Pharmacology for Dentistry

Coagulants and Anticoagulants 243

postoperative haemorrhage (cardiac surgery
with cardiopulmonary bypass, coronary
artery bypass grafting), total knee
replacement, gastrointestinal bleeding, local
and general fibrinolysis, epistaxis, prosta
tectomy, haemoptysis and haemorrhage
after dental extraction.

POLIDOCANOL

It is a sclerosing agent for bleeding
oesophageal varices, varicose veins,
bleeding gastroduodenal ulcers etc.

SODIUM TETRADECYL

IV injection causes intimal inflammation
and thrombus formation occluding the
injected vein. Subsequent formation of
fibrous tissue results in partial or complete
vein obliteration.

It is indicated in the treatment of small,
uncomplicated varicose veins of the lower
extremities, haemangioma, ganglionoma,
oesophageal varices.

ANTICOAGULANTS

These are the drugs used to reduce the
coagulability of blood. They can be classified
as in table 6.1.3.

HEPARIN

Heparin is a heterogenous mixture of
sulfated mucopolysaccharides and quick
acting anticoagulant which shows efficacy
both in vitro and in vivo and having a
molecular weight from 4,000 to 40,000
depending upon the type of preparations.
Its biological activity is dependent upon the
plasma protease inhibitor antithrombin III,
which inhibits clotting factor proteases by

forming equimolar stable complexes with

them.

It acts by activating plasma antithrombin

III which rapidly inhibits activated coagulation

factors IXa, Xa, XIa and XIIa, plasmin, kallikrein

and thrombin, thus inhibiting conversion of

fibrinogen to fibrin.

Heparin is well absorbed after subcuta-

neous administration and is not effective

orally, and metabolized mainly in liver. It is

not secreted in milk and does not cross pla-

cental barrier.

Adverse effects include bleeding,

alopecia (reversible), bleeding from gums,

unexplained bruising, osteoporosis and

rarely hypersensitivity, thrombocytopenia

and hyperkalemia.

It is indicated in the prophylaxis and

treatment of deep vein thrombosis in major

surgery and pulmonary embolism,

treatment of atrial fibrillation with

embolisation, prophylaxis and treatment of

peripheral arterial embolism.

LOW MOLECULAR WEIGHT

HEPARINS (LMWH)

These are prepared by enzymatic or

chemical hydrolysis of conventional heparin,

their molecular weight varies from 3,000 to

7,000. They are absorbed more completely

than the conventional heparin preparation

and having longer duration of action.

It is obtained as fragments of commercial

grade heparin which is produced by

chemical or enzymatic depolymerisation. It

contains less pentasaccharide sequences

with a high affinity for antithrombin III.

LMWH exerts its action mostly by anti-

thrombin mediated inhibition of factor Xa.

But some thrombin inhibition by LMWH is