Anti-platelets, Anti-coagulants, and Thrombolytics Practice Flashcards

Vocabulary flashcards covering the mechanisms, indications, side effects, and reversal agents of anti-platelets, anti-coagulants, and thrombolytics based on clinical medicine lecture notes.

Anti-platelets

Medications that inhibit platelet aggregation to prevent clots from forming or getting larger, without breaking down existing clots.

Aspirin

A common anti-platelet medication that inhibits the cyclooxygenase (COX) enzyme, leading to decreased production of prostaglandins and Thromboxane $A2$ ($TXA2$).

Thromboxane $A2$ ($TXA2$)

A molecule released from platelets that signals other platelets to become activated and aggregate.

GP2B3A

A surface protein on platelets that, when active, allows fibrinogen to connect platelets together to form a plug.

P2Y12 Blockers

A class of anti-platelet drugs including Clopidogrel (Plavix), Ticagrelor (Brilinta), and Prasugrel (Effient) that inhibit the action of ADP on platelets.

CYP2C19

A liver enzyme responsible for metabolizing Clopidogrel into its active form; polymorphisms in this enzyme can lead to under-response or hyper-response to the drug.

GP2B3A Inhibitors

Potent anti-platelet medications like Abciximab, Tirofiban, and Eptifibatide that directly block the receptor responsible for platelet-to-platelet connection via fibrinogen.

PDE3 Inhibitors

Drugs like Cilostazol and Dipyridamole that inhibit phosphodiesterase 3, increasing cyclic AMP to hyper-inhibit platelet aggregation and cause vasodilation.

Claudication

Pain in the calf muscles during exertion, such as walking, caused by reduced oxygen supply due to arterial plaques; often treated with Cilostazol.

Anti-coagulants

Medications that inhibit the coagulation cascade to prevent the formation of a fibrin mesh, thereby stopping the secondary hemostatic plug from growing.

Unfractionated Heparin

An intravenous anti-coagulant with a short half-life used for titration; it works by increasing the activity of Anti-thrombin III to inhibit Factor $XA$ and Thrombin ($IIA$).

Low Molecular Weight Heparin (LMWH)

A sub-q injectable heparin (e.g., Enoxaparin) with a longer half-life than unfractionated heparin, typically dosed by weight without routine monitoring.

Warfarin

An oral anti-coagulant that inhibits vitamin K epoxide reductase, preventing the functional synthesis of clotting factors $II, VII, IX, X$ and proteins $C$ and $S$.

INR (International Normalized Ratio)

A standardized parameter used to monitor the effectiveness of Warfarin, particularly reflecting the extrinsic pathway and Factor $VII$ levels.

Direct $10A$ Inhibitors

Oral anti-coagulants (DOACs) such as Apixaban (Eliquis) and Rivaroxaban (Xarelto) that directly inhibit Factor $XA$ without requiring routine monitoring.

Direct Thrombin Inhibitors

Medications that directly inhibit thrombin ($IIA$); includes oral Dabigatran and intravenous agents like Argatroban and Bivalirudin (used as alternatives in HIT).

HIT (Heparin-Induced Thrombocytopenia)

An immune-mediated complication where heparin-PF4 complexes trigger antibody production, leading to platelet activation, consumption (low platelet count), and paradoxically, a high risk of thrombosis.

Thrombolytics

Medications known as "clot busters" (e.g., Alteplase, Tenecteplase) that activate plasminogen into plasmin to actively break down existing fibrin meshes and thrombi.

TPA (Tissue Plasminogen Activator)

An enzyme that catalyzes the conversion of plasminogen to plasmin, leading to the degradation of fibrin and fibrinogen into degradation products like D-dimer.

Reye's Syndrome

A potentially fatal condition caused by giving aspirin to children with viral infections, characterized by mitochondrial damage, liver failure, hyperammonemia, and encephalopathy.

TTP (Thrombotic Thrombocytopenic Purpura)

A rare condition that can be induced by the older drug Ticlopidine, characterized by the pentad of fever, anemia, thrombocytopenia, renal failure, and neurological symptoms.

Warfarin-induced Skin Necrosis

A condition occurring in the first $3$ to $5$ days of Warfarin therapy where a transient hypercoagulable state (due to rapid drops in Protein $C$) causes thrombosis and necrosis of cutaneous vessels.

Protamine Sulfate

The specific reversal agent used for Heparin-induced bleeding.

Idarucizumab

A specific monoclonal antibody used as a reversal agent for the direct thrombin inhibitor Dabigatran.

PCC (Prothrombin Complex Concentrate)

A treatment used alongside Vitamin $K$ to rapidly reverse Warfarin by replenishing factors $II, VII, IX, and X$.

TXA (Tranexamic Acid)

An antifibrinolytic medication used to help reverse the effects of thrombolytics by inhibiting the breakdown of fibrin clots.