Diltiazem

Aka: Diltiazem, Cardizem, Benzothiazapine, Cartia, Taztia, Tiazac

1. See Also
   1. Calcium Channel Blocker
   2. Calcium Channel Blocker Overdose
   3. Dihydropyridine Calcium Channel Blocker (e.g. Amlodipine, Nifedipine)
   4. Verapamil
   5. Mibefradil
2. Class
   1. Non-Dihydropyridine Calcium Channel Blocker
3. Precautions
   1. Write for generic Diltiazem ER to allow pharmacist to substitute between multiple similar ER preparations
      1. (2016) Presc Lett 23(7): 39-40
4. Mechanism
   1. AV Node effects
      1. Slow AV Node Conduction
      2. Prolong AV Node refractory period
   2. Less negative hemodynamic effects than Verapamil
      1. Potent negative chronotropic effect
      2. Minimal negative inotropic effect
      3. Diltiazem effects Left Ventricular Dysfunction less
   3. Coronary vasodilatation
5. Pharmacokinetics
   1. Onset in 2-7 minutes after IV infusion
6. Contraindications
   1. Wolff-Parkinson-White Syndrome with Atrial Fibrillation
      1. Paroxysmal accelerated ventricular response
      2. Risk of progression into Ventricular Fibrillation
   2. Wide Complex Tachycardia (unless supraventricular)
      1. Risk of severe Hypotension
      2. May progress into Ventricular Fibrillation
   3. Sinus Node or AV Node dysfunction without Pacemaker
      1. AV Block
      2. Sick Sinus Syndrome
   4. Severe Congestive Heart Failure
   5. Concurrent Intravenous Beta Blocker use
7. Indications
   1. Hypertension
      1. Consider Dihydropyridine Calcium Channel Blocker (e.g. Amlodipine) instead if Heart Rate control not needed
   2. Atrial Fibrillation with Rapid Ventricular Response
      1. Highly effective at controlling ventricular rate
   3. Paroxysmal Supraventricular Tachycardia
      1. Less studied than Verapamil for PSVT
   4. Supraventricular Tachycardia
      1. Terminates AV Node reentry Tachycardias
8. Dosing: Rapid Atrial Fibrillation or PSVT
   1. Regimen 1: One Bolus and then maintenance
      1. Bolus: 0.25 mg/kg (to 20 mg) IV over 2 minutes
      2. Maintenance: 10 mg/hour titrated to Heart Rate (typically 5-15 mg/hour)
      3. Mnemonic: Rule of 15 for patient weight of 70 kg
         1. First: 15 mg IV over 2 minutes, then infusion at 15 mg/hour
   2. Regimen 2: Two boluses and then maintenance
      1. Bolus One: 0.25 mg/kg (to 20 mg) IV over 2 minutes
      2. Bolus Two: 0.35 mg/kg (to 25 mg) IV over 2 minutes starting 15 minutes after first bolus
      3. Maintenance: 10 mg/hour titrated to Heart Rate (typically 5-15 mg/hour)
   3. Regimen 3: Hypotensive patient
      1. "Bolus": 2.5 mg/min over 10-20 min infusion
         1. http://ehced.org/wp-content/site/Drips/dilt-load.pdf
      2. Maintenance: 5 mg/hour titrated as Blood Pressure allows to Heart Rate (typically 5-15 mg/hour)
      3. Pretreating with Calcium is unlikely to benefit Blood Pressure
         1. At best may offer transient Blood Pressure increase for 10 minutes (secondary to Catecholamine surge)
         2. Calcium infusion could be considered in Hypocalcemia (e.g. Calcium Chloride 0.5 to 1 g IV)
         3. Kolkebeck (2004) J Emerg Med 26(4): 395-400 [PubMed]
   4. Oral dosing after intravenous rate control
      1. Consider Beta Blocker for chronic rate control (more efficacious than oral Diltiazem)
      2. Diltiazem regular 30-60 mg orally four times daily as a start (titrating to 120 to 360 mg daily)
9. Dosing: Hypertension
   1. Regular: 30 mg orally four times daily (MAX 360 mg/day)
   2. Extended: 180-240 mg orally daily (MAX 540 mg/day)
      1. Long-acting formulations have variable release mechanisms and dosing regimens vary between products
10. Adverse Effects
    1. See Calcium Channel Blocker
11. References
    1. (2022) Presc Lett 29(11): 64-5