Lecture on Diltiazem (Cardizem)

Introduction

• Medication: Diltiazem (Cardizem)
• Approval: FDA-approved in 1982
• Availability: Generic drug

Mechanism of Action

• Type: Calcium channel blocker
• Targets: Heart and blood vessels
• Action: Inhibits influx of extracellular calcium ions during depolarization
  • Negative inotropic effect: less contractility
  • Negative chronotropic effect: slows heart rate
  • Strong effect on AV node conduction
  • Increased smooth muscle relaxation
    • Result: arterial vasodilation, including coronary arteries
    • Decreased blood pressure
  • Stronger effect on cardiac calcium channels vs. vascular ones

Indications

• Primary Use: Cardiac dysrhythmias (e.g., atrial flutter, afib, PSVT)
  • Classified as a class 4 antiarrhythmic
• Hypertension: Alone or in combo with other antihypertensives
  • Greater effect in hypertensive patients
• Angina: Management of Prinzmetal/vasospastic and chronic stable angina

Contraindications

• Hypersensitivity to diltiazem
• Sick sinus syndrome without a pacemaker
• Second/third degree AV blocks without a pacemaker
• Hypotension, acute myocardial infarction
• Pulmonary congestion
• Caution in older adults with heart failure, hypertrophic obstructive cardiomyopathy, impaired hepatic/renal function
• Specific to IV dose: cardiogenic shock, ventricular tachycardia, recent IV beta blocker therapy
• Wolf-Parkinson-White syndrome: may increase ventricular rate

Adverse Effects

• Headache, dizziness
• Arrhythmias, AV blocks, bradycardia
• Heart failure, hypotension
• Nausea, constipation
• Chronic rash in elderly
• Exacerbation of existing cardiac dysfunction more likely

Dosage and Administration

• IV Push: 5 mg/mL (available in 5, 10, or 25 mL vials, no dilution needed)
• Continuous Infusion: 125 mg in 125 mL D5W or D5 ½ NS
• PO Dosing: Varies widely
• IV Infusions: 5-15 mg/hr; start with 10 mg/hr, titrate to goal
  • Initial bolus: 0.25 mg/kg over 2 min; second bolus: 0.35 mg/kg if needed
• Duration: Should not exceed 24 hours

Pharmacokinetics

• Onset: Less than 2-3 minutes (IV)
• Peak: 2-7 minutes
• Duration: 1-10 hours or length of infusion
• Metabolism: Extensive first-pass liver metabolism
• Excretion: Urine and feces
• Antidote: None available

Nursing Considerations

• Monitor blood pressure and heart rate, especially when starting or adjusting doses
• Continuous ECG monitoring; frequent blood pressure checks
• Withhold dose if systolic BP <90 or HR <60; notify provider
• Avoid grapefruit juice (increases diltiazem levels)
• Monitor liver and renal function (ALT, AST, LDH, bilirubin, ALP)

Conclusion

• Importance of monitoring and dose adjustments
• Patient education on avoiding grapefruit juice
• Relevant lab studies for liver/renal function

Presentation Acknowledgments

• Instructor encourages likes, comments, and subscriptions on video
• Special shout-out to YouTube and Patreon supporters
• Links provided for additional support and merchandise