Cardiotoxicity characterized by Hypotension & Bradycardia. In overdose, β-blockers and CCBs often have similar presentation and there is much overlap in treatment. In an overdose situation, receptor selectivity is lost, and effects not normally seen at therapeutic doses can occur. Within the pancreas, calcium channel antagonism results in decreased insulin secretion. As DHPs-type CCBs only act peripherally, the vasodilation they cause may induce a compensatory increase in the heart rate. Reduced afterload and systemic blood pressure. In vascular smooth muscle – CCBs prevent arterial contraction. CCBs exhibit different selectivity for cardiac vs vascular smooth muscle cell channels.Ĩ In myocardial tissue – Negative inotropy (contractility) chronotropy ( rate), and dromotropy (conduction velocity). CCBs prevent the opening of these voltage-gated calcium channels and reduce calcium entry into cells during phase 2 of an action potential.
Myocardial cells, smooth muscle cells and β-islet cells of the pancreas. Highly lipid soluble agents such as propranolol cross the BBB and can result in unwanted CNS effects.ħ CCB pharmacology Voltage-gated calcium channels are found in The protective effects of ISA do not completely prevent cardiovascular toxicity following overdose. β – blockers with Membrane stabilizing activity (MSA) (eg, propranolol, acebutolol) inhibit myocardial fast sodium channels, which can result in a widened QRS interval and may potentiate other dysrhythmias β - blockers with Intrinsic sympathomimetic activity (ISA) shows partial agonist effect at the beta receptor site, resulting in less bradycardia and hypotension. β-3 - primarily affect lypolysis and may have effects on cardiac inotropy.Ĥ Some β-blockers may antagonize cardiac sodium channels, producing quinidine-like effects that will increase toxicity in overdose. β-2 - regulate smooth muscle tone and influence vascular and bronchiolar relaxation. Β-1 - regulate myocardial tissue and affect the rate of contraction via impulse conduction. CCBs and β-blockers accounted for 37% of these exposures and the majority of cases resulting in death.
cardiovascular drugs the fifth leading cause of death in the TESS database. consultant Max Super Speciality Hospital Patparganj, New DelhiĢ 2004 Toxic Exposure Surveillance System (TESS) report -ģ% (n = 74,145) of the total exposures due to cardiovascular medications. 1 BETA- BLOCKERS & CALCIUM CHANNEL BLOCKER TOXICITYĭr.