Monday Pharmaceutical Mystery: April 22

What is causing KS's blood pressure to increase, despite maintaining a similar routine?

KS is a male who is age 54 years, and is a regular patient at your pharmacy. He has hypertension and takes aliskiren (Tekturna, Noden Pharma) 150 mg daily. KS is compliant with his medication, as determined on a recent medication therapy management (MTM) consult. He uses a pill organizer and fills his prescription on time. Besides aliskiren, he does not take any other medications. He maintains a healthy weight and reports that he exercises regularly, manages stress, limits salt, and avoids alcohol, all in an attempt to help control his blood pressure. KS has been monitoring his blood pressure daily for about 1 year, and recently noticed that despite no other changes in routine, his blood pressure readings have been higher recently.

Mystery: What is causing KS’s blood pressure to increase, despite maintaining a similar routine?

Solution: Upon further speaking with KS, he mentions that he has been making smoothies every day after his morning workout. In the smoothies, he uses frozen fruit and apple juice or orange juice. However, both of these juices have been reported to interact with aliskiren. Orange juice and apple juice (as well as grapefruit juice) greatly reduce the plasma concentration and renin-inhibiting effect of aliskiren. The mechanism is likely by inhibiting OATP2B1-mediated influx in the small intestine. It is recommended to avoid orange, grapefruit, and apple juices while taking aliskiren.

Reference

US National Library of Medicine National Institutes of Health: Orange and apple juice greatly reduce the plasma concentrations of the OATP2B1 substrate aliskiren. Br J Clin Pharmacol. 2011 May; 71(5): 718—726. doi: 10.1111/j.1365-2125.2010.03898.x. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3093077/. Accessed April 21, 2019.