Thrombolytics are drugs that dissolve clots in the blood. These clots can block arteries, preventing oxygen from getting to tissues in the body and causing damage. The drugs are commonly used as emergency treatment in conditions such as heart attack and stroke. Thrombolytics cannot, however, be used in every circumstance. Contraindications for thrombolytics, or situations where the use of these drugs is not advisable, can be either absolute or relative.
Absolute contraindications mean that the drugs should not be administered to the patient. The risk of the patient taking these drugs outweighs any positive effect that the drugs might have. Absolute contraindications for thrombolytics include if the patient has active internal bleeding or a suspected aortic dissection. As the patient in these situations is already bleeding heavily, or has the potential to bleed, medications that prevent blood from clotting could be life threatening.
Other situations where the drugs should be avoided include if the patient has undergone traumatic cardiopulmonary resuscitation or has had an intercranial condition, such as injury, tumor, or aneurysm, in the previous six months. The extent of the damage in these conditions is often not known for a number of months, and thrombolytic drugs could result in internal bleeding. Thrombolytic drugs should also not be given to patients who have severe hypertension, are pregnant, or have undergone major surgery in the previous two weeks. Finally, under no circumstances should the drugs be given to patients who have had a previous allergic reaction.
Relative contraindications for thrombolytics include situations where giving the drug to the patient can have significant risk, but this risk can be outweighed by the potential benefit. Doctors decide these situations on an individual basis. Relative contraindications for thrombolytics include if the patient has a known bleeding disorder such as hemophilia or is currently using anticoagulant medications, such as warfarin, which reduce the ability of the blood to clot. Patients with peptic ulcer disease, renal disease, or diabetic retinopathy are also contraindicated for thrombolytics due to bleeding complications; however, these risks may be outweighed by the need for the drug.
Other relative contraindications for thrombolytics include a recent trauma to the patient or a major surgery performed in the previous two months. Patients whose blood pressure was very high but is currently controlled may also be considered candidates for the drugs if they are otherwise in good health. Finally, patients who have suffered cerebrovascular accidents in the past can be given the drugs but must be closely supervised to make sure there are no ill effects.