Close observation is necessary in patients with reduced left ventricular function, bradycardia or with a 1st degree AV block detected on the electrocardiogram or aortic stenosis. In addition, caution should be used if diltiazem is used concomitantly with β-blockers or other medicaments that impair cardiac conduction or contractility.
The anaesthesist must be informed of ongoing diltiazem treatment. Depression of cardiac contractility, conductivity and automaticity, as well as the vascular dilatation associated with anaesthetics may be potentiated by calcium channel blockers.
Increase of plasma concentrations of diltiazem may be observed in the elderly and in patients with renal or hepatic insufficiency. The contraindications and precautions should be carefully observed and close monitoring, particularly of heart rate, should be carried out at the beginning of treatment.
Since diltiazem has shown porphyrogenic characteristics in in vitro and animal studies, caution should be exercised in the treatment of patients with acute porphyria.
Calcium channel blocking agents eg, diltiazem, may be associated with mood changes, including depression.
Like other calcium channel antagonists, diltiazem has an inhibitory effect on intestinal motility. Therefore it should be used with caution in patients at risk to develop an intestinal obstruction.
Tablets and controlled-release tablets contain lactose and sucrose. Patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency, fructose intolerance, glucose-galactose malabsorption or sucrase-isomaltase insufficiency should not take Cardil CR.
Effects on the Ability to Drive or Operate Machinery: At the beginning of treatment with diltiazem, the decrease in blood pressure may induce dizziness especially when standing up. If this occurs, the patient should refrain from driving and using machines. After the treatment effects have been stabilised, it is unlikely that diltiazem should affect these capabilities.
Use in Pregnancy: There is very limited data from the use of diltiazem in pregnant patients. Diltiazem has been observed to induce increased fetal mortality and malformations in certain animal species. Diltiazem is therefore not recommended during pregnancy, as well as in women of childbearing potential not using effective contraception.