Calcium Channel Blocker Poisoning - Causes, Effects, Diagnosis, Treatment, and Prevention

What Is a Calcium Channel Blocker?

Calcium channel blocker (CCB) is a drug that lowers blood pressure and treats various cardiovascular diseases. These act as antihypertensive drugs because they work by blocking the calcium channels in the cells of the heart and blood vessels. Calcium causes the contraction of heart muscles and blood vessels by squeezing them. Therefore, calcium channel blockers help relax these arteries and heart muscles.

However, despite being the most common drugs used for cardiovascular conditions, calcium channel blockers, when in excessive dosage beyond the recommended one, can cause toxicity.

This calcium channel blocker toxicity can also be life-threatening as it often leads to various serious complications.

What Are the Causes of Calcium Channel Blocker Poisoning?

• Ingestion of drugs accidentally.

• Intentional calcium channel blocker overdose or ingestion for suicidal purposes can cause a slow heart rate and a decrease in blood pressure.

• Toxicity can also occur due to the interaction of CCB with other medications.

• Excessive drug exposure can occur due to interference with the body’s metabolism.

What Are the Different Types of Calcium Channel Blockers?

Calcium channel blockers are mainly of two types depending on their activities and the heart condition being treated. These include:

• Dihydropyridines

• Amlodipine.

• Nicardipine.

• Nifedipine.

• Felodipine.

• Nimodipine.

• Isradipine.

• Nisoldipine.

• Nondihydropyridines

• Verapamil.

• Diltiazem.

What Are the Uses of Calcium Channel Blockers?

Calcium channel blockers are mainly used to treat high blood pressure and various other symptoms of cardiovascular diseases, such as:

• Chest pain or angina.

• Coronary heart disease.

• Arrhythmia (irregular heartbeats).

• Raynaud’s disease (blood vessel conditions).

• Migraine (headache).

What Are the Symptoms of Calcium Channel Blocker Poisoning?

The symptoms of CCB poisoning include:

• Agitation or hyperactivity.

• Shortness of breath.

• Breathing difficulty.

• Dizziness or lightheadedness.

• Constipation.

• Tingling sensation (numbness) in hands and feet.

• Irregular, slow, or rapid heartbeats.

• Nausea and vomiting.

• Drowsiness.

• Slurred speech.

• Increased blood sugar.

• Extremely low blood pressure or shock.

• Confusion.

• Weakness.

How to Diagnose Calcium Channel Blocker Poisoning?

• Potassium, glucose, bicarbonate, electrolytes, creatinine, and calcium levels.

• If acidosis is present, lactate levels must be checked.

• Crucial monitoring of electrocardiogram (ECG) and pulse oximeter.

• If Digoxin is applicable, Digoxin-level testing must also be done.

What Is the Treatment for Calcium Channel Blocker Poisoning?

Calcium channel blocker poisoning does not have any specific antidote treatment available. However, the condition can be managed according to the mechanism of drug toxicity levels in the body. Some medicines or therapies for treating toxicity include:

• First-line treatment is given immediately by managing the airway, breathing, and assessing the vital signs.

• Continuous monitoring of the cardiac output.

• Laryngoscopy-induced bradycardia and vagally mediated hypotension can be treated with Atropine pre-administration.

• In case of severe toxicity, the patient must be intubated (endotracheal) if symptoms worsen due to deterioration of hemodynamics (blood flow dynamics in the body).

• Gastric lavage (stomach irrigation or pumping) can also be done if the drug is ingested just one hour before the treatment starts.

• In hemodynamically stable patients, gastrointestinal decontamination can occur if the ingested drug is sustained-release.

Pharmacological Treatment:

• Calcium - The administration of calcium is effective in treating hypotension (low blood pressure) because it increases the extracellular concentration of calcium influx. This therapy is not suitable for treating or managing bradycardia (slower than normal heart rate). Overusing calcium to treat calcium channel blocker poisoning is not recommended as it can cause hepatic (liver) necrosis, acute tubular necrosis (damage to the kidney’s tubule cells), splenic infarcts (compromised blood supply to the spleen), or multiorgan failure.

• Insulin - Hyperinsulinemia euglycemia therapy (HIET) treats severe toxicity caused by calcium channel blockers. CCB toxicity can disrupt the glucose levels in the body, reduce insulin secretion, and create resistance against insulin production, leading to metabolic acidosis. This insulin administration therapy can help reverse the condition caused by toxicity.

• Lipid Emulsion Therapy - This therapy helps pull the lipid-soluble drugs Verapamil and Diltiazem in the blood into the lipid phase. This therapy is recommended if other treatments are not responsive or in the case of refractory shock treatment. However, lipid emulsion therapy can also encourage fatty acid energy production and cause fat overload syndrome. It can also disrupt blood glucose and magnesium analysis during CCB toxicity. Thus, the adverse effects of this therapy make it a less recommended treatment choice.

• Methylene Blue - This helps treat refractory shock due to calcium channel blocker toxicity and also helps post-coronary artery bypass vasoplegia. Methylene blue causes bluish saliva, urine, and skin discoloration for almost 24 hours.

• Catecholamines - CCB toxicity can lead to shock and refractory hypotension because of cardiac depression and loss of vascular resistance. Catecholamines can treat such conditions during calcium channel blocker overdose. However, catecholamines are used only after assessing the cardiac performance and shock mechanism during toxicity by CCBs.

• Glucagon - It can help improve cardiac output, heart rate, and reversal of atrioventricular block during calcium channel blocker poisoning. However, the drug can cause vomiting and nausea due to emetic effects.

What Are the Complications Associated With Calcium Channel Blocker Toxicity?

Complications associated with CCB Toxicity include:

• Acute respiratory distress syndrome or ARDS (a serious lung disease that leads to low oxygen supply).

• Refractory shock (persistent hypotension with end-organ dysfunction).

• Myocardial infarction (blood flow blockage to the heart muscles), limb necrosis, Severe hypoperfusion (reduction in the blood flow amounts).

• Cardiac arrest along with pulseless electrical activity (PEA).

Complications due to CCB toxicity treatment:

• Hypokalemia (too low potassium levels in the blood), nausea, vomiting with glucagon.

• Multiorgan failure due to calcium infusion therapy overdose.

• Hypokalemia and hypoglycemia (low blood glucose levels) with insulin therapy or HIET.

• Lipid emulsion therapy can cause pancreatitis (inflammation of the pancreas), ARDS, and fat overload.

What Are the Differential Diagnoses for Calcium Channel Blocker Toxicity?

Hypotension and bradycardia during initial assessment can be linked with other pharmacological agent toxicity, such as:

• Beta-blocker toxicity.

• Digoxin toxicity.

• Clonidine overdose.

• Sedative- hypnotic toxicity.

• Tricyclic antidepressant toxicity.

• Organophosphate poisoning.

• Opiate overdose.

What Is the Prognosis of Calcium Channel Blocker Toxicity?

Prognosis usually depends upon toxicity level in the body, amount of drug ingested, and dysfunction levels of the vital organs due to poisoning.

Various factors affecting prognosis are:

• Multiorgan failure.

• Advanced age.

• Pre-existing medical condition and cardiac function impairment.

• Refractory shock.

Conclusion

Calcium channel blockers are cardiovascular drugs used to treat the adult population with related health conditions, including hypertension. Like any other medication, calcium channel blockers can cause poisoning or toxicity. Therefore, only a prescribed dose must be taken to avoid toxicity and life-threatening incidents. In case of an emergency, the nearest doctor must be consulted immediately.