activity. These tests are conducted in animal models to assess the drug’s potential to cause adverse effects on the cardiovascular system. Early identification of cardiotoxicity helps researchers avoid the progression of unsafe drugs to clinical trials.

Why is Cardiotoxicity Testing Important?

Cardiotoxicity is a significant cause of drug attrition during development. Drugs that affect cardiac function can lead to serious adverse events such as arrhythmias, myocardial infarction, or heart failure. Identifying cardiotoxicity early in the drug development process can help mitigate these risks and improve patient safety, especially for drugs intended for chronic use or targeting cardiovascular diseases.

How is Cardiotoxicity Testing Performed?

Cardiotoxicity testing is typically performed using the following methods:

• Electrocardiogram (ECG) – ECG is used to measure the electrical activity of the heart and assess any abnormalities in heart rhythm, such as prolonged QT intervals, which can indicate arrhythmogenic potential.
• In vivo models – Animal models, such as rodents or larger animals, are used to evaluate heart function, blood pressure, and the overall cardiovascular response to the drug. These models help assess the effects of the drug on cardiac output, heart rate, and vascular function.
• Langendorff heart preparation – This ex vivo model involves isolating the heart and perfusing it with the drug to study the drug’s direct effects on the heart, including contraction and relaxation properties.
• Histopathological examination – Tissue samples from the heart are examined for signs of damage, such as myocardial fibrosis, inflammation, or necrosis, using techniques like H&E staining and immunohistochemistry.

What Are the Key Metrics in Cardiotoxicity Testing?

The key metrics assessed during cardiotoxicity testing include:

• Heart rate and rhythm – Changes in heart rate or the development of arrhythmias are closely monitored to assess potential cardiotoxic effects.
• Blood pressure – Drugs that affect blood pressure, such as causing hypotension or hypertension, may lead to cardiac dysfunction.
• QT interval prolongation – Prolongation of the QT interval on an ECG is a sign of potential arrhythmogenic effects, which can lead to fatal ventricular arrhythmias.
• Histopathology – Structural changes, such as myocyte necrosis or fibrosis, are important indicators of drug-induced damage to the heart muscle.

What Are the Common Applications of Cardiotoxicity Testing?

Cardiotoxicity testing is used to:

• Assess the potential for a drug to cause arrhythmias, myocardial infarction, or other cardiovascular issues.
• Evaluate the long-term effects of a drug on cardiac health, especially for drugs intended for chronic use.
• Identify drugs with potential QT prolongation, which could lead to fatal arrhythmias.
• Screen biologics, small molecules, and new drug candidates for cardiac safety before clinical trials.

How Do the Results of Cardiotoxicity Testing Impact Drug Development?

The results of cardiotoxicity testing help determine whether a drug is safe for clinical trials and eventual use in humans. If significant cardiotoxicity is observed, the drug may be modified or discontinued. For drugs that show promising cardiovascular safety, the results can guide dosing regimens, patient selection, and clinical trial design. The data from preclinical cardiotoxicity testing is critical for regulatory submissions and safety evaluations.

In conclusion, cardiotoxicity testing is a vital part of preclinical drug development. By assessing the effects of drug candidates on heart function, rhythm, and structure, researchers can identify potential risks and ensure that drugs are safe for human use.