Neemsi Paramedic Pharmacology - Diltiazem

Front 1

What is the best-known trade name for diltiazem?

Back 1

Cardizem

Hint 1

There are over twenty brand names for diltiazem including Angizem, Cartia, Diltalen & Tiazac.

Front 2

What is the functional class of diltiazem?

Back 2

Class IV antidysrhythmic (calcium channel blocker)

Hint 2

Like verapamil, diltiazem is a non-dihydropyridine calcium channel blocker. Dihydropyridine calcium channel blockers have only vasodilatory rather than negative inotropic effects.

Front 3

What is the mechanism of action of diltiazem?

Back 3

Inhibits calcium ion influx through slow channels into cells of myocardial and arterial smooth muscle. This causes intracellular calcium to remain at sub-threshold levels that are insufficient to stimulate cell excitation and contraction. It reduces peripheral vascular resistance by inhibiting the contractility of vascular smooth muscle which causes dilation of the coronary arteries. It also inhibits coronary artery spasm. Diltiazem also slows SA and AV node conduction without affecting atrial action potential.

Hint 3

Diltiazem also affects dopaminergic and glutamatergic signalling in the brain and this may explain why it can be used to reduce cocaine cravings.

Front 4

What are the listed indications for diltiazem?

Back 4

- SVT refractory to adenosine
- Rapid A-Fib or A-Flutter

Hint 4

Diltiazem and other calcium channel blockers are also being investigated in the treatment and prophylaxis of migraine.a

Front 5

What are the listed contraindications for diltiazem?

Back 5

- Hypersensitivity
- Sick sinus syndrome
- 2nd and 3rd Degree AV block,
- Hypotension
- WPW
- Wide complex tachycardia

Hint 5

Hypotension may be a symptom of tachydysrhythmia caused by decreased ventricular filling and administration of diltiazem may still be considered. NH protocols allow diltiazem for tachycardic patients who are symptomatic but hemodynamically stable.

Front 6

What are the listed precautions for diltiazem?

Back 6

- Avoid in patients receiving oral beta-blockers
- Monitor for hypotension resulting from peripheral vasodilation.
- Use with caution in CHF

Hint 6

Some sources list PAOD and COPD as relative contraindications.

Front 7

What are the listed side effects for diltiazem?

Back 7

- Chest pain
- Bradycardia
- Hypotension
- Syncope
- CHF
- Dysrhythmias
- N/V
- Headache
- Sweating
- Dizziness
- Dyspnea
- 2nd and 3rd Degree AV block
- Palpitations

Hint 7

Some sources include blurred vision and confusion.

Front 8

What are the listed interactions for diltiazem?

Back 8

Beta-blockers may increase digoxin (sic) levels

Hint 8

Beta blockers and quinidine may interact with diltiazem to increase the likelihood of dysrhythmias and AV node block.

Front 9

What is the dosage and route of diltiazem?

Back 9

Bolus
0.25mg/kg slow IVP, may repeat in 15 minutes at 0.35mg/kg slow IVP

IV Infusion:
5-15mg/hr, titrate to heart rate

Hint 9

NH protocols state that a diltiazem bolus should be administered over two minutes.

Front 10

What are the pharmacokinetics of diltiazem?

Back 10

None listed.

Hint 10

The half-life of diltiazem is approximately seven hours. There is a strong relation between plasma diltiazem concentration and percent heart rate reduction.