Case Studies (September 2016)

CASE 1

HJ is a 79-year-old woman with adequate renal function (creatinine clearance: 65 mL/min) who presents to a family medical clinic where you work as a pharmacist. She has been taking metformin 1000 mg twice daily and glipizide XL 10 mg daily for approximately 4 months; however, her glycated hemoglobin has remained above goal at 8.3%. Her primary care physician would like to achieve better glycemic control and writes a prescription for canagliflozin 100 mg daily. HJ mentions that she occasionally skips meals due to the demands of caring for her grandchildren.

As the pharmacist, what recommendations do you have for HJ’s physician regarding the initiation of canagliflozin?

CASE 2

CN is a 52-year-old 70-kg man with normal renal function who presents to the hospital with pleuritic chest pain and is given a diagnosis of pulmonary embolism. He is admitted to an inpatient unit, and an order for unfractionated heparin (UFH) is written. On review of his chart, you read that CN received a single dose of oritavancin for cellulitis 3 days ago. The hospital uses activated partial thromboplastin time (aPTT) to monitor UFH therapy, as anti-factor Xa activity testing is not feasible at this facility.

What concerns do you have about the use of UFH in CN?

ANSWERS

Case 1:HJ’s glipizide dose should be reduced to 5 mg XL daily upon initiation of canagliflozin. Although sodium-glucose cotransporter 2 (SGLT2) inhibitors, such as canagliflozin, infrequently cause hypoglycemia when used alone, they may enhance the hypoglycemic effect of sulfonylureas, such as glipizide (as well as other secretagogues or insulin). Canagliflozin’s prescribing information states that a sulfonylurea dose reduction should be considered when an SGLT2 inhibitor is initiated. HJ has at least 1 risk factor for hypoglycemia (eg, advanced age), making a glipizide dose reduction reasonable. HJ should also be counseled on ways to avoid hypoglycemic episodes (eg, eat regular meals) and how to recognize and treat these episodes if they occur.

Case 2:Oritavancin can falsely prolong aPTT for approximately 5 days after administration. This is due to an interaction between oritavancin and a re-agent used in aPTT laboratory testing. Anti-factor Xa activity testing is thought to be unaffected by oritavancin, but is not feasible at some facilities (including the hospital where CN is being treated). Thus, CN’s UFH therapy cannot be safely monitored. CN should be started on an agent that does not require aPTT monitoring (eg, enoxaparin 70 mg subcutaneously every 12 hours).

Read the answers

Dr. Weeda is an outcomes research fellow and Dr. Coleman is professor of pharmacy practice at the University of Connecticut School of Pharmacy in Storrs.

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