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In this lesson, we'll go over the use of fibrinolytic medications and all of their effects, including indications, precautions and contraindications, and adult dosages.
Fibrinolytic medications are not usually found in advanced cardiac life support pharmacological drug cards specifically. However, their use is vitally important to reperfusion therapies.
Fibrinolytic drugs – also called thrombolytic drugs – are any medication that is capable of stimulating the dissolution of blood clots, or as they're sometimes referred to as – thrombus. These types of drugs work by activating something referred to as fibrinolytic pathways.
Pro Tip #1: This is important because it differentiates fibrinolytic medications from anticoagulant drugs, routinely referred to as heparin and Coumadin – Two common anticoagulants that work by preventing normal clotting factors from functioning correctly, thereby inhibiting the blood from clotting.
Fibrinolytic medications, which prevent the formation of blood clots by suppressing the function of multiple clotting factors that are normal and present in the blood, are different from anticoagulants.
Pro Tip #2: There are numerous fibrinolytic agents on the market, each of which may produce varying mechanisms of action. And while there are similarities between these are anticoagulants, fibrinolytic drugs produce the therapeutic effect of breaking down the fibrin and fibrinogen matrix of a thrombosis (fibrinolysis), thus fragmenting the clot that is obstructing an artery and reestablishing distal blood flow.
Fibrinolytic Indications
Now let's take a look at some indications for fibrinolytic medications.
The most common indication for the use of fibrinolytic medications include the following two:
- Acute myocardial infarction, also known as AMI.
- Acute ischemic stroke, also known as AIS.
In patients with acute myocardial infarction, fibrinolytic drugs would be indicated if the ST-segment elevation is consistent with a myocardial infarction of greater than or equal to 1mm in two or more contiguous leads. Contiguous leads are next to one another anatomically speaking. They view the same general area of the heart (specifically the left ventricle).
Fibrinolytic drugs can also be indicated if the signs and symptoms of a myocardial infarction last longer than 15 minutes and less than 12 hours and if PCI (percutaneous coronary intervention) is not available within 90 minutes of medical contact.
If the indication is related to ischemic stroke, patients may qualify if they suffer from sudden onset of a focal neurological deficit such as:
- Slurred speech
- Facial droop
- Weakness on one side of their body
- Paralysis on one side of their body
Patients may also qualify for fibrinolytic medications if the stroke symptoms do not seem to be self-resolving, which is what you usually see when it's a transient ischemic attack (or TIA) and the signs and symptoms are present for up to three hours but not greater than 4.5 hours.
Fibrinolytic Precautions and Contraindications
There are a few precautions and contraindications when it comes to administering fibrinolytic medications that you should be aware of.
When using fibrinolytic drugs, there are several patient factors that would exclude their use, which include (but are not limited to):
- Hypertension with systolic blood pressure greater than 180 to 200mm HG
- Right arm vs. left arm blood pressure differences greater than 15mm HG
- Significant head or facial trauma within the past 3 months
- Prior intracranial hemorrhage
- A bleeding disorder or internal bleeding within the prior 2 to 4 weeks
- The use of a current anticoagulant treatment
- Pregnancy
- A serious systemic disease which would include advanced cancer or kidney disease
- Ischemic stroke greater than 3 hours or less than 3 months
Pro Tip #3: However, that last contraindication would not include the current condition being considered for the current fibrinolytic treatment.
Adult Dosage of Fibrinolytic Medications
The adult dosage for fibrinolytic treatments can be a little complex because the dose of the treatment would depend on the exact fibrinolytic medication being used.
Having said that, there are three major classes of fibrinolytic drugs: tissue plasminogen activator (tPA), streptokinase (SK), and urokinase (UK). While drugs in these three classes all have the ability to effectively dissolve blood clots, they differ in their detailed mechanisms in ways that alter their selectivity for fibrin clots.
