Cardiotoxicodynamics: Toxicity of Cardiovascular Xenobiotics

A Clinical-Epidemiological Study on Beta-Blocker Poisonings Based on the Type of Drug Overdose

Background

Beta-blockers carry a high risk of potentially causing fatal poisoning if overdosed. We aimed to assess the clinical and epidemiological characteristics of patients with beta-blocker poisoning.

Methods

Patients were categorized based on the type of drug poisoning into propranolol, other beta-blockers, and the combination of beta-blocker groups, respectively. Demographic data, drug toxicity, and clinical, laboratory, and treatment information of different groups were compared.

Results

During the study period, 5086 poisoned patients were hospitalized, of whom 255 (5.1%) had beta-blocker poisoning. Most patients were women (80.8%), married (50.6%), with a history of psychiatric disorders (36.5%), previous suicide attempts (34.6%), and intentional type of exposure (95.3%). The mean ± SD age of the patients was 28.94 ± 11.08 years. Propranolol toxicity was the most common among different beta-blockers (84.4%). There was a significant difference in age, occupation, education level, and history of psychiatric diseases with respect to the type of beta-blocker poisoning (P < 0.05). We observed changes in the consciousness level and need for endotracheal intubation only in the third group (combination of beta-blockers). Only 1 (0.4%) patient had a fatal outcome in toxicity with the combination of beta-blockers.

Conclusion

Beta-blocker poisoning is not common in our poisoning referral center. Propranolol toxicity was most common among different beta-blockers. Although symptoms are not different among defined beta-blocker groups, more severe symptoms are observed in the combination of the beta-blocker group. Only one patient had a fatal outcome in the toxicity with the combination of the beta-blocker group. Therefore, poisoning circumstances have to investigate thoroughly to screen coexposure with combined drugs.

High-Throughput Video Processing of Heart Rate Responses in Multiple Wild-type Embryonic Zebrafish per Imaging Field

Heart rate assays in wild-type zebrafish embryos have been limited to analysis of one embryo per video/imaging field. Here we present for the first time a platform for high-throughput derivation of heart rate from multiple zebrafish (Danio rerio) embryos per imaging field, which is capable of quickly processing thousands of videos and ideal for multi-well platforms with multiple fish/well. This approach relies on use of 2-day post fertilization wild-type embryos, and uses only bright-field imaging, circumventing requirement for anesthesia or restraint, costly software/hardware, or fluorescently-labeled animals. Our original scripts (1) locate the heart and record pixel intensity fluctuations generated by each cardiac cycle using a robust image processing routine, and (2) process intensity data to derive heart rate. To demonstrate assay utility, we exposed embryos to the drugs epinephrine and clonidine, which increased or decreased heart rate, respectively. Exposure to organic extracts of air pollution-derived particulate matter, including diesel or biodiesel exhausts, or wood smoke, all complex environmental mixtures, decreased heart rate to varying degrees. Comparison against an established lower-throughput method indicated robust assay fidelity. As all code and executable files are publicly available, this approach may expedite cardiotoxicity screening of compounds as diverse as small molecule drugs and complex chemical mixtures.

Methylxanthines induce structural and functional alterations of the cardiac system in zebrafish embryos

Background

Zebrafish embryos are emerging as a model for pharmacological and toxicological studies. We used zebrafish embryos to study the general toxicity and cardiovascular effects of eight methylxanthines: aminophylline, caffeine, diprophylline, doxofylline, etophylline, 3-isobutyl-1-methylxanthine (IBMX), pentoxifylline and theophylline.

Methods

Microinjections of the eight methylxanthines were performed in 1-2 cell stage zebrafish embryos and the general toxicity and cardiovascular effects were analyzed at different time points. Embryotoxicity and teratogenicity were evaluated to understand the general toxicity of these compounds. Structural and functional alterations of the heart were evaluated to assess the cardiovascular effects.

Results

Our results showed different activity patterns of the methylxanthines drugs. Caffeine, IBMX, pentoxifylline and theophylline were highly embryotoxic and teratogenic; aminophylline, doxofylline and etophylline were embryotoxic and teratogenic only at higher doses, and diprophylline showed a minimal (<10%) embryotoxicity and teratogenicity. Most of these drugs induced structural alteration of the heart in 20-40% of the injected embryos with the maximum dose. This structural alteration was fatal with the embryos ultimately dying within 120 hpf. All the drugs induced a transient increase in heart rate at 48 hpf which returned to baseline within 96 hpf. This functional effect of methylxanthines showed similarity to the studies done in humans and other vertebrates.

Conclusion

Our results indicate the potential toxicity and teratogenicity of different methylxanthines in the embryos during embryonic development, the most sensitive period of life. Although interspecies differences need to be considered before drawing any conclusion, our study elucidated that a single exposure of methylxanthines at therapeutic range could induce cardiac dysfunction besides causing embryotoxicity and teratogenicity. Of all the drugs, diprophylline appeared to be safer, with lower degree of embryotoxicity, teratogenicity and cardiac toxicity as compared to other methylxanthines.

Electronic supplementary material

The online version of this article (10.1186/s40360-017-0179-9) contains supplementary material, which is available to authorized users.