Signs and symptoms
Most people who have taken too much of a calcium channel blocker, especially diltiazem, get slow heart rate and low blood pressure (vasodilatory shock). This can progress to the heart stopping altogether. CCBs of the dihydropyridine group, as well as flunarizine, predominantly cause reflex tachycardia as a reaction to the low blood pressure.Other potential symptoms include: nausea and vomiting, a decreased level of consciousness, and breathing difficulties. Symptoms usually begin within 6 hours of taking the medication by mouth. With extended release formulations symptoms may not occur for up to a day. Seizures are rare in adults but in children occur more often. Hypocalcaemia may also occur. Cause
Calcium channel blockers, also known as calcium channel antagonists, are widely used for a number of health conditions. Thus they are commonly present in many peoples homes. In young children one pill may cause serious health problems and potentially death. The calcium channel blocker that caused the greatest number of deaths in 2010 in the United States was verapamil. This agent is believed to cause more heart problems than many of the others. Diagnosis
A blood or urine test to diagnose overdose is not generally available. CCB overdose may cause high blood sugar levels, and this is often a sign of how severe the problem will become. Electrocardiogram
CCB toxicity can cause a number of electrocardiogram abnormalities with a low sinus rhythm being the most common. Others include: QT prolongation, bundle branch block, first-degree atrioventricular block, and even sinus tachycardia.
Differential
It may not be possible to tell the difference between beta blocker toxicity and calcium channel blocker overdose based on signs and symptoms. Management
The medical management of CCB toxicity may be difficult. It may not improve with the usual treatments used for a low blood pressure and a slow heart rate. In those who have no symptoms or signs six hours following taking an immediate release formulation and 24 hours after taking an extended release formulation need no further medical treatment. Detoxification
Activated charcoal is recommended if it can be given within an hour or two of taking the calcium channel blockers. In those who have taken an extended release formulation of a CCB but are otherwise doing fine, whole bowel irrigation with polyethylene glycol may be useful. Causing vomiting by the use of medications such as ipecac is not recommended. Insulin
High doses of intravenous insulin with glucose may be useful and are a first line treatment in overdoses. As this treatment may cause a drop in blood sugar and blood potassium levels, these should be monitored closely. Other
Intravenous calcium gluconate or calcium chloride is considered a specific antidotes. Slow heart rate can be treated with atropine and sympathomimetics. Low blood pressure is treated with vasopressors such as adrenaline.There is tentative clinical evidence and good theoretical evidence of the benefit of lipid emulsion in severe overdoses of CCBs. Methylene blue may also be used for those with low blood pressure that does not respond to other treatments.