Haematological Drugs Flashcards
(42 cards)
What is an example of an anti-platelet drug?
- Acetylsalicylic Acid (Aspirin)
* Clopidogrel
What is the mechanism of action for aspirin?
- irreversible inactivation of cyclooxygenase (COX) enzyme
- this reduces platelet thromboxane (TXA2) production and endothelial prostaglandin (PGI2) production.
- reduced platelet thromboxane production reduces platelet aggregation and thrombus formation
- reduced prostaglandin synthesis decreases nociceptive sensitisation and inflammation.
What is the main indication (use) of aspirin?
- secondary prevention of thrombotic events
* pain relief
List some side effects of aspirin
- bleeding
- peptic ulceration
- angioedema
- bronchospasm
- Reye’s syndrome (rare)
What information should you tell the patient before starting Aspirin?
- avoid over the counter preparations that contain aspirin
* some patients advised to take a PPI alongside long-term aspirin
What drug class is clopidogrel?
an anti-platelet drug
What is the mechanism of action for Clopidogrel?
- irreversibly blocks the ADP-receptor on platelet cell membranes
- consequently inhibits formation of GPIIb/IIIa complex, required for platelet aggregation
- decreased thrombus formation
What is the main indication of clopidogrel?
secondary prevention of thrombotic events
What are the side effects of clopidogrel?
- bleeding
* abdominal pain/diarrhoea
What is important clinically regarding Pharmacokinetics/dynamics for clopidogrel?
Avoid in liver failure
What information should you tell the patient before starting Clopidogrel?
- advise to stop before surgical procedures
* patients shouldn’t stop it without consulting doctor if they have an arterial stent in-situ
What class of drugs are Tenecteplase and Alteplase?
Recombinant Tissue Plasminogen Activator (rtPA)
What is the mechanism of action of rtPAs?
- recombinant form of tissue plasminogen activator
- catalyses conversion of plasminogen to plasmin
- promotes fibrin clot lysis
What are the indications of Recombinant Tissue Plasminogen Activators?
- acute ischaemic stroke within 4.5hrs of onset
- MI within 12hrs of onset
- massive PE
List the side effects of Tenecteplase and Alteplase
- bleeding
* allergic reaction/angioedema
What are important pharmacokinetic/dynamic features to note clinically regarding rtPAs?
- bolus-infusion regimen is used for Alteplase
- Tenecteplase is given as a single bolus
- PD interactions with other blood thinners
What info should you tell the patient before starting Tenecteplase or Alteplase?
When using thrombolytic drugs, patients should be aware of risk:benefit ratio, which should include reference to rate of bleeding complications
What is are examples of a Heparin drug?
Unfractionated Heparin;
LMW Heparin
What is the mechanism of action of heparins?
- enhances activity of antithrombin III
- antithrombin III inhibits thrombin
- heparins also inhibits multiple other factors of the coagulation cascade
- this produces its anticoagulant effect
What are the indications of heparins?
- treatment and prophylaxis of thromboembolic diseases, including induction of vitamin K antagonists.
- renal dialysis
- acute coronary syndrome treatment
what are the side effects of heparin?
- bleeding (major haemorrhage risk can be as 3.5%
- heparin-induced thrombocytopenia
- osteoporosis
(LMW heparins have less risk)
what are important pharmacokinetic/dynamic features to note clinically regarding unfractionated heparins?
- administered by continuous IV infusion or subcut injection
- complex kinetics - non-linear relationship between dose/ 1/2 life and effect - needs TDM
- effect monitored using activated PTT
- anticoagulant effect reversed by protamine
- unfractionated heparin has a shorter duration than LMW Heparin
- used in preference to LMW heparin, in selected patients, due to the shorter duration of action and reversability with protamine
What information should be given to patients before starting heparin?
- risk of bleeding
- regular blood monitoring required
- (for LMW heparin) - will need blood testing prolonged therapy
what are important pharmacokinetic/dynamic features to note clinically regarding LMW heparins?
- subcut injection
- more predictable dose-response relationship than unfractionated
- 2-4 times longer plasma half-life than unfractionated
- clearance is mostly renal, therefore longer 1/2 life if have renal failure
- less readily reversed with protamine than unfractionated heparin
