Anticlotting drugs Flashcards
What are 4 classes of anti-platelet drugs?
1) NSAIDs
2) Platelet Gp2b/3A receptor blockers
3) ADP receptor blockers
4) PDE inhibitors
What is the anti-clotting moa of aspirin?
Non-selective COX inhibitor → inhibit TXA2 → inhibit platelet aggregation
What 3 clinical uses of aspirin as an anti-clotting drug?
1) Transient cerebral ischaemia prophylaxis
2) ↓incidence of recurrent MI
3) ↓mortality of post-MI px
What are 2 AEs of aspirin?
Bleeding (↓PGI2)
Gastric upset and ulcers (↓PGE2)
What are 2 examples of ADP receptor blockers?
Reversible:
Clopidogrel and Ticlopidine
Irreversible (faster onset):
Ticagrelor
What is an example of PDE inhibitor?
Dipyridamole
What are 3 examples of Gp2b/3A receptor blockers?
1) Abciximab (humanised mAb)
2) Eptifibatide (analogue of fibrinogen receptor-binding region)
3) Tirofiban (small molecule blocker)
What are 4 anti-coagulant classes?
1) Heparin derivatives
2) Coumarin derivatives (Warfarin)
3) Lipirudin/Hirudin
4) Anti-thrombin 3
LMW heparin have (better/worse) bioavailability and (longer/shorter) T1/2 compared to unfractionated heparin.
Better F
Longer T1/2
What is the moa of heparin?
Bind to Anti-thrombin 3 → conformational change → allows for binding to F2a (only unfractionated) and FXa
True or false: LMWH increases antithrombin 3’s action on both F10a and F2a.
False.
LMWH only increases for F10a not F2a (thrombin)
What are 3 clinical indications of heparin?
1) DVT, PE, AMI
2) Revascularisation (w thrombolytics)
3) Angioplasty/coronary stents (w GP2b/3a inhibitors)
4) When anticoagulation must be used in pregnancy
How is heparin administered?
IV or subcut
cannot IM → haematomas
What are 2 AEs of heparin?
1) Haemorrhage
2) Thrombocytopenia
3) HS to heparins/pork products
Caution:
4) Elderly patients
5) Risk of bleeding
What are 4 DDIs/FDis of Heparin?
DDIs:
1) Antiplatelet
2) Anticoagulation
3) Fibrinolytics
4) NSAIDs
5) SSRIs
FDIs:
6) Chamomile
7) Fenugreek
8) Garlic
9) Ginger
10) Gingko
11) Ginseng
How are haemorrhages due to heparin treated?
1) Stop heparin therapy
2) Protamine sulfate (cationic peptide → sequester heparin)
3) Vitamin K
(Heparin/warfarin) can be given during pregnancy.
Heparin
How is warfarin administered?
Orally
What is the moa of Warfarin?
Vitamin K reductase inhibitor (Vitamin K antagonist)
→ ↓reactivation of oxidised vitamin K to reduced form
→ ↓carboxylation/functional activation of coagulation factors 2, 7, 9, 10
What are 3 AEs of warfarin?
1) Haemorrhage/bleeding
2) Hepatitis
3) Cutaneous necrosis
When is warfarin contraindicated?
1) HS to drug
2) Active bleeding/bleeding risk
3) Severe or malignant HTN
4) Severe renal hepatic disease
5) Subacute bacterial endocarditis, pericarditis, pericardial effusion
6) Pregnancy
Caution in:
1) Breast-feeding
2) Diverticulitis, Colitis
3) Mild/moderate hypertension
4) Mild/moderate renal/hepatic disease
5) Drainage tubes in any orifice
What is used to titrate the dose of warfarin?
1) INR
2) PT
Why are DDIs of concern when administering warfarin?
Warfarin is metabolised by CYP450
What are 4 DDIs/FDIs that ↑bleeding risk in patients on Warfarin?
Drugs:
1) Paracetamol
- Long term, high dose (>2g/day, >2 weeks)
2) Allopurinol
3) NSAIDs
4) Salicylates
5) PPIs
6) Metronidazole
Food:
7) Cranberry juice
8) Reishi mushrooms
9) Gingko
10) Ginseng
