Stroke drugs

Question 1

Stroke due to blockage

Answer 1

thromboembolic infarction (85%)
- ischaemic stroke
- blood clot stops flow of blood to the area of brain
- cerebral infarction:
> embolism from distant site
> thrombus causing occlusion

Question 2

Stroke due to damage/bleed

Answer 2

intracranial haemorrhage

• haemorrhagic stroke
• blood leaks into the brain
• cerebral, cerebellar, subarachnoid haemorrhage (15%)

Question 3

Stages of development

Answer 3

interruption of blood supply = neurotoxicity = irreversible necrosis, cerebral oedema and inflammation

1. Early hrs = cells get ‘sick’
2. Hours to a day = inflammations cells ‘complete dying process’
3. weeks on = re-routing pathways

Question 4

Antiplatelet Drugs

Answer 4

inhibit platelet aggregation and thrombus formation by preventing GPIIa/IIIb receptor expressionl
Aspirin -
- inhibit COX1, prevents thromboxane formation
- needs to be given in first 24hrs (300mg)
- in TIA given for 2 weeks, then ‘anti-platelet regime’ = aspirin + colpifogrel/dipyridamole
Dipyridamole -
inhibits thromboxane synthase, prevents thromboxane formation
Clopidogrel -
- antagonize actions of ADP at ADP receptors
prevents GPIIa/IIIb receptor interaction:
Abciximab -
- prevents linking of platelets to fibres

Question 5

Thrombolytic drugs

Answer 5

Alteplase (rTPA)- recombinant tissue plasminogen activators
- given i.v in specialist stroke units
- short acting
- must confirm ischaemic stroke before giving by CT/MRI scan
- only effective if given 3/4 hours within ischaemic attack
Streptokinase
Urokinase

Question 6

Anti-coagulant agents

Answer 6

clotting factors are proteins that circulate in the blood
initiated by certain factors that activate Prothrombin to activate fibrinogen to fibrin
fibrin = clot formation, traps platelets

Question 7

Anticoagulant agents - Heparin and Warfarin

Answer 7

activation of anti-thrombin eg Heparin (i.v) activates body’s own anti-clotting molecules, works immediately
inhibition of vitamin K reductase eg. Warfarin
- acts on the liver to inhibit vitamin K reductase as similar in structure to vitamin K
- gradually diminishes concentrations of clotting factors
- eventually body not able to make as much fibrin
- takes days to act
- warfarin in diet can change due to diet, drinking, acute illness, can interact with other drugs

Question 8

Other drugs in treating stroke

Answer 8

Low-molecular weight Heparin eg dalteparin

Thrombin inhibitor eg bivalirudin, lepirudin

Question 9

Long term treatment of ischaemic stroke

Answer 9

1. anti-platelet therapy

2. secondary intervention eg. combined aspirin (75mg) and dipyridamole (200mg x2 daily)

Question 10

Reversing anticoagulation

Answer 10

Vitamin K to reverse warfarin action

urgent = give clotting factors