Case Studies (November 2016)
What should these pharmacists do?
MJ is a 67-year-old woman who presents to the emergency department complaining of abdominal pain and frequent diarrhea for the past 3 days. She also reports loss of appetite and is febrile, with a temperature of 101.1ºF. The patient has a history of multiple hospital admissions for urinary tract infections, with the most recent one being 3 weeks ago, after which she completed a 7-day course of levofloxacin. MJ’s laboratory findings indicate a white blood cell count of 12,000 cells/mm3 and an albumin level of 3.2 g/dL (inflammation of the bowel wall allows leakage of albumin into the lumen). A urine culture is negative for bacterial growth; however, a glutamate dehydrogenase stool test for Clostridium difficile is positive and is confirmed by polymerase chain reaction assay. MJ’s drug allergies include metronidazole. Her physician would like to initiate therapy with vancomycin and asks if a dose of 1 g intravenously (IV), every 24 hours, would be appropriate.
What do you, the pharmacist, tell the physician?
LD is a 64-year-old, obese Caucasian man who comes to the clinic for a checkup. His medical history includes hypertension and chronic kidney disease. During the visit, LD complains that, over the past few months, he has experienced chronic fatigue, frequent urination, and nocturia. A random blood glucose test reveals a serum glucose level of 203 mg/dL and a glycated hemoglobin (A1C) level of 7.9%. LD is given a diagnosis of type 2 diabetes (T2D). The physician wants to start LD on metformin but notices his serum creatinine level is 1.5 mg/dL (estimated glomerular filtration rate [eGFR]: 50 mL/min/1.73 m2). The physician tells you (the pharmacist) that metformin cannot be used because of LD’s impaired renal function and risk for lactic acidosis. Instead, the physician proposes initiating glyburide.
As the pharmacist, which agent do you recommend for LD?
SEE THE ANSWERS ON PAGE 2. ANSWERS
Case 1: According to the American College of Gastroenterology guidelines, vancomycin is recommended for treating mild to moderate C difficile infections in patients who are intolerant of or allergic to metronidazole. MJ should receive 125 mg orally 4 times daily for 10 days. When vancomycin is given IV, an inadequate amount of drug reaches the colon; therefore, this route of administration should not be used to treat C difficile infection. Oral vancomycin is available in capsule form (Vancocin), but its high cost often limits its use. The pharmacist may instead recommend preparing vancomycin hydrochloric acid (HCl) 25-mg/ mL oral liquid by reconstituting commercially available vancomycin HCl for injection with sterile water. If needed, common flavoring syrups can be added to the solution to improve the taste.
Case 2: The use of metformin is contraindicated in patients with predisposing risk factors for lactic acidosis, including severe renal dysfunction. Previously, the FDA product labeling for metformin included a contraindication for female and male patients with serum creatinine levels ≥1.4 mg/dL and ≥1.5 mg/dL, respectively. Based on studies suggesting metformin is frequently used and efficacious in lowering A1C levels, without a substantial risk of lactic acidosis in patients with mild to moderate renal impairment (eGFR: 45-60 mL/min), the FDA revised metformin’s product labeling. The labeling now states it is contraindicated in patients with an eGFR <30 mL/min, and the initiation of metformin is not recommended in patients with an eGFR between 30 and 45 mL/min. Pharmacologic management of T2D needs to consider the individual patient. Nevertheless, metformin is widely accepted as the preferred first-line oral agent for treating T2D by the American Diabetes Association, the European Association for the Study of Diabetes, The American Association of Clinical Endocrinologists, and the American College of Endocrinology. The pharmacist should explain to LD’s physician that his renal function does not disqualify him from initiating metformin. Moreover, sulfonylureas (including glyburide) are associated with weight gain and significant hypoglycemia. If metformin is started, LD’s renal function should be monitored at follow-up visits.
Mr. Wysocki is a PharmD candidate at the University of Connecticut School of Pharmacy, Storrs, Connecticut. Dr. Weeda is an outcomes research fellow at the University of Connecticut School of Pharmacy. Dr. Coleman is professor of pharmacy practice at the University of Connecticut School of Pharmacy.