Introduction:

Paracetamol is among the non-steroidal anti-inflammatory, analgesic and antipyretic drugs most commonly used worldwide. Few studies have focused on clarifying its mechanisms of action on a cardiovascular level.

Objectives:

Evaluate the action of paracetamol on the force of contraction of thoracic aortic rings and on the electrical and contractile activity of isolated perfused Wistar rat hearts.

Methods:

Measurements were taken of the effects of paracetamol on rat aortic rings denuded of their vascular endothelium. Analysis was performed of the actions of the drug on the isolated perfused rat hearts using the Langendorff method. Evaluation was conducted of the amplitude of the force of cardiac contraction and of intervals QT, QTc, QRS and RR of the electrocardiogram. The conditions (control and presence of paracetamol) were compared with a paired samples Student's t-test (p < 0.05) upon verification of the normality of the data.

Results:

Paracetamol had no effects on the vascular smooth muscle of aortic rings or on intervals QT, QTc, QRS and RR of the electrocardiogram at none of the concentrations used. On the other hand, it displayed a statistically significant negative inotropic effect on the isolated hearts dependent on drug concentration. The IC50 estimated for inhibition of the force of cardiac contraction was 17.15 ± 5.33 µmol/L.

Conclusions:

The direct cardiovascular actions of paracetamol are modest, which contributes to a good safety margin for its clinical use in patients without cardiovascular disease.

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