Diltiazem – A Calcium Channel Blocker for Hypertension & Arrhythmias

 

Diltiazem is a calcium channel blocker used for hypertension, angina, and arrhythmias like atrial fibrillation. Learn about its mechanism, dosage, side effects, contraindications, brand names, and pricing.

Table of Contents:

1. Introduction  

2. Mechanism of Action  

3. Pharmacokinetics & Dynamics  

4. Indications & Drug of Choice  

5. Contraindications  

6. Side Effects  

7. Dosage  

8. Brand Names  

9. Price  

10. Conclusion  

1. Introduction:

*Diltiazem* is a *non-dihydropyridine calcium channel blocker (CCB)* used primarily for managing *hypertension*, *angina*, and *cardiac arrhythmias* like *atrial fibrillation*. It works by relaxing blood vessels and slowing the heart rate, making it ideal for rate control and reducing cardiac workload.

2. Mechanism of Action:

Diltiazem inhibits *L-type calcium channels* in:

- *Cardiac muscle cells*: ↓ heart rate & conduction velocity

- *Vascular smooth muscle*: ↓ peripheral resistance  

This leads to:

- Decreased myocardial oxygen demand  

- Slower AV nodal conduction  

- Lower blood pressure

3. Pharmacokinetics & Dynamics:

| *Absorption* | Well-absorbed orally                

| *Bioavailability* | ~40–60% (first-pass metabolism) 

| *Onset*      | 30–60 min (oral); 3–5 min (IV)      

| *Half-life*  | 3–6 hours (up to 10 hrs extended-release) 

| *Metabolism* | Liver (CYP3A4)                      

| *Excretion*  | Urine and feces                     |

4. Indications & Drug of Choice:

*Indications*

- Hypertension

- Stable or variant angina

- Atrial fibrillation/flutter (rate control)

- Supraventricular tachycardia (SVT)

*Drug of Choice For:*

- *Rate control* in *atrial fibrillation* in patients intolerant to beta-blockers  

- *Coronary artery spasm* (Prinzmetal angina)

 

5. Contraindications:

- Sick sinus syndrome (without pacemaker)  

- Second or third-degree AV block  

- Severe hypotension (SBP <90 mmHg)  

- Acute myocardial infarction with pulmonary congestion  

- Concomitant use with *IV beta-blockers*

6. Side Effects:

*Common:*

- Edema

- Dizziness

- Bradycardia

- Headache

- Fatigue

*Serious:*

- AV block

- Heart failure

- Hepatotoxicity (rare)

- Severe hypotension

7. Dosage:

*Oral (Hypertension/Angina):*

- Initial: *120–180 mg/day*

- Maintenance: Up to *540 mg/day* (extended release)

*IV (Arrhythmia/SVT):*

- Bolus: 0.25 mg/kg over 2 min  

- Repeat (if needed): 0.35 mg/kg after 15 min  

- Maintenance infusion: 5–15 mg/hr

*Adjust dose in hepatic impairment.*

8. Brand Names:

- *Cardizem*  

- *Tiazac*  

- *Dilzem*  

- *Angizem*  

- *Cartia*  

- *Herbesser*  

- *Diltelan*

 

9. Price: 

- *Pakistan*: PKR 20–80/tablet (depends on brand & strength)  

- *India*: INR 10–40/tablet  

- *USA*: 0.50–3/tablet (generic), ~$10–30/vial (IV)

10. Conclusion: 

  

*Diltiazem* is a versatile calcium channel blocker effective in managing both cardiovascular and rhythm disorders. Its *dual action* on cardiac conduction and vascular smooth muscle makes it particularly useful for *atrial fibrillation*, *angina*, and *hypertension*. However, careful monitoring is needed due to its *bradycardic and hypotensive effects*.