Diltiazem

Diltiazem (Cardizem®)

 

Class:
  • Calcium (Ca++) channel blocker
Actions:
  • Slows SA node automaticity (negative chronotropic)
  • Delays AV node conduction
  • Reduces myocardial contractility (negative inotropic)
  • Dilates coronary arteries during variant angina
  • Dilates peripheral arteries reducing afterload
Indications:
  • Dysrhythmias–slows ventricular rate in atrial fibrillation and atrial flutter
  • Dysrhythmias–after adenosine, 2nd line drug for refractory SVT (narrow QRS tachycardias)
  • Variant angina (reduces coronary vasospasms)
  • Hypertension (relaxes smooth muscles in arterial walls)
Pharmacokinetics:
  • Onset: immediately if IV push
  • Peak: (oral) 2 – 3 hours
  • Half-Life: 2 hours (IV), 3.5 – 9 hours (oral)
  • Metabolism:  liver
Adverse Effects:
  • Headache, fatigue, dizziness, nervousness
  • Bradycardia, AV blocks, heart failure, flushing, hypotension, syncope, peripheral edema
  • Nausea, vomiting, constipation, diarrhea, impaired taste
Signs of Toxicity:
  • Hypotension
  • Severe AV block
Contraindications:
  • Hypersensitivity to diltiazem
  • Sick sinus syndrome
  • 2nd or 3rd degree AV blocks
  • Hypotension (systolic BP < 90 mm Hg)
  • Heart failure
  • Safety not established for children, pregnancy, or lactation
Dosages & Routes:
  • PO:  (angina 30 mg q.i.d.) (hypertension 60 – 120 mg sustain-released b.i.d.)
  • Intravenous: (atrial fibrillation 0.25 mg/kg or 15 – 20 mg slow IV bolus over 2 minutes)
  • IV Drip:  5 – 15 mg/hr titrated to appropriate heart rate
Nursing Implications:
  • Drug Interactions:  1) exacerbates AV blocks with digoxin; 2) increases serum digoxin and serum quinidine levels as well as cyclosporine levels; 3) cimetidine increases diltiazem serum levels.
  • Check blood pressure, heart rate, and cardiac monitor prior to administering diltiazem.
  • Assess baseline renal (BUN, Cr) and liver function (AST, ALT) lab tests.
  • Monitor for signs of heart failure (e.g., pulmonary edema, weakness, dyspnea).
  • Provide analgesic for headache.
  • Use caution during position changes to prevent orthostatic hypotension.

 

References:

American Heart Association. (2006). Handbook of Emergency Cardiac Care (p. 50). Salem, MA: AHA.

Lehne, R.A. (2010). Pharmacology for nursing care (7th ed., pp. 483, 486-487, 547-548, 587).  St. Louis: Saunders Elsevier.

Wilson, B.A., Shannon, M.T., Shields, K.M., & Stang, C.L. (2007).  Prentice Hall Nurse's Drug Guide 2007 (pp. 520-522).  Upper Saddle River, NJ: Pearson Prentice Hall.

 

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