Antifibrinolytic drugs and haemostatics

Question 1

What is the mode of action of tranexamic acid?

Answer 1

Inhibits plasminogen activation and thus prevent fibrinolysis

Question 2

What are the indications for the use of tranexamic acid? (6)

Answer 2

1. Local fibrinolysis
2. Menorrhagia
3. Hereditary angioedema
4. Epistaxis
5. General fibrinolysis
6. Prevention and treatment of significant haemorrhage following trauma

*Inhibits plasminogen activation and thus prevent fibrinolysis

Question 3

What is the mode of administration of tranexamic acid?

Answer 3

Oral

Slow IV injection

Question 4

What are the contraindications for the use of tranexamic acid? (3)

Answer 4

1. Fibrinolytic conditions following DIC (unless predominant activation of fibrinolytic system with severe bleeding0
2. History of convulsions
3. Thromboembolic disease

Question 5

Before using tranexamic acid for menorrhagia, what must you exclude?

Answer 5

Structural or histological causes

Fibroids causing distortion of uterine cavity

Question 6

If a patient is taking long-term tranexamic acid for hereditary angioedema, what monitoring needs to be done regularly?

Answer 6

Liver function tests

Question 7

What are the indications of using desmopressin for its haemostatic effect? (3)

Answer 7

1. Mild to moderate haemophilia
   - Intranasal: 300 micrograms every 12 hours
   - IV or S/C: 300 nanograms/kg for 1 dose
2. Mild to moderate von Willebrand’s disease
   - Intranasal: 300 micrograms every 12 hours
   - IV or S/C: 300 nanograms/kg for 1 dose
3. Fibrinolytic response testing
   - Intranasal: 300 micrograms, blood to be sampled after 1 hour for fibrinolytic activity
   - S/C or IV: 300 nanograms/kg

Question 8

What is the route of administration when desmopressin is used for its haemostatic effect?

Answer 8

Intranasal
IV infusion
Subcutaneous injection

Used in mild-to-moderate haemophilia and von Willebrand’s disease, and fibrinolytic response testing

Question 9

Desmopressin is used for its hemostatic effect in the treatment of mild to moderate von Willebrand’s disease, BUT desmopressin is contraindicated in which type of von Willebrand’s disease?

Answer 9

von Willebrand’s disease type IIB

May result in pseudothrombocytopenia

Question 10

What are the contraindications of using desmopressin? (7)

Answer 10

1. Cardiac insufficiency
2. Conditions treated with diuretics
3. History of hyponatraemia
4. Polydipsia in alcohol dependence
5. Psychogenic polydipsia
6. SIADH
7. von Willebrand’s Disease Type IIB (may result in pseudothrombocytopenia)

Question 11

What must you be careful about when prescribing desmopressin to elderly patients? (2)

Answer 11

Increased risk of hyponatraemia and renal impairment

Measure baseline serum sodium concentration, then monitor regularly during treatment; discontinue treatment if levels fall below the normal range. Review treatment if no therapeutic benefit after 3 months.

Question 12

What electrolyte disturbance is a side effect of desmopressin?

Answer 12

Hyponatraemia

Question 13

What are the two adverse effects of desmopressin when taken during pregnancy?

Answer 13

1. Small oxytocic effect in 3rd trimester (stimulates the uterus)
2. Increased risk of pre-eclampsia

Question 14

Why should you avoid prescribing desmopressin to patients on tricyclic antidepressants?

Answer 14

Increased risk of hyponatraemia

TCAs increase secretion of vasopressin

Question 15

Avoid prescribing desmopressin to patients taking drugs that increase secretion of (?)

Answer 15

Vasopressin

Increases risk of hyponatraemia