NAPLEX Question of the Week: Drug Interaction?

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JU is a 54 year old male living with HIV who currently presents to his community pharmacist asking for recommendations regarding his allergic rhinitis. He currently takes pravastatin 40mg daily, Symtuza one tablet once daily, and Claritin 10mg daily. He has continued to have significant symptoms with itchy, watery eyes and pronounced rhinorrhea. He wishes to start OTC Flonase based on good things he has heard from some of his friends. What would be the appropriate response?

A. Flonase would be inferior to his Claritin for his allergic rhinitis symptoms so would not be optimal.

B. The Flonase may increase pravastatin levels leading to an increase in musculoskeletal adverse effects.

C. The Symtuza may increase the risk of Cushing's syndrome when given with Flonase. An alternative inhaled corticosteroid should be chosen.

D. There are no significant drug interactions if Flonase is initiated. Begin Flonase therapy. 

Answer with rationale: 

The correct answer is C (making answer D wrong). Symtuza contains four medications: darunavir, cobicistat, emtricitabine, and tenofovir alefenamide. The drug interaction of note here is with cobicistat which may increase the risk of Cushing's syndrome or adrenal suppression, even though this is a topical dosage form, through strong 3A4 inhibition of fluticasoneThe best option would be to avoid fluticasone altogether and give prescription beclomethasone, which should not be subject to this drug interaction and would be a much more logical option than changing the Symtuza therapy. Answer A is incorrect as inhaled corticosteroids are superior to antihistamines for allergic rhinitis symptoms, especially loratadine. Answer B is incorrect as pravastatin is not appreciably metabolized by CYP enzymes. 

If you would like a humorous take on this drug interaction (and a great shout out for ID pharmacists from an ID physician), check out this historical blog here from Paul Sax:

Have a great week!

Dr. B

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.