CARDIZEM LA
Clinical safety rating
cautionComprehensive clinical and safety monograph for CARDIZEM LA (CARDIZEM LA).
Cardizem LA (diltiazem) is a calcium channel blocker that inhibits calcium ion influx across cardiac and smooth muscle cells during depolarization, leading to negative inotropic, chronotropic, and dromotropic effects. It dilates coronary and peripheral arteries, reducing systemic vascular resistance and myocardial oxygen demand.
| Metabolism | Primarily hepatic via CYP3A4; undergoes extensive first-pass metabolism. Metabolites include N-desmethyl diltiazem (active), deacetyl diltiazem, and others. |
| Excretion | Urine (2-4% unchanged, ~40% as metabolites); bile/feces (major route, ~60% as metabolites). |
| Half-life | Terminal elimination half-life: 5-8 hours after oral administration. For extended-release formulations, the half-life is similar but the prolonged absorption phase results in sustained plasma concentrations. |
| Protein binding | 70-80% bound to plasma proteins (mainly albumin). |
| Volume of Distribution | 3-5 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral: ~40% due to extensive first-pass metabolism; intravenous: 100%. |
| Onset of Action | Oral (immediate release): 30-60 minutes; Oral (extended release): 2-3 hours. |
| Duration of Action | Immediate release: 6-8 hours; Extended release (Cardizem LA): 24 hours due to once-daily dosing. |
| Molecular Weight | 414.52 Da |
Oral, 180-360 mg once daily; initiate at 180 mg once daily, titrate to 240 mg, then 300 mg, then 360 mg once daily as needed.
| Dosage form | TABLET, EXTENDED RELEASE |
| Renal impairment | No specific dose adjustment is required for decreased GFR; however, use with caution in severe renal impairment (CrCl <30 mL/min) due to potential accumulation. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B: reduce dose by 50%. Child-Pugh C: use is not recommended. |
| Pediatric use | Safety and efficacy have not been established in pediatric patients; no standard pediatric dosing available. |
| Geriatric use | Initiate at low end of dosing range (180 mg once daily) and titrate slowly due to increased risk of hypotension, bradycardia, and reduced hepatic clearance. |
| 1st trimester | Diltiazem crosses the placenta. Animal studies have shown embryotoxic and fetotoxic effects. Human data are limited; use only if benefit outweighs risk. |
| 2nd trimester | Use only if clearly needed. Monitor for potential fetal effects. Limited human data. |
| 3rd trimester | May cause uterine relaxation and delay labor. Use near term only if benefit outweighs risk. Monitor neonate for bradycardia, hypotension, hypoglycemia. |
Clinical note
Comprehensive clinical and safety monograph for CARDIZEM LA (CARDIZEM LA).
| Placental transfer | Diltiazem crosses the placenta in humans; fetal plasma levels are approximately 40-50% of maternal levels. |
| Breastfeeding | Diltiazem is excreted into breast milk in low concentrations. Based on limited data, it is likely compatible with breastfeeding but monitor infant for potential adverse effects such as bradycardia and hypotension. Use caution. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | Category C. First trimester: No adequate studies in humans; animal studies show embryotoxicity and fetotoxicity at high doses. Second and third trimesters: Risk of fetal bradycardia, hypotension, and growth restriction; avoid use if possible. |
| Fetal Monitoring | Monitor maternal blood pressure, heart rate, and ECG. Fetal heart rate monitoring for bradycardia. Assess fetal growth with ultrasound if used long-term. |
| Fertility Effects | No human data on fertility. Animal studies show no impairment at clinically relevant doses. |
■ FDA Black Box Warning
None.
| Serious Effects |
Sick sinus syndrome (except in presence of functioning ventricular pacemaker)Second- or third-degree AV block (except in presence of functioning ventricular pacemaker)Hypotension (systolic <90 mmHg)Acute myocardial infarction and pulmonary congestionKnown hypersensitivity to diltiazem
| Precautions | Conduction abnormalities: May worsen sinus node dysfunction or AV block, especially in elderly or with beta-blockers., Heart failure: Use with caution in patients with reduced left ventricular function., Hypotension: May cause symptomatic hypotension, especially with concurrent vasodilators., Hepatic impairment: Diltiazem is hepatically metabolized; use with caution in patients with hepatic impairment., Abrupt withdrawal: May precipitate angina or hypertension exacerbation; taper dose., Beta-blocker coadministration: Increased risk of bradycardia, AV block, and hypotension. |
| Food/Dietary | Avoid grapefruit and grapefruit juice as they inhibit CYP3A4 and may increase diltiazem levels. Limit alcohol intake due to additive vasodilation and hypotension risk. No specific food restrictions otherwise, but maintain a heart-healthy diet low in sodium and saturated fats to support blood pressure and angina management. |
| Clinical Pearls | CARDIZEM LA is a once-daily extended-release formulation of diltiazem, a non-dihydropyridine calcium channel blocker. It is useful for hypertension and chronic stable angina. Avoid use in patients with second- or third-degree AV block, sick sinus syndrome without pacemaker, hypotension (SBP <90 mmHg), or acute MI with pulmonary congestion. Monitor heart rate and PR interval, as it can cause bradycardia and AV block. Contraindicated with IV beta-blockers; caution with oral beta-blockers due to additive negative chronotropic effects. CYP3A4 substrate; avoid strong inhibitors/inducers. Do not crush or chew capsules; can sprinkle contents on applesauce for patients with swallowing difficulties. Max antihypertensive effect may take 2 weeks. Withdrawal may cause angina exacerbation; taper if discontinuing. Use with caution in heart failure with reduced ejection fraction (HFrEF) due to negative inotropic effects. |
| Patient Advice | Take exactly as prescribed, usually once daily. Swallow capsule whole; do not crush or chew. If you have trouble swallowing, you may open the capsule and sprinkle the beads on a spoonful of applesauce; swallow immediately without chewing. · This medication helps lower blood pressure and reduce chest pain (angina). It may take up to 2 weeks to see the full effect on blood pressure. Keep taking it even if you feel well. · Avoid drinking grapefruit juice or eating grapefruit while taking this medication as it can increase side effects. · Common side effects include swelling in legs/ankles, headache, dizziness, or flushing. Report slow heartbeat, severe dizziness, fainting, or shortness of breath to your doctor. · Do not stop taking this medication suddenly, as it may worsen chest pain or cause a heart attack. Your doctor will tell you how to taper the dose if needed. · Limit alcohol consumption, as it may increase dizziness or lower blood pressure further. · Inform all healthcare providers you are taking CARDIZEM LA, especially before surgery or dental procedures. |
Loading safety data…