diltiazem
Brand: Cardizem, Dilacor XR, Tiazac
Prototype Drug
Drug Class: calcium channel blocker
Drug Family: antihypertensive
Subclass: non-dihydropyridine CCB (benzothiazepine)
Organ Systems: cardiovascular
Mechanism of Action
Non-dihydropyridine CCB; blocks L-type channels in both cardiac tissue and vascular smooth muscle; slows AV conduction and reduces heart rate.
L-type calcium channel (cardiac and vascular)AV node conduction
Indications
- angina
- hypertension
- atrial fibrillation (rate control)
- atrial flutter
- PSVT (IV)
Contraindications
- acute MI with pulmonary congestion
- cardiogenic shock
- second/third degree AV block without pacemaker
- WPW with AF
- concurrent beta-blocker use with IV form
- severe LV dysfunction
Adverse Effects
Common
- bradycardia
- AV block
- constipation
- peripheral edema
- dizziness
Serious
- severe bradycardia
- cardiogenic shock
- heart block
- hepatotoxicity (rare)
Pharmacokinetics (ADME)
| Absorption | 40-67% bioavailability (first-pass) |
| Distribution | moderate Vd |
| Metabolism | extensive hepatic CYP3A4; also CYP2D6 inhibitor |
| Excretion | renal 35%, fecal 65% |
| Half-life | 3-4 hours (IR), 5-10 hours (XR) |
| Onset | 30-60 min oral; minutes IV |
| Peak | 2-4 hours IR |
| Duration | 6-8 hours IR; 24 hours XR |
| Protein Binding | 70-80% |
| Vd | 3-13 L/kg |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| beta-blockers | additive AV block and bradycardia | major |
| cyclosporine | diltiazem inhibits CYP3A4, increasing cyclosporine levels | major |
| simvastatin/lovastatin | CYP3A4 inhibition increases statin exposure | major |
| digoxin | diltiazem increases digoxin levels | major |
Nursing Considerations
- Monitor HR and PR interval continuously during IV infusion
- Do NOT give IV diltiazem with IV beta-blockers (asystole risk)
- Antidote for calcium channel blocker overdose: IV calcium gluconate, glucagon, high-dose insulin
- Constipation is common — bowel regimen for susceptible patients
- IV bolus then infusion for AF rate control
Clinical Pearls
- Non-dihydropyridine: slows AV conduction — used for rate control in AF
- CYP3A4 inhibitor — raises cyclosporine, statin, and other CYP3A4 substrate levels
- Calcium gluconate reverses CCB toxicity
Safety Profile
Pregnancy avoid
Lactation avoid
Renal Adjustment Not required
Hepatic Adjustment Required
TDM Not required
Concordance Terms
Cross-referenced clinical concepts — click any term to see all content where it appears.