Heparin

UNDER REVIEW (September 2016)

Mechanism of Action:

Heparin is an acidic mucopolysaccharide found especially in lung and liver tissue and having the ability to prevent the clotting of blood, used in the treatment of thrombosis. Heparin works by potentiating the action of antithrombin III, as it is similar to the heparan sulphate proteoglycans which are naturally present on the cell membrane of the endothelium. Because antithrombin III inactivates many coagulation proteins (especially those of the intrinsic cascade), the process of coagulation will slow down.

Lecture and CAL materials:

Warfarin

UNDER REVIEW (September 2016)

Mechanism of Action:

Warfarin inhibits the vitamin K-dependent synthesis of biologically active forms of the calcium-dependent clotting factors II, VII, IX and X, as well as the regulatory factors protein C, protein S, and protein Z. Other proteins not involved in blood clotting, such as osteocalcin, or matrix Gla protein, may also be affected. Warfarin consists of a racemic mixture of two active enantiomers: R- and S- forms, each of which is cleared by different pathways. S-warfarin has five times the potency of the R-isomer with respect to vitamin K antagonism.

Lecture and CAL materials:

Simvastatin

Indications

  • Treatment of hypercholesterolaemia or mixed dyslipidaemia
  • Reduction of cardiovascular morbidity and mortality in patients with a risk
  • Management of peripheral vascular diseases

Mechanism of Action

Statins are 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors. HMG-CoA reductase is the rate-determining enzyme in cholesterol synthesis. Reduced intracellular cholesterol concentrations activate a cellular signaling cascade that results in the up-regulation of the gene coding for synthesis of LDL receptors. Increased LDL receptors (mainly in hepatocytes) cause increased LDL uptake into cells, resulting in lower plasma LDL levels. Simvastatin is an inactive pro-drug which is metabolized to its active form in the liver.

Lecture and CAL materials: