dihydropyridines and Shock

Animal studies and human case reports show promise in using lipid rescue to treat refractory calcium channel antagonist toxicity. However, the majority of research and clinical experience has focused on non-dihydropyridine agents. Thus, we sought to investigate the value of lipid emulsion (ILE) therapy for dihydropyridine-induced shock. This IACUC-approved study utilized seven swine that were sedated with alpha-chloralose, mechanically ventilated, and instrumented for drug delivery and hemodynamic measures. After stabilization and basal measures, nifedipine (0.01875 mg/kg/min) was infused until imminent cardiac arrest (seizure, end tidal CO2 < 10 mmHg, bradydysrhythmia, or pulseless electrical activity). Animals then received a 7 mL/kg bolus of 20% lipid emulsion via central catheter. Lipid circulation was visually confirmed by the presence of fat in peripheral arterial blood. Hemodynamics were continuously monitored until 10 min after lipid bolus. Surviving animals were euthanized. Pre- and post-lipid treatment parameters were analyzed using the Wilxocon signed rank test (p <0.05 significant). Nifedipine toxicity was characterized by vasodilatory hypotension, impaired vascular contractility, and tachycardia with terminal bradycardia. The median time to imminent cardiac arrest from start of nifedipine infusion was 218 min. Lipid treatment did not improve hemodynamics or restore circulation in any animal. There was no benefit from lipid rescue in this model of nifedipine toxicity. Further study of ILE for dihydropyridine toxicity is warranted but initial animal model results are not promising.

Topics: Animals; Blood Glucose; Blood Pressure; Bradycardia; Calcium Channel Blockers; Dihydropyridines; Disease Models, Animal; Fat Emulsions, Intravenous; Female; Heart Arrest, Induced; Humans; Metabolome; Myocardial Contraction; Nifedipine; Pilot Projects; Shock; Swine; Tachycardia

Overdose with calcium channel blockers is uncommon, but is associated with high mortality. The management includes fluid resuscitation, calcium gluconate, glucagon, vasopressors, and high-dose insulin-euglycemia therapy. We describe a rare case of massive overdose of lercanidipine with shock, refractory to conventional therapies and multi-organ failure. Charcoal hemoperfusion with continuous venovenous hemodiafiltration was then used successfully and the patient showed remarkable recovery.

Topics: Aged; Amlodipine; Antihypertensive Agents; Calcium Channel Blockers; Charcoal; Dihydropyridines; Drug Overdose; Hemodiafiltration; Hemoperfusion; Humans; Male; Multiple Organ Failure; Shock; Time Factors; Treatment Outcome

Splanchnic artery occlusion (SAO) with subsequent reperfusion elicits a severe form of circulatory shock. To study the possible involvement of Ca2+ overload in this shock state, we have examined the effects of benidipine, a novel long-acting calcium antagonist, in a rat model of SAO shock, focusing on endothelial damage. Pentobarbital-anesthetized rats were subjected to 90-min occlusion of both the celiac and superior mesenteric arteries, followed by reperfusion. Rats given only the vehicle for benidipine developed hypotension following reperfusion, and only 7 of 16 rats (44%) survived 2 hr of reperfusion. In isolated superior mesenteric rings from SAO-shock rats, the EDRF-dependent dilator response to acetylcholine (ACh) (100 mM) was severely depressed (9% vs. 97% in control artery rings, P less than 0.001), whereas the EDRF-independent dilator response to acidified NaNO2 (100 microM) was unchanged. By contrast, 90% (9 of 10, P less than 0.05) rats treated with benidipine 45 min postocclusion (3 micrograms/kg, i.v.) survived 2 hr, and the dilator response to ACh was markedly improved (49% of initial, P less than 0.001). SAO-shock rats treated with benidipine also exhibited significantly attenuated accumulation of free amino-nitrogenous compounds (5.5 vs. 7.9 U/ml, P less than 0.05) and myocardial depressant factor (34 vs. 62 U/ml, P less than 0.001). These results suggest that endothelial damage plays a role in the pathogenesis of shock following bowel ischemia and reperfusion and that Ca(2+)-entry blockade improves endothelial function, which is involved in the amelioration of the shock state.

Topics: Acetylcholine; Animals; Blood Pressure; Calcium Channel Blockers; Celiac Artery; Constriction; Dihydropyridines; Endothelium, Vascular; Ischemia; Kinetics; Male; Mesenteric Arteries; Myocardial Depressant Factor; Rats; Rats, Inbred Strains; Shock; Vasodilation