care, administer treatments, and monitor the health of the animals during the study.

Laboratory Technicians: Prepare test substances, administer doses, collect blood and tissue samples, and perform tests such as ECG and histopathological analysis.

Quality Assurance (QA): Ensure adherence to internal SOPs, GLP standards, and regulatory guidelines, and perform audits to verify the integrity and accuracy of the data.

4) Procedure

The following steps outline the procedure for performing cardiotoxicity testing using preclinical models:

1. Step 1: Study Design
   1. Define the study objectives, including the specific cardiovascular endpoints to be evaluated (e.g., arrhythmias, changes in heart rate, blood pressure, cardiac histopathology).
   2. Select the appropriate animal model (typically rodents such as rats or mice) based on the study design and species suitability for cardiovascular testing.
   3. Determine the doses of the test substance, the administration route (e.g., oral, intravenous), and the dosing schedule. Ensure that the study includes dose levels that are expected to produce therapeutic, sub-therapeutic, and toxic effects.
   4. Establish control and treatment groups, including positive and negative controls to assess cardiovascular function.
2. Step 2: Animal Preparation
   1. Ensure that animals are acclimatized to the testing environment before the start of the study, as environmental stress can affect cardiovascular parameters.
   2. Ensure proper health screening for animals to be used in the study, and that they meet the study’s inclusion criteria for weight, health, and age.
   3. Randomly assign animals to the treatment and control groups, ensuring that the number of animals per group is statistically sufficient to detect meaningful differences.
3. Step 3: Treatment Administration
   1. Administer the test substance to the treatment group according to the study protocol. Control groups should receive the vehicle or no treatment as required.
   2. Ensure that the drugs are administered accurately, and that doses are correctly calculated based on animal weight and the study design.
   3. Monitor animals closely for signs of distress or adverse reactions after drug administration, including cardiovascular changes like changes in heart rate, breathing, or signs of arrhythmias.
4. Step 4: Cardiovascular Monitoring
   1. Measure heart rate and blood pressure at predefined time points using non-invasive (e.g., tail-cuff) or invasive (e.g., telemetry, catheterization) methods, depending on the study design.
   2. Perform continuous ECG monitoring to assess for arrhythmias and other cardiac abnormalities. Record any significant changes in ECG parameters such as PR interval, QRS complex, QT interval, and heart rate variability.
   3. Ensure that data is collected at multiple time points to evaluate both acute and chronic effects of the test substance on cardiovascular function.
5. Step 5: Tissue Collection and Histopathology
   1. At the end of the study, euthanize the animals and collect heart tissue samples for histopathological examination to evaluate potential damage caused by the drug.
   2. Fix heart tissue in formalin, and prepare tissue sections for staining (e.g., H&E staining) to assess the presence of lesions such as myocardial necrosis, fibrosis, or inflammation.
6. Step 6: Data Analysis
   1. Analyze the data to evaluate the effects of the test substance on cardiovascular parameters such as heart rate, blood pressure, and ECG readings.
   2. Statistically analyze the differences between the control and treatment groups using appropriate tests (e.g., t-test, ANOVA) to determine the significance of the observed effects.
   3. Interpret the data to determine whether the drug induces arrhythmias, changes in blood pressure, or other cardiovascular abnormalities that may indicate cardiotoxicity.
7. Step 7: Reporting and Documentation
   1. Prepare a detailed report summarizing the study objectives, methodology, results, and conclusions regarding the cardiovascular effects of the drug.
   2. Include data on heart rate, blood pressure, ECG changes, histopathological findings, and statistical analysis of these data in the report.
   3. Document any deviations from the study protocol, including the reasons for changes and any unexpected findings during the study.
   4. Store all raw data, analysis logs, and final reports securely for future reference and regulatory audits.
8. Step 8: Sample Disposal
   1. Dispose of all used biological samples, test substances, and laboratory waste according to biosafety and waste disposal regulations.
   2. Ensure proper disposal of hazardous materials in designated biohazard containers to prevent contamination and ensure compliance with safety standards.

5) Documents

The following documents should be maintained during the cardiotoxicity testing process:

1. Study Protocols
2. Animal Treatment and Monitoring Logs
3. Cardiovascular Measurement Data (e.g., ECG, heart rate, blood pressure)
4. Histopathology Reports
5. Cardiotoxicity Study Reports
6. Raw Data and Statistical Analysis Logs
7. Waste Disposal Records

6) Abbreviations

• GLP: Good Laboratory Practices
• ECG: Electrocardiogram
• FDA: Food and Drug Administration
• QA: Quality Assurance

7) References

References to regulatory guidelines and scientific literature that support this SOP:

• OECD Principles of Good Laboratory Practice (GLP)
• FDA Guidelines for Cardiotoxicity Testing
• ICH Guidelines for Nonclinical Safety Testing

8) Version

Version 1.0: Initial version of the SOP.

9) Annexure

Cardiotoxicity Study Report Template

Parameter	Units	Control Group Value	Treatment Group Value	Statistical Significance (p-value)
Heart Rate	bpm
Blood Pressure	mmHg
QT Interval (ECG)	ms
Histopathological Findings	Lesion Type