbidity and mortality.

Ranking question are inherently subject to mistakes in selecting the correct order. Be sure and understand exactly what the question is asking. If this question would have been "Rank the following statins in order from lowest to highest dose required to achieve equivalent LDL lowering" then the order would be reversed because Crestor due to its highest potency would require the lowest dose to achieve LDL lowering.

Christopher M. Bland

Clinical Professor, University of Georgia College of Pharmacy

Dr. Christopher M. Bland is a Clinical Professor at the University of Georgia College of Pharmacy at the Southeast GA campus in Savannah, GA. Dr. Bland has over 20 years of academic and clinical experience in a number of clinical areas. He is a Fellow of both the Infectious Diseases Society of America as well as the American College of Clinical Pharmacy. He is co-founder of the Southeastern Research Group Endeavor, SERGE-45, with over 80 practitioners across 14 states involved. Dr. Bland serves as Associate Editor for the NAPLEX Review Guide 4th edition as well as Editor-In-Chief for the Question of the Week. He has provided live, interactive reviews for more than 10 Colleges/Schools of Pharmacy over the course of his career.