Clinical features

The various calcium channel blockers produce a consistent clinical picture when taken in large doses.

Predictably, the main effects are on the cardiovascular system. The reduced flow of calcium ions across membranes in the myocardium and vascular smooth muscle results in reduced cardiac contractility and vasodilatation. Electrical conduction in the sinoatrial and atrioventricular nodes is also disturbed.

The resulting cardiovascular signs include:

• hypotension - primarily due to vasodilatation
• bradycardia
• arrythmias including asystole

The CNS is also affected. There may be:

• drowsiness
• confusion
• seizures

Gastrointestinal features include nausea and vomiting.