Antipsychotic drugs cause bradycardia in GD 13 rat embryos in vitro

Mapping the Knowledge of Antipsychotics-Induced Sudden Cardiac Death: A Scientometric Analysis in CiteSpace and VOSviewer

The drugs on the market for schizophrenia are first-generation and second-generation antipsychotics. Some of the first-generation drugs have more side effects than the other drugs, so they are gradually no longer being applied clinically. Years of research have shown that the risk of sudden cardiac death in psychotic patients is associated with drug use, and antipsychotic drugs have certain cardiotoxicity and can induce arrhythmias. The mechanism of antipsychotic-induced sudden cardiac death is complicated. Highly cited papers are among the most commonly used indicators for measuring scientific excellence. This article presents a high-level analysis of highly cited papers using Web of Science core collection databases, scientometrics methods, and thematic clusters. Temporal dynamics of focus topics are identified using a collaborative network (author, institution, thematic clusters, and temporal dynamics of focus topics are identified), keyword co-occurrence analysis, co-citation clustering, and keyword evolution. The primary purpose of this study is to discuss the visual results, summarize the research progress, and predict the future research trends by bibliometric methods of CiteSpace and VOSviewer. This study showed that a research hotspot is that the mechanisms of cardiotoxicity, the safety monitoring, and the assessment of the risk-benefit during clinical use of some newer antipsychotics, clozapine and olanzapine. We discussed relevant key articles briefly and provided ideas for future research directions for more researchers to conduct related research.

Cardiac Safety of Clonidine and Quetiapine in Post-Cardiac Surgery Intensive Care Unit Patients

Background: Clonidine and quetiapine are frequently used medications in the cardiac surgery intensive care unit (ICU). Objective: The purpose of this study is to assess the impact of clonidine compared to quetiapine on cardiac safety outcomes in adult cardiac surgery ICU patients. Methods: This was a single-center, retrospective observational analysis at a tertiary care, academic medical center. Results: One hundred and sixty-one cardiac surgery patients who were administered clonidine or quetiapine during their ICU stay were included between June 2015 and May 2017. The major endpoint of this study was a cardiac safety composite of bradycardia, hypotension, and QTc prolongation. Minor endpoints included ICU and hospital length of stay, and in-hospital mortality. There were 115 patients included in the clonidine arm and 46 patients in the quetiapine arm. There was no difference between groups with regard to the major endpoint (30.43% vs 33.15%; P < .8). There was a shorter ICU and hospital length of stay in the clonidine arm compared to quetiapine P < .0001. All other endpoints were not statistically significant. Conclusion: Patients who received clonidine tended to have undergone less complex procedures, be younger, and have a lower APACHE II score than patients who received quetiapine. The incidence of composite cardiac safety outcomes was not different in clonidine compared to quetiapine in cardiac surgery ICU patients.

The effects of nifedipine and ivabradine on the functionality of the early rat embryonic heart. Are these drugs a risk in early human pregnancy?

BACKGROUND

When the human heart begins its earliest contractions from day 21, it lacks a functional autonomic nerve supply. Instead, contractions are generated by regular calcium transients later augmented by the funny current (I_f ) produced by sinoatrial-like cells. This study examined effects of blocking these currents in the early rat embryonic heart.

METHODS

Rat embryos were incubated in vitro with either the calcium channel blocker nifedipine and/or the funny current (I_f ) blocker ivabradine for 1 hr to examine the effects of these drugs on the activity of the embryonic heart.

RESULTS

On gestational day (GD) 10, nifedipine (0.45-1.8 μM) caused asystole at high concentrations (8/10 embryos at 1.8 μM and 3/10 embryos at 0.9 μM) and markedly increased embryonic heart rate (EHR) in all surviving embryos but likely reduced blood flow due to weak contractions. Ivabradine (1.5 μM) caused a 29% reduction in EHR in GD 10 embryos and a greater than 50% reduction in EHR for GD 11-14 embryos. Combined exposure to both nifedipine and ivabradine resulted in an additive effect. The increased EHR due to nifedipine was reduced by the ivabradine.

CONCLUSION

The results suggest that exposure to nifedipine in human pregnancy 3-4 weeks postfertilization may cause a direct effect on the embryonic heart resulting in reduced blood flow leading to abnormal heart and/or blood vessel development and/or embryonic death. Accidental exposure to ivabradine in the organogenic period would be expected to cause embryonic bradycardia, hypoxia, malformations, and embryonic death. This drug is currently contraindicated in pregnancy.

