From the Guidelines
Diltiazem boluses should be given at least 15 minutes apart to allow for assessment of the patient's response and to minimize the risk of adverse effects. When treating conditions like supraventricular tachycardia, the initial dose of diltiazem is typically 0.25-mg/kg IV bolus over 2 min, as recommended by the 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia 1. Key considerations for diltiazem administration include:
- Initial dose: 0.25-mg/kg IV bolus over 2 min
- Maintenance dose: Infusion at 5–10 mg/h, up to 15 mg/h
- Potential adverse effects: Hypotension, worsening HF in patients with pre-existing ventricular dysfunction, bradycardia, abnormal liver function studies, acute hepatic injury (rare)
- Precautions: AV block greater than first degree or SA node dysfunction (in absence of pacemaker), WPW with AF/atrial flutter, Hypotension, Decompensated systolic HF/LV dysfunction, Drugs with SA and/or AV nodal–blocking properties, Hepatic or renal dysfunction. The 15-minute interval between boluses is crucial because diltiazem's peak effect occurs within 2-7 minutes after administration, and waiting this period ensures you can properly evaluate the full effect of the first dose before administering more medication, as supported by the guideline 1. Patients should be monitored closely for blood pressure changes, heart rate response, and potential side effects during this time.
From the FDA Drug Label
The initial dose of diltiazem hydrochloride injection should be 0. 25 mg/kg actual body weight as a bolus administered over 2 minutes (20 mg is a reasonable dose for the average patient). If response is inadequate, a second dose may be administered after 15 minutes. The second bolus dose of diltiazem hydrochloride injection should be 0. 35 mg/kg actual body weight administered over 2 minutes (25 mg is a reasonable dose for the average patient).
Diltiazem bolus doses should be given at least 15 minutes apart. Subsequent intravenous bolus doses should be individualized for each patient 2.
From the Research
Diltiazem Bolus Administration
- The provided studies do not directly address the specific question of how far apart diltiazem boluses should be given 3, 4, 5, 6, 7.
- However, the studies discuss the administration of diltiazem in various contexts, including its combination with beta-blockers and nitrates for the treatment of angina pectoris and hypertension.
- In one study, diltiazem was administered four times daily, with a mean dose of 340 mg/day, in combination with maximally tolerated doses of beta-blockers and nitrates 4.
- Another study notes that the combination of diltiazem and beta-blocker agents can cause symptomatic bradycardia, even at low doses, and advises caution when using this combination, especially in elderly patients or those with left ventricular dysfunction or antecedent sinoatrial or atrioventricular conduction abnormality 5.
- The studies suggest that diltiazem can be effective in controlling heart rate and reducing angina attacks when used in combination with other medications, but do not provide specific guidance on the administration of diltiazem boluses 6, 7.