(8.1) Anti-thrombotics Flashcards
In general, what types of drugs do you give to patients with:
- arterial diseases?
- venous diseases?
- Arterial (e.g. MI, CVS accidents): Anti-platelets, Thrombolytics
- Venous (e.g. DVT, PE): Anti-coagulants
What is the mechanism of action of Aspirin?
Irreversibly cause acetylation of COX enzymes -> -Prostaglandin:
- > Anti-inflammatory
- > -Thromboxane A -> -Platelet aggregation
Suggest 4 ADRs of Aspirin.
- Dyspeptic (ulcers/heartburns)
- Renal failure (reduced GFR)
- Bleeding, bruising
- Allergy
What is the mechanism of action of Warfarin?
Inhibits Vitamin K into active form -> reduce production of Factor VII, IX, X
A 74-year old man needs total hip replacement. He is on Warfarin. What do you need to do prior to the surgery and why?
Replace his Warfarin with Low Molecular Weight Heparin, because Warfarin has slow offset, use Heparin to prevent haemorrhage during the surgery.
A 62-year old woman is diagnosed with Deep Vein Thrombosis, how would you manage her medications?
- Warfarin (but slow onset)
- Low molecular weight Heparin as loading dose
Suggest 4 factors/drugs that may increase the INR of a patient?
INR = International Normalised Ratio (the higher the ratio, the stronger the effect of Warfarin)
- CYP450 enzyme inhibitors: Omeprazole, Disulfram, Ethanol, Valporic Acid, Isoniazid, Cimetidine, Erythromycin, Sulphonamide
- Anti-platelet: Aspirin
- Substances decrease Vit K: Cephalosporin (kills GI flora)
- Protein displacements: NSAIDs
Suggest two measurements to monitor the effectiveness of Warfarin.
- Prothrombin tests
- International Normalised Ratio
Suggest 4 indications of Warfarin
- Deep Vein Thrombosis
- Pulmonary Embolism
- Atrial Fibrillation
- Prosthetic valves
Suggest a non-vascular ADR of Warfarin.
Teratogenic
A patient who was discharged after his DVT is treated and given medications. He comes back to the outpatient clinic complaining of increased and easy bruising. His INR is found to be >10. What may have happened and what options are available to you to treat his situation?
- Too much Warfarin
- Give Vitamin K to reverse Warfarin’s action
What is the mechanism of action of Heparin?
Inhibit Anti-thrombin III -> reduced production of Factor X
What are the routes of administration of:
- Low molecular weight Heparin?
- Unfractionated Heparin?
- LMWH: Subcutaneous
- UFH: IV
(low oral bioavailability)
Which type of Heparin is more preferred to use and why?
- Low molecular weight heparin is preferred
- Unfractionated heparin has more ADRs and less predictable, hence needs monitoring (Activated Partial Thromboplastin Time Test)
Suggest 6 indications of Heparin
Preventives: - Pre-surgical - Low mobility Treatments: - Deep Vein Thrombosis - Pulmonary Embolism - Atrial Fibrillation - Acute Coronary Syndrome (Unstable Angina, MI, Coronary Artery Thrombosis)
