From the FDA Drug Label
The oral LD50s in mice and rats range from 415 to 740 mg/kg and from 560 to 810 mg/kg, respectively. The intravenous LD50s in these species were 60 and 38 mg/kg, respectively. There have been reports of diltiazem overdose in amounts ranging from <1 g to 18 g. Of cases with known outcome, most patients recovered and in cases with a fatal outcome, the majority involved multiple drug ingestion Events observed following diltiazem overdose included bradycardia, hypotension, heart block, and cardiac failure. In the event of overdose or exaggerated response, appropriate supportive measures should be employed in addition to gastrointestinal decontamination. Based on the known pharmacological effects of diltiazem and/or reported clinical experiences, the following measures may be considered: Bradycardia: Administer atropine (0.60 to 1. 0 mg). If there is no response to vagal blockade, administer isoproterenol cautiously. High-Degree AV Block: Treat as for bradycardia above. Fixed high-degree AV block should be treated with cardiac pacing. Cardiac Failure: Administer inotropic agents (isoproterenol, dopamine, or dobutamine) and diuretics. Hypotension: Vasopressors (e.g., dopamine or norepinephrine).
The parameters for holding Cardizem (diltiazem) include:
- Bradycardia: hold if heart rate is less than 60 beats per minute
- Hypotension: hold if systolic blood pressure is less than 90 mmHg
- High-Degree AV Block: hold if AV block is present
- Cardiac Failure: hold if signs of cardiac failure are present
- Overdose: hold if overdose is suspected, and consider gastrointestinal decontamination, atropine, isoproterenol, cardiac pacing, inotropic agents, and vasopressors as needed 1
From the Research
Parameters for Holding Cardizem (Diltiazem)
The parameters for holding Cardizem (diltiazem) can be considered based on several factors, including heart rate, blood pressure, and dosage.
- Heart rate: Studies have shown that diltiazem can decrease elevated baseline heart rate, with an increasing effect at higher initial rates 2, 3, 4.
- Blood pressure: Diltiazem has been shown to lower blood pressure in hypertensive patients 3.
- Dosage: The appropriate dosage of diltiazem can vary depending on the patient's condition and the formulation used. For example, a study found that a weight-based dose of diltiazem ≥ 0.13 mg/kg was associated with improved heart rate control in patients with atrial fibrillation with rapid ventricular rate 4.
Considerations for Holding Diltiazem
When considering holding diltiazem, the following factors should be taken into account:
- Hypotension: Diltiazem can cause hypotension, particularly at high doses 5, 4.
- Bradycardia: Diltiazem can also cause bradycardia, particularly in patients with pre-existing conduction abnormalities 2, 6.
- Concomitant medications: The use of diltiazem with other medications, such as beta blockers or other calcium channel blockers, can increase the risk of adverse effects 2, 6.
Monitoring Parameters
When holding diltiazem, the following parameters should be monitored:
- Heart rate: Closely monitor the patient's heart rate, particularly in patients with pre-existing conduction abnormalities 2, 3, 4.
- Blood pressure: Monitor the patient's blood pressure closely, particularly in patients with hypotension or those taking concomitant medications that can lower blood pressure 5, 3, 4.
- Electrocardiogram (ECG): Monitor the patient's ECG for signs of conduction abnormalities or other adverse effects 2, 3, 6.