Case Studies (June 2016)

CASE 1

GK is a 47-year-old, 80-kg man who presents to the hospital with new-onset atrial fibrillation and a heart rate of 130 beats/min. He is given a bolus of 20 mg (0.25 mg/kg) intravenous (IV) diltiazem over 2 minutes and then is initiated on a diltiazem drip of 10 mg/hr, which is ultimately titrated to a rate of 15 mg/hr for heart rate control. Per the hospital’s policy regarding patients receiving IV diltiazem, GK is receiving care in the intermediate care unit (IMU). GK has received his infusion of diltiazem for the past 24 hours and has not required any supplemental bolus doses or dose adjustments. GK has achieved a desirable heart rate and has no other medical problems that would necessitate remaining in the IMU. The team would like to transfer GK to a medical floor, but this requires conversion of IV diltiazem to oral diltiazem.

As the pharmacist, how would you recommend this conversion be done?

CASE 2

A couple comes to the pharmacy with their 7-yearold son, AA, who is traveling to India next week. (India is known to have chloroquine-resistant malaria.) AA’s parents present a prescription for mefloquine, which they received from a travel clinic 5 weeks ago, but forgot to fill until now. Upon questioning, they tell you that AA is 48 inches tall, weighs 25 kg, has an allergy to amoxicillin, and is up-to-date on all his childhood vaccinations. He is not taking any other medications.

As the pharmacist, do you have any concerns about filling this prescription?

ANSWERS

Case 1:By switching GK from IV diltiazem to oral diltiazem, he can be treated on the medical floor rather than in the IMU. It is common practice to use the following formula to calculate the approximate oral diltiazem dose required: Total daily oral dose of diltiazem = (IV infusion rate [in mg/hr] × 3 + 3) × 10 GK can be started on oral therapy with immediate-release diltiazem, with his total daily dose split into 4 equal doses administered every 6 hours. GK’s recommended oral diltiazem dose is 480 mg/day, equating to approximately 120 mg of immediate-release diltiazem every 6 hours. Although the optimal time to stop the IV infusion before initiating oral therapy is unknown, it is typically recommended that oral diltiazem be initiated approximately 1 hour prior to discontinuing or down-titrating the infusion.

Case 2:Mefloquine, doxycycline, and atovaquone/proguanil can all be used for chloroquine-resistant malaria prophylaxis in children. However, it is recommended to initiate mefloquine at least 2 to 3 weeks before the first exposure to malaria. Because AA is leaving for India in a week, he would not be able to effectively take this medication. Doxycycline is not FDA-approved for children younger than 8 years and, therefore, would not be appropriate. Atovaquone/ proguanil requires initiation only 1 or 2 days before first exposure to malaria; therefore, switching the prescription to this medication is recommended. Pediatric dosing of atovaquone/proguanil is based on body weight, and the recommended dose for AA is 125 mg/50 mg daily, taken as 2 pediatric tablets to create a single daily dose. Atovaquone/proguanil should be administered until 7 days after last exposure.

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Mr. Liu is a PharmD candidate at the University of Connecticut School of Pharmacy, Storrs, Connecticut. Drs. Weeda and Nguyen are outcomes research fellows at the University of Connecticut School of Pharmacy. Dr. Coleman is professor of pharmacy practice at the University of Connecticut School of Pharmacy.

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