Interactions of Aspirin® , i.e. interactions with other drugs, result from the competition for transport proteins in the blood. This applies especially to those drugs which, like Aspirin® , are transported to a target predominantly by binding to such proteins in the blood:Examples include oral antidiabetics (drugs against diabetes mellitus, the most common are the so-called Sulfonylureas (e.g. Euglucon) and Metformin (e.g.
Glucophage) and oral anticoagulants (i.e. drugs to inhibit blood clotting such as Phenprocoumon and Warfarin trade names: Marcumar and Coumadin). If, for example, Aspirin® and Marcumar are taken at the same time, Marcumar is bound to the transport proteins to a lesser extent and the effective levels in the blood increase – without a corresponding dose adjustment, there is a risk of bleeding due to an overdose of Marcumar. The same applies to antidiabetics, which, if taken at the same time as Aspirin®, carry the risk of potentially lethal hypoglycaemia (hypoglycemia). Taking Aspirin® together with glucocorticoids (e.g. cortisone) increases the damaging effect of Aspirin® on the stomach lining.
Aspirin® must not be taken in the last third (trimester) of pregnancy because the prostaglandins formed by cyclooxygenase are needed, among other things, to keep the so-called Ductus Arteriosus Botalli of the unborn child open. Inhibition of the prostaglandin synthesis would lead to its premature closure with fatal consequences for the child. (The Ductus Arteriosus Botalli is a vascular connection between the pulmonary arteries originating from the right ventricle, medically called truncus pulmonalis, and the main artery of the body, the aorta.
This so-called shunt therefore represents a vascular short-circuit: The blood is pumped directly from the right heart into the body’s circulation, bypassing the infant lung, which is not yet required and capable of gas exchange. It is only at birth that the flow is reversed and the Botalli duct closed due to various messenger substances and changes in pressure in the child’s heart. In adults, the rudimentary vascular connection is still preserved as a connective tissue band, medically known as the ligamentum arteriosum): If the Ductus Botalli does not close, inhibitors of the cyclooxygenase are used to suppress the formation of the prostaglandins responsible for the lack of closure.
Another contraindication for Aspirin® is non-specific and psychological pain. If taken regularly, particularly at higher doses, the undesirable side effects predominate and there is a risk of the drug accumulating in cells of the stomach lining, for example. Aspirin® should not be used in children in general, as there is a risk of a rare but very dangerous side effect – Reye’s syndrome (see below). In the case of severe functional disorders of the kidney or liver, the dose must be reduced so that the excretion of Aspirin® after metabolism in the liver takes place predominantly via the kidney. Aspirin® should also not be administered in cases of increased risk of bleeding (the diseases causing this are medically referred to as hemorrhagic diathesis) because of its hemorrhagic effect; examples of such diseases are hemophilia, is based on a defect in blood coagulation factor 8) or von Willebrand syndrome (a genetic defect in von Willebrand factor, which is important for haemostasis and is required for platelets to bind to each other and to close damaged blood vessels)