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Flashcards in Haem Drugs Deck (16):

MOA of Aspirin

What is the goal?

When is it contraindicated?

Irreversibly acetylates COX-1 and inhibits COX-2 less strongly.
Inhibiting COX-1 prevents formation of thromboxane A2 which is needed for platelet activation, so platelet activation is hence inhibited for 7-10 days (platelet lifespan)
Produces prostaglandins- reduces adhesion

Preventing coagulation. NOT for asthmatics or renal disease


What is Dipyridamole?
How does it works and when is it used?

Relatively weak effect. Inhibits platelet phosphodiesterase and prevents cAMP breakdown, reducing intracellular Ca and inhibiting platelet activation.

Preventing clots. Usually given alongside aspirin as Asasantin SR


Name the ADP receptor antagonists

What is the MOA?

Ticlopidine, clopidogrel, prasugrel and ticagrelor

ADP receptor antagonists

Prodrugs (metabolised by hepatic cytochrome P450) that selectively inhibit ADP-induced platelet aggregation by irreversibly blocking P2Y12.


Name the GPIIb/IIIa receptor antagonists

What is the MOA?
When are they used?

Tirofiban, eptifibatide and abciximab

Block the glycoprotein IIb/IIIa receptor on platelet surface, preventing them from binding to ligands that let platelets aggregate

Usually used in combination with other anti-platelets to prevent coagulation.


How does Heparin work?

Activates antithrombin and increases its inhibitory rate 1000-fold, Neutralising thrombin and activated factor X (as well as IX, XI, XI, XII, also prevents I to Ia)
Must bind to both antithrombin and thrombin simultaneously .Binding to heparin causes a conformational change in antithrombin which also accelerates its interaction with factor Xa.

Preventing coagulation by halting the clotting cascade.


Name the Xa inhibitors and explain how they work

Inhibit factor Xa which is the active enzyme in the prothrombinase complex, inhibiting the coagulation cascade.

Low molecular weight heparin (Clexane), fondaparinux, rivaroxaban and apixaban


Warfarin MOA

Interferes with the synthesis of Vitamin K-dependent proteins (by blocking vitamin K epoxide reductase) (VKOR) including prothrombin and factors VI, IX and X. It also reduces levels of proteins C and S.

Preventing coagulation by halting the clotting cascade.
Also stabilises current clots due to inhibition of Protein C


Used for?

Convert plasminogen to plasmin, which degrades the fibrin matrix of thrombi and dissolves clots. tPAs are "clot-specific" because they preferentially activate fibrin-bound plasminogen.

Used for Fibrinolysis

Examples: Tenecteplase, alteplase and reteplase


Hydroxyurea MOA

Blocks conversion of the cytosine nucleotide to the deoxy derivative and further inhibits DNA synthesis through blocking incorporation of the thymidine nucleotide to DNA

Used for : Chemotherapy and sickle cell anaemia and CML


What is Prothrombinx and what factors does it include?
When is it used?

Sterile freeze dried powder containing purified human coagulation factors II, IX, X and low levels of V and VII

Used as a coagulation replacement when vitamin K deficient


What is Desmopressin
When is it used?

Releases VWF from platelet granules therefore increases circulating Factor VIII

Used for :

Factor VIII deficiencies- bleeding in Haemophilia A


MOA of Tranexamic acid
When is it used?

Class: Antifibrinolytic

MOA: Inhibits plasminogen activation and thus preventing fibrinolysis

USed for :
Bleeding or risk of bleeding- ie haemorrhage following dental procedure or Menorrhagia
Or bleeding after thrombolytic drug administration


What are some TKI? What is the MOA and When are they used?

Imatinib, Nilotinib, Dasatinib

Inhibitor of TK to reduce uncontrolled growth and proliferation

Used in CML


MOA of Methotrexate

Inhibits folic acid reductase so folic acid can’t be converted to tetrahydrofolic acid, blocking purine synthesis ∴ no DNA production


MOA of 5-Fluorouracil

What are the examples?

Acts as an antimetabolite and prevents synthesis of the thymidine nucleotide, blocking DNA production

Common names:

Gemcitabine and arabinosylcytosine act in similar ways.


MOA of Doxorubicin

Inhibits DNA and RNA synthesis- interferes with topoisomerase II which is needed to stabilise DNA strands when unwinding

Chemotherapy- haematological and solid cancers