anti-coagulants

1. Pharmacology
Slide-33
Anti-coagulants

2. Anti-coagulants
 Drugs interfere with the clotting and are used
to prevent and treat venous thrombosis.
 Anti coagulants include:
1.Heparin and it derivatives.
2.Coumarins : Warfarin and phenindione.

3. Heparin
 Is a complex mixture of acid substances.
*inhibit coagulation by binding to antithrombin
III. This binding enhance the action of
antithrombin’s to enhance other clotting factors.
*the net result is prolongation of clotting time.
Clotting time : is the time needed for blood or
plasma to coagulate under controlled lab
conditions.

4. Heparin
Two preperations of heparin:
1.Unfractionated heparin
2.Low molecular weight heparin
 Heparin is a large molecule, it can be breaking
down into a number of fragments and those
fragments that have anti-coagulant activity are
known as low molecular weight heparin.

5. Heparin
Advantage of LMWH:
1.Better in preventing the venous thrombosis.
2.Given S.C and it is powerful as unfractionated
heparin in prevention and treatment of
pulmonary embolism.
3.Used with success in unstable angina.
4.It doesn’t cross placenta, so it can be given
during pregnancy.
5.It has more prolonged effect than
unfractionated heparin.

6. Heparin
Low molecular weight heparin given S.C
once/twice daily and the dose is calculated
according to the weight of the patient.
The most common examples are:
1.Enoxaparin (Clexane®(
2.Daltaparin
3.Tinazapin (Innohep®(

7. Heparin
Heparin given by I.V or S.C only.
 Rapid onset of effect within 1-2 minutes with
duration of 4-6 hours.
 Bcz of it’s rapid onset it is the first to be used
as anticoagulant treatment.
 Can be given as I.V infusion through infusion
pump and the dilution is either saline or 5%
dextrose.

8. Heparin
*The rate of infusion monitored by measuring the
activated partial thromboplastin time
(aPTT) , 6-hours after starting infusion at least
once daily.
*aPTT should be kept between 1.5 and 2.5 times
the control value.
*abdomen is the best site of injection.

9. Heparin
 Side effects: bleeding at high doses.
 The first sign for bleeding mostly haematuria.
 Prolonged use can cause osteoperosis.
 Very rarely, thrombocytopenia.
 Protamine sulphate reverse the action of
heparin (antidote of heparin(.

10. Coumarins
 These are oral anticoagulats include:
*Warfarin and phenindione.
*Exert their action by the interfering with vitamin
K-dependant clotting factors, especially factors
VII, II, X and XI.

11. Coumarins
 Prothrombin time (PT) should be measured
before starting treatment and the dose adjusted
until the international normalized ratio (INR)
between (depending on the clinical 2.0-
3.5situation(.
 Side effects:
1.rashes, fever and jaundice.
2.Teratogenic effects.
3.hemorrhage.

12. Coumarins
 If hemorrhage happen it can be reverse
rapidly by an infusion of fresh frozen plasma and
phytomenadione (Vitamin K) ,also given as I.V
but it takes 12 hours to become effective.

13. Coumarins
Notes:
1.Warfarin crosses the placenta and should not
be given in the first 3 months of pregnancy.
Instead we use heparin during pregnancy.
2.don’t give anti-coagulants in patients with
active peptic ulcers, severe liver disease or
renal failure.
3.Strict accuracy in the timing of dosing.

14. Fibrinolytics
1.Streptokinase:
*bind to plasminogen and activate it (used to
treat coronary thrombosis(.
It is given by I.V infusion.
 premedications:
1.Hydrocortisone to reduce allergic reactions.
2.Loading dose of oral aspirin which should be
chewed before swallowing.

15. Fibrinolytics
Side effects:
1.Bleeding
2.Allergies (fever(
3.Hypotension
Note : patient develop antibodies of streptokinase
in the body after 4 days of the treatment so the
drug should not be used for at least 12 months
after.

16. Fibrinolytics
2.Alteplase:
*it is a tissue plasminogen activator (tPA(.
*streptokinase antibodies or streptococcal
antibodies (in patient who has been infected by
it) don’t affect alteplase.
*maybe followed by heparin to prevent
reocclusion.

17. Fibrinolytics
3.Antistreplase:
*it is a plasminogen-streptokinase complex.
*given by I.V infusion over 4-5 min and
fibrinolytics activity is sustained for 4-6 hours.

18. Fibrinolytics
-Not given by I.M injection.

19. Antiplatelet drugs
1.Aspirin*
prevent the production of thromboxane in
platelets which causes the aggregation.
*uses:
1.coronary thrombosis with streptokinase.
2.to prevent reoccurrence of coronary
thrombosis.
3.in angina of effort.
4.in unstable angina to prevent the progression
to M.I.

20. Antiplatelet drugs
2.Dipyridamole (presantine®)
(Antiplate®(:
*it is not effective if given alone, combined
with warfarine or aspirin.
3.Fish oil.