ACS and stroke 2 Flashcards

Question

Side effects of prasugrel

Answer 1

Common: anaemia, skin reactions Less common: angioedema

Answer 2

Common: gastrointestinal tract problems, dizziness, headache, gout, skin reactions Less common: confusion, angioedema

Answer 3

- aspirin no longer given for routine primary prevention - anti platelet drugs used mostly for secondary prevention

Answer 4

aspirin or clopidogrel if aspirin not tolerated

Answer 5

aspirin in combination with either ticagrelor, prasugrel or clopidogrel for up to 12 months known as dual antiplatelet therapy (DAPT)- after that, aspirin alone will be continued indefinitely (or clopidogrel if aspirin is not tolerated)

Answer 6

Once it is certain that the patient has suffered an ischaemic event, rather than a haemorrhagic stroke patient is given aspirin during the first 48 hours longer term the patient will be given clopidogrel, or if clopidogrel is unsuitable for them, low dose aspirin can be used instead

Answer 7

drugs in this class exploit one of the regulatory points in the coagulation pathway. there is an endogenous regulator of the cascade called antithrombin III (ATIII), which inhibits the actions of both thrombin and factor Xa drugs that bind to ATIII and increase its affinity for these coagulation factors will therefore block the production of fibrin

Answer 8

Heparin is a natural anticoagulant found in mast cells, though its exact physiological role is unclear. It is a highly negatively charged glycosaminoglycan, made of repeating sugar units with carboxylic acid, sulphate, and amino sulphate groups. Heparin comes in two main forms: unfractioned heparin and low molecular weight heparin LMWH and unfractionated heparin work slightly differently but both act as anticoagulants. negatively charged polysaccharide.

Answer 9

a mix of molecules with varying sizes (3000–30,000 Da)

Answer 10

purified to include smaller molecules, e.g. enoxaparin.

Answer 11

Fondaparinux is a synthetic pentasaccharide based on heparin's structure but much smaller. It works similarly to low molecular weight heparins (LMWHs) but has a better safety profile and longer plasma half-life, making it preferred in some clinical settings

Answer 12

All heparins work by binding to antithrombin III (ATIII), enhancing its ability to inhibit Factor Xa. Unfractionated heparin is large enough to also bind thrombin, so it inhibits both Factor Xa and thrombin. Low molecular weight heparins (e.g., enoxaparin, fondaparinux) are too small to bind thrombin, so they only inhibit Factor Xa through ATIII.

Answer 13

Heparins (unfractionated and low molecular weight) can prolong clotting time and may cause excess bleeding. This is usually reversible by stopping treatment; protamine sulphate can be used as an antidote for serious cases. Both types may cause thrombocytopenia (low platelet count), though it's less common with LMWHs. Heparins aren't absorbed through the gut, so must be injected: Unfractionated heparin is usually given intravenously in hospitals. LMWHs (e.g., enoxaparin, fondaparinux) are given subcutaneously, and patients can be taught to self-administer. Injection site reactions like bruising or pain can occur.

Answer 14

A key drawback of heparin and fondaparinux is that they require injection, making home use less convenient. In contrast, oral anticoagulants are taken as tablets, offering easier administration. There are two main types: Vitamin K antagonists (e.g., warfarin) Direct acting oral anticoagulants (e.g., dabigatran, rivaroxaban)

Answer 15

Warfarin, originally developed as a rat poison, has been used as a therapeutic anticoagulant since the 1950s. It works by inhibiting vitamin K epoxide reductase, an enzyme that recycles vitamin K, which is essential for activating clotting factors II, VII, IX, and X. Without vitamin K recycling, these clotting factors can't be produced, reducing blood clotting. Though commonly called a vitamin K antagonist, warfarin is more accurately a competitive enzyme inhibitor, not a receptor antagonist

Answer 16

Warfarin is a difficult drug to manage due to multiple challenges: It can cause excess bleeding and is teratogenic, risking birth defects or miscarriage, so it should be avoided in women who are or may become pregnant. Warfarin has many drug and dietary interactions: Some drugs inhibit its metabolism, increasing bleeding risk. Others enhance its metabolism, raising the risk of thrombosis. Its metabolism varies significantly between individuals. Warfarin has a delayed onset (up to a week) due to existing stores of vitamin K and clotting factors. Changes in vitamin K intake (from food or gut bacteria) can affect warfarin’s action—antibiotics can reduce vitamin K by killing gut bacteria, thus increasing warfarin's effect.

Answer 17

Patients on warfarin are monitored using the International Normalized Ratio (INR) to track blood clotting speed. Frequent INR tests are done initially, then every 2-4 weeks. If the INR is too high (blood clots too slowly), the dose can be adjusted or reversed with vitamin K or prothrombin in emergencies. Home testing kits are available but not provided by the NHS.

Answer 18

The challenges with warfarin have led to the development of direct-acting oral anticoagulants (DOACs), which offer a safer and easier-to-use alternative. Unlike warfarin, DOACs directly block coagulation factors, avoiding the need for vitamin K depletion.

Answer 19

Dabigatran (brand name Praxada), introduced in 2008, is the first DOAC and became highly successful, earning around $1 billion annually. It directly inhibits thrombin, preventing fibrin formation. Unlike warfarin, dabigatran has fewer drug and dietary interactions, and its more predictable metabolism means it doesn’t require routine INR monitoring. Since 2021, it has been available as a generic

Answer 20

Rivaroxaban (brand name Xarelto), introduced in 2011 by Bayer, is a direct inhibitor of factor Xa, unlike dabigatran, which inhibits thrombin. Like dabigatran, rivaroxaban has fewer drug and dietary interactions and does not require routine INR monitoring.

Answer 21

The most significant side effect of DOACs (dabigatran and rivaroxaban) is excess bleeding, and initially, there were no effective ways to reverse their effects. However, antidotes have now been developed, though they are more expensive than vitamin K for warfarin. Additional side effects include anaemia, gastrointestinal issues, and for rivaroxaban, headache, dizziness, and potential kidney impairment.

Answer 22

DOACs have largely replaced warfarin as first-line treatments, with warfarin as an alternative for some patients. Low molecular weight heparins are also preferred over unfractionated heparin, though older drugs are still used in specific cases.

Answer 23

usually be treated with DOACs but low molecular weight heparins or warfarin may be offered if DOACs are not suitable

Answer 24

Atrial fibrillation (AF) is a common heart rhythm disorder that can lead to thrombus formation, increasing the risk of ischemic stroke. DOACs are the primary treatment for preventing stroke in AF patients, though heparins may also be used in certain cases

Answer 25

Orthopedic surgery for knee or hip replacements carries a high risk of venous thromboembolism, and anticoagulants are used to reduce this risk. Low molecular weight heparins are commonly used, sometimes with aspirin, but DOACs are also frequently employed.

Answer 26

For myocardial infarction, the preferred treatment is percutaneous coronary intervention (angioplasty). During this procedure, intravenous unfractionated heparin is commonly used for antithrombotic therapy due to its short plasma half-life and ease of reversibility

Answer 27

Percutaneous coronary intervention (PCI), or angioplasty, is used to treat blocked coronary arteries, especially after a myocardial infarction. It restores blood flow by inserting a catheter with a balloon and stent to open the blocked vessel. PCI is not first-line for angina but is highly effective after heart attacks, as timely treatment minimizes cardiac muscle damage. The stent, often drug-eluting, prevents plaque regrowth

Answer 28

PCI is the preferred emergency treatment for heart attacks, improving outcomes if done quickly. It is also used for angina not controlled by drugs, reducing angina frequency but not the risk of death or future heart attacks. PCI is not typically used in acute stroke due to difficulty accessing blocked arteries and the common cause being embolism. However, carotid artery stenting can be used after a TIA or mild stroke.

Answer 29

Angioplasty, while minimally invasive, carries risks such as stroke, myocardial infarction, and embolism, where a clot is dislodged and blocks smaller vessels. There is also concern about cognitive decline, although recent studies question this link. Restenosis (re-closing of the artery) can occur in about 30% of patients with bare metal stents, but only around 10% in those with drug-eluting stents.

Answer 30

fibrinolytic and thrombolytic drugs. These are a group of IV medications that exploit the body's own mechanisms for removing blood clots in order to treat thrombosis and embolism.

Answer 31

Thrombolysis accelerates clot breakdown by increasing plasmin production through the use of tissue plasminogen activator (tPA). The main thrombolytic drug used in the UK is alteplase, a recombinant form of human tPA, and reteplase, a modified version with improved stability. Both drugs require intravenous injection, as they cannot be absorbed orally.

Answer 32

Alteplase is commonly used in the treatment of ischemic stroke and heart attacks, especially when PCI is not an option. However, thrombolytic drugs are riskier than PCI for heart attack treatment. They are effective only within a short time window (up to 4.5 hours) after a thromboembolism, as the clot becomes resistant to breakdown beyond that. Thrombolytics are for acute treatment and cannot prevent future heart attacks or strokes.

Answer 33

The primary risk with thrombolytic drugs is increased bleeding and hemorrhage. Therefore, it's crucial to confirm that a stroke is ischemic rather than hemorrhagic before administering thrombolytics, as these drugs can worsen a hemorrhagic stroke, potentially leading to fatal outcomes.