Chapter 29 Angina Q&A (1 of 13) Sample Questions
1. A 57-year-old male patient with shortness of breath, swollen ankle, high blood pressure and exercise-induced angina comes to the pharmacy with a prescription of Digoxin 250 mcg/day. He is already taking Hydrochlorothiazide, Verapamil and Nitro lingual spray PRN. What do you tell his doctor?
- A. Fill the prescription as is.
- B. Change hydrochlorothiazide to furosemide
- C. Decrease the dosage of digoxin
- D. Increase the dosage of digoxin
Tips: Digoxin should be started at (0.0625mg) lower doses in certain selected patients.
Serum concentrations of digitoxin and Digoxin can increase 35% and 44%-75% respectively, in patients concomitantly receiving verapamil. Greater increases are possible in patients with hepatic cirrhosis. In 19 healthy volunteers receiving Digoxin (0.5mg/day) for four weeks, Digoxin AUC increased 51%, steady state serum concentration increased 42%, and peak Digoxin serum concentration increased 45% after two weeks of verapamil (160mg/day for 4 days and 240mg/day for 10 days). The increase usually occurred in less than one week, and was more significant in patients receiving 240 mg/day of verapamil versus 160 mg/day. Several similar cases involving both digitoxin and Digoxin use with verapamil have reported toxicity (including asystole).