Hemostasis and Thrombosis Drugs

Question 1

The four steps of hemoSTATUS

Answer 1

Localized vasoconstriction
Primary hemostasis
-Platelet adhesion and activation
-Primary hemostatic plug
Secondary hemostasis  (Coagulation cascade)
Activation of Thrombin
-Permanent plug
-Anti-thrombin mechanisms

Question 2

Anti-coagulants

Answer 2

Affect Platelets
-Aspirin
-Plavix
-Persantine
Affect Clotting Cascade
-Coumadin
-Heparin
-Lovenox
-Pradaxa

Question 3

Platelet activation

Answer 3

Thromboxane A
ADP
Thrombin

Question 4

Aspirin

Answer 4

Class: Anti-Coagulants; Affect Platelets

Mechanism of action:

• ASA inhibits COX irreversibly
• Prostaglandins: precursor of thromboxane A2 (TA2)
• TA2: potent inducer of platelet aggregation
• Platelets do not contain a nucleus
• Platelets: No TA2; 10 day lifetime

Indication:

• Prevention of arterial thrombosis: Stroke, MI, Transient ischemic attack
• Low doses and infrequent intervals: 81 mg po every day
• Higher doses (325 mg) for anticoagulation therapy

Pharmacological effects:

How this drug might effect dental treatment of patient
oAdverse effects you have to consider:

oContraindicated drugs:

oContraindications:

oWhich analgesic can the patient take:

Question 5

Clopidogrel (Plavix)

Answer 5

Class: Anti-Coagulants; Affect Platelets

Mechanism of action:
-Irreversibly inhibits platelet aggregation
Covalently modify the P2Y12 ADP receptor
-Inhibits sustained aggregation: Transient can still occur
-Inhibition last the lifetime of the platelet
-Need to discuss dental surgery with physician

Indication:

• Secondary prevention: MI, Stroke, Peripheral vascular disease
• Coronary artery stents
• Coronary artery bypass grafting

Pharmacological effects:

Recommendations:

• Elective procedures should be deferred until the patient has completed an appropriate course of Plavix therapy
• 12 months after DES (drug eluting stents) implantation
• 1 month for bare-metal stent implantation

How this drug might effect dental treatment of patient
oAdverse effects you have to consider:

oContraindicated drugs:

oContraindications:

oWhich analgesic can the patient take:

Question 6

Dipyridamole (Persantine)

Answer 6

Class: Anti-Coagulants; Affect Platelets

Mechanism of action:

• Phosphodiesterase and platelets
• Increase in cAMP levels in platelets leads to a decrease in adhesion
• Inhibitors of phosphodiesterase decrease platelet aggregation by inhibiting cAMP degradation

Indication:

• With warfarin in prosthetic heart valve replacement
• With ASA to reduce stroke risk

Pharmacological effects:

How this drug might effect dental treatment of patient
oAdverse effects you have to consider:
-Causes gingival bleeding

oContraindicated drugs:

oContraindications:

oWhich analgesic can the patient take:

Question 7

Mechanism of action of antiplatelet agents

Answer 7

• Aspirin inhibits TA2 formation.
• Plavix binds irreversibility to the P2Y (ADP) receptor.
• Dipyridamole inhibits PDE, increasing cAMP concentrations

Question 8

Coumadin

Answer 8

Class: anti-coagulant

Mechanism of action: inhibit vitamin K epoxide reductase (vit K is cofactor for synthesis of many coagulation factors)

Indication:

Pharmacological effects: t1/2 of 40hrs duration of 2-5 days

How this drug might effect dental treatment of patient: INR every 2 weeks, watch for vit K in diet
oAdverse effects you have to consider: too much bleeding, too little: angina, blood clots

oContraindicated drugs:aspirin, ibuprofen, tetracyclines, several anti-fungals

oContraindications:

oWhich analgesic can the patient take:

Question 9

Enoxaparin (Lovenox)

Answer 9

Class: Low molecular weight heparins

Mechanism of action:

• induces conformational change in antithrombin III
• inactivates factor Xa

Indication: used as a “bridge to warfarin”

Pharmacological effects:

• longer t1/2 than heparin
• sub q injection

How this drug might effect dental treatment of patient
oAdverse effects you have to consider:

oContraindicated drugs:

oContraindications:

oWhich analgesic can the patient take:

Question 10

Pradaxa (Dabigatran)

Answer 10

Class: Direct Thrombin Inhibitor

Mechanism of action:

Indication: Reduce risk for stroke in pts with atrial fibrillation

Pharmacological effects: No antidote to reverse activity

How this drug might effect dental treatment of patient
oAdverse effects you have to consider:

oContraindicated drugs:

oContraindications:

oWhich analgesic can the patient take: