Dilzem Special Precautions

Cardiac Conduction: Diltiazem prolongs AV node refractory periods without significantly prolonging sinus node recovery time, except in patients with sick sinus syndrome. This effect may rarely result in abnormally slow heart rates (particularly in patients with sick sinus syndrome) or second- or third-degree AV block. Concomitant use of diltiazem with beta-blockers or digitalis may result in additive effects on cardiac conduction (see Interactions).
Congestive Heart Failure: Although diltiazem has a negative inotropic effect in isolated animal tissue preparations, hemodynamic studies in humans with normal ventricular function have not shown a reduction in either cardiac index or in consistent negative effects on contractility (dp/dt). Experience with diltiazem used alone or in combination with beta-blockers in patients with impaired ventricular function is very limited. Caution should be exercised when using the drug in such patients.
Hypotension: Decreases in blood pressure associated with diltiazem therapy may occasionally result in symptomatic hypotension.
Acute Hepatic Injury: In rare instances, significant elevations in enzymes such as alkaline phosphatase, lactate dehydrogenase (LDH), serum glutamic oxaloacetic transaminase (SGOT), serum glutamic-pyruvic transaminase (SGPT), and other phenomena consistent with acute hepatic injury have been noted. These reactions have been reversible upon discontinuation of drug therapy.
Laboratory Monitoring: Diltiazem hydrochloride is extensively metabolized by the liver and excreted by the kidneys and in the bile. As with any drug given over prolonged periods, laboratory parameters should be monitored at regular intervals.
General: Dermatological events may be transient and may disappear despite continued use of diltiazem. However, skin eruptions progressing to erythema multiforme and/or exfoliative dermatitis (Epidermal necrolysis) have also been infrequently reported. Should a dermatological reaction persist, the drug should be discontinued (see Adverse Reactions).
The drug should be used with caution in patients with impaired renal or hepatic function.
Effects on Ability to Drive and Use Machines: The effect of diltiazem on the ability to drive or use machinery has not been systematically evaluated.