Early Gestational Hypoxia and Adverse Developmental Outcomes

Hypoxia is a normal and essential part of embryonic development. However, this state may leave the embryo vulnerable to damage when oxygen supply is disturbed. Embryofetal response to hypoxia is dependent on duration and depth of hypoxia, as well as developmental stage. Early postimplantation rat embryos were resilient to hypoxia, with many surviving up to 1.5 hr of uterine clamping, while most mid-gestation embryos were dead after 1 hour of clamping. Survivors were small and many had a range of defects, principally terminal transverse limb reduction defects. Similar patterns of malformations occurred when embryonic hypoxia was induced by maternal hypoxia, interruption of uteroplacental flow, or perfusion and embryonic bradycardia. There is good evidence that high altitude pregnancies are associated with smaller babies and increased risk of some malformations, but these results are complicated by increased risk of pre-eclampsia. Early onset pre-eclampsia itself is associated with small for dates and increased risk of atrio-ventricular septal defects. Limb defects have clearly been associated with chorionic villus sampling, cocaine, and misoprostol use. Similar defects are also observed with increased frequency among fetuses who are homozygous for thalassemia. Drugs that block the potassium current, whether as the prime site of action or as a side effect, are highly teratogenic in experimental animals. They induce embryonic bradycardia, hypoxia, hemorrhage, and blisters, leading to transverse limb defects as well as craniofacial and cardiovascular defects. While evidence linking these drugs to birth defects in humans is not compelling, the reason may methodological rather than biological. Birth Defects Research 109:1358-1376, 2017.© 2017 Wiley Periodicals, Inc.

Abnormal pregnancy outcome associated with high-dose maternal tranylcypromine therapy: Case report and literature review

BACKGROUND

Tranylcypromine is a non-selective inhibitor of monamine oxidase which also inhibits the reuptake of norepinephrine. Spontaneous hypertensive reactions to the drug have been reported. In sheep tranylcypromine has been shown to cause a dose-dependent reduction in uterine blood flow. A similar effect in a pregnant woman might induce constriction of the uterine arteries and temporary fetal hypoxia.

CASES

MotherSafe is a state-based Teratogen Information service and currently provides counselling to around 22,000 consumers and healthcare professionals annually regarding exposures during pregnancy and breastfeeding We report on the outcome of 2 pregnancies in a patient treated with high dose tranylcypromine as well as pimozide, diazepam and alprazolam. The first pregnancy resulted in fetal death and autopsy revealed facial dysmorphism with ocular hypertelorism, cardiac defect and placental infarcts. The second pregnancy continued to term but the baby had similar dysmorphic features as well as an atrio-ventricular septal defect and craniosynostosis.

CONCLUSIONS

Due to their unpredictable interactions with many drugs and foods, MAO inhibitors such as tranylcypromine are not commonly used to treat depression and reports of use in pregnancy are rare. We report the outcome of 2 pregnancies with exposure to high doses of tranylcypromine resulting in children with a similar pattern of malformations. The aetiology is unknown but may relate to the vasoactive properties of the drug in above-therapeutic doses.

The teratogenic effect of dofetilide during rat limb development and association with drug-induced bradycardia and hypoxia in the embryo

BACKGROUND

Dofetilide is an antiarrhythmic drug that blocks the cardiac repolarizing current IKr ((IKr, rapid component of the delayed rectifying potassium current). Previous studies have shown that (a) IKr is essential for normal cardiac function of the embryonic heart and (b) dofetilide is teratogenic in rodents. This study was undertaken to examine the mechanism by which dofetilide causes limb defects on gestational day 13 (GD 13) in the rat.

METHODS

Rats were treated with dofetilide (single oral dose, 5 mg/kg) on GD 13 and embryonic heart rates assessed by ultrasound (Vevo770, VisualSonics, Toronto, Ontario, Canada) 2 hr later. Fetuses were examined for malformations on GD 20. In a separate experiment, dofetilide treatment of GD 13 rats was followed 2, 4, 12, or 24 hr with iv dosing with the hypoxia marker, pimonidazole (60 mg/kg). Embryos were collected and heart rates were assessed in vitro and hypoxia in embryo limbs analyzed.

RESULTS

A teratogenic dose of dofetilide at a susceptible stage of development (GD 13) resulted in a period of bradycardia and arrhythmia of the embryonic heart and hypoxia in the developing limbs (GD 13) resulting in limb malformations (GD 20).

CONCLUSIONS

Drugs that induce periods of bradycardia and/or arrhythmia of the embryonic heart and cause the embryo to become hypoxic are potential human teratogens.