Evaluation of intravenous lipid emulsion on haloperidol-induced hypotension in rabbits

Effect of Intravenous Lipid Emulsion on Clozapine Acute Toxicity in Rats

Objectives

Many studies have been reported the efficacy of intravenous lipid emulsion (ILE) as an antidote on acute lipophilic drug toxicity. Clozapine, highly lipophilic dibenzodiazepine neuroleptics, is an important medication in the schizophrenia therapy regimen. Acute intoxication with antipsychotics is one of the main reasons for the referral of poisoned patients to the hospital. We expected that ILE could be used for the therapy of acute clozapine intoxicated patients.

Methods

We used two groups of consisting of six male rats. Both groups received a toxic dose of clozapine (40 mg/kg) intravenously, via the tail vein. After 15 minutes, they were treated with intravenous infusion of 18.6 mg/kg normal saline (NS group), or 18.6 mg/kg ILE 20% (ILE group). We evaluated blood pressure (BP) and heart rate by power lab apparatus through the tail artery, ataxia by a rat rotary circle, seizure scores and death in multiple times after starting clozapine administration. For biochemical and pathological evaluations the samples of tissue and blood were taken.

Results

Our results demonstrated that ILE 20% could return hypotension-induced clozapine better than normal saline. Furthermore, ataxia and seizure have rectified more rapidly and deaths reduced. Clozapine administration causes pancreatitis and lung injury but fat emulsion did not show an optimal effect on tissue damages caused by clozapine toxicity.

Conclusion

In conclusion, ILE can remove toxic signs of clozapine same as other lipophilic medicines, however, clinical uses of ILE for this intention requires more appraisement to determine the precise implication and safety.

Liquid Chromatography Analysis of Clozapine in Rat Brain Tissue, Using its Molecularly Imprinted Polymer after Administration of Toxic Dose of Drug and Lipid Emulsion Therapy

Background:

Molecularly imprinted polymers (MIPs) are synthetic polymers that have a selective site for a given analyte, or a group of structurally related compounds, that make them ideal polymers to be used in separation processes.

Objective:

An optimized molecularly imprinted polymer was selected and applied for selective extraction and analysis of clozapine in rat brain tissue.

Methods:

A molecularly imprinted solid-phase extraction (MISPE) method was developed for preconcentration and cleanup of clozapine in rat brain samples before HPLC-UV analysis. The extraction and analytical process was calibrated in the range of 0.025-100 ppm. Clozapine recovery in this MISPE process was calculated between 99.40 and 102.96%. The limit of detection (LOD) and the limit of quantification (LOQ) of the assay were 0.003 and 0.025 ppm, respectively. Intra-day precision values for clozapine concentrations of 0.125 and 0.025 ppm were 5.30 and 3.55%, whereas inter-day precision values of these concentrations were 9.23 and 6.15%, respectively. In this study, the effect of lipid emulsion infusion in reducing the brain concentration of drug was also evaluated.

Results:

The data indicated that calibrated method was successfully applied for the analysis of clozapine in the real rat brain samples after administration of a toxic dose to animal. Finally, the efficacy of lipid emulsion therapy in reducing the brain tissue concentration of clozapine after toxic administration of drug was determined.

Conclusion:

The proposed MISPE method could be applied in the extraction and preconcentration before HPLC-UV analysis of clozapine in rat brain tissue.

Disruption of dopamine D1/D2 receptor complex is involved in the function of haloperidol in cardiac H9c2 cells

AIMS

Haloperidol is an antipsychotic agent and acts as dopamine D2 receptor (D2R) antagonist, as a prototypical ligand of sigma1 receptors (Sig1R) and it increases expression of type 1 IP₃ receptors (IP₃R1). However, precise mechanism of haloperidol action on cardiomyocytes through dopaminergic signaling was not described yet. This study investigated a role of dopamine receptors in haloperidol-induced increase in IP₃R1 and Sig1R, and compared physiological effect of melperone and haloperidol on basic heart parameters in rats.

MATERIALS AND METHODS

We used differentiated NG-108 cells and H9c2 cells. Gene expression, Western blot and immunofluorescence were used to evaluate haloperidol-induced differences; proximity ligation assay (PLA) and immunoprecipitation to determine interactions of D1/D2 receptors. To evaluate cardiac parameters, Wistar albino male rats were used.

KEY FINDINGS

We have shown that antagonism of D2R with either haloperidol or melperone results in upregulation of both, IP₃R1 and Sig1R, which is associated with increased D2R, but reduced D1R expression. Immunofluorescence, immunoprecipitation and PLA support formation of heteromeric D1/D2 complexes in H9c2 cells. Treatment with haloperidol (but not melperone) caused decrease in systolic and diastolic blood pressure and significant increase in heart rate.

SIGNIFICANCE

Because D1R/D2R complexes can engage Gq-like signaling in other experimental systems, these results are consistent with the possibility that disruption of D1R/D2R complex in H9c2 cells might cause a decrease in IP₃R1 activity, which in turn may account for the increase expression of IP₃R and Sig1R. D2R is probably not responsible for changes in cardiac parameters, since melperone did not have any effect.

Should we consider the infusion of lipid emulsion in the resuscitation of poisoned patients?

The use of intravenous lipid emulsions (ILEs) as antidote in local anaesthetic systemic toxicity has gained widespread support following convincing data from animal models, and successful case reports in humans. Proposed beneficial mechanisms of action for ILEs include intravascular sequestration of intoxicant and subsequent enhanced redistribution to biologically inert tissues, augmentation of fatty acid utilisation for ATP synthesis in the context of metabolic poisoning, and direct cardiotonic and ion channel effects. The evidence base for use of ILEs in acute drug intoxication is evolving. The present evidence supports use of ILEs only in local anaesthetic systemic toxicity and in lipophilic cardiotoxin intoxication when there is an immediate threat to life, and other therapies have proven ineffective.

Evaluating the effects and safety of intravenous lipid emulsion on haloperidol-induced neurotoxicity in rabbit

There are many reports on the effect of intravenous lipid emulsion (ILE) as an antidote in drugs related toxicities. We determined the effects of ILE on neurotoxicity of haloperidol (HA), a highly lipophilic antipsychotic, as a model of antipsychotics poisoning. We used six groups of five male rabbits. Two groups received distilled water intravenously followed by infusions of either 18 mL/kg of normal saline or ILE 20%, after 30 minutes. The third group received 18 mL/kg of normal saline after HA (2.6 mg/kg) administration. The three other groups received ILE 20% solution (6, 12, and 18 mL/kg) following HA injection. Catalepsy scores, temperature, pupil size, and mortality rate were measured at 0, 0.5, 1, 2, 3, 4, 8, and 24 hours after HA administration began. Blood and tissue samples were taken from all animals at 24 hours or at death time for biochemical, cell count, and pathological studies. ILE reversed cataleptic scores, miotic pupils, and hypothermia of HA intoxication much faster than normal saline (P < 0.001). Biochemical complications and mortality rate of the animals were significantly higher in the HA + 18 mL/Kg ILE group. ILE reversed sings of HA neurotoxicity; however, synergistic effect of high dose of ILE and HA increased complications and mortality.