Streptokinase - the revolutionary drug that changed treatment of heart attacks
The most common cause of heart attacks is coronary artery disease (also known as coronary heart disease). Coronary arteries supply oxygen rich blood to the heart. This arteries can slowly become narrow from a build-up of plaque, consisting of fat, cholesterol and other substances. This process of plaque build-up over the years is called atherosclerosis and the resulting condition is coronary artery disease. Eventually, an area of the plaque can rupture.
The body tries to repair the tear by forming a blood clot on the surface of the plaque. This blood clot can partially or completely block blood flow through the affected coronary artery. The heart tissue supplied by the coronary artery dies due to lack of oxygen and other nutrients. This is called heart attack. Earlier the available treatments for heart attacks were mostly preventive and palliative rather than curative. Oxygen was administered for shortness of breath, intravenous fluids were given to prevent dehydration, morphine was given to ease pain and complete bed rest was advised. Aspirin and some oral anticoagulants were tried but there was no reduction in mortality rates. [title] [title] The treatment of heart attacks took a fortunate turn in 1933, when the wonder drug streptokinase was serendipitously discovered by Dr.
W S Tillet. Dr. Tillet in course of one of his experiments, observed that the bacteria Streptococci aggregated together to form clumps in test tubes that contained human plasma. Tillet wondered what was happening.
So he set up a new experiment. He added calcium to oxalated human plasma to form blood clots. Some of these test tubes contained Streptococci bacterial culture.
Tillet noticed that clots in test tubes containing Streptococci dissolved with passage of time. He thus concluded that the bacterium Streptococcus produced some substance that dissolved blood clots. In 1934, Garner and Tillet successfully isolated this substance and showed that it was a protein secreted by the bacterium Streptococcus. The substance was later named streptokinase. In 1958, use of streptokinase in treatment of heart attacks was started. [title] In the normal process of blood clot formation, a prothrombin activator is released at the site of injury.
This in presence of calcium converts blood protein, prothrombin to thrombin. Thrombin in turn converts fibrinogen to fibrin. The protein fibrin forms a mesh entrapping red blood cells, thus forming a blood clot. It was earlier thought that streptokinase acted by directly degrading fibrin. But it was later seen that streptokinase acts in a more indirect way. Streptokinase forms a complex with plasminogen, another plasma protein.
The streptokinase-plasminogen interaction results in a conformational change in plasminogen. Plasminogen is activated. It auto cleaves itself and is converted to plasmin. Plasmin degrades fibrin and dissolves blood clots thus clearing the obstruction in the affected coronary artery and restoring blood flow to the affected heart tissue during heart attack. [title] There are some risks associated with administration of streptokinase injection. There is a risk of haemorrhage (excessive bleeding) at the puncture site and other sites such as gastrointestinal tract and brain. But these bleeding complications are common only in elderly patients or when the streptokinase dose is too high. There is also a small risk of an allergic reaction to the streptokinase molecule due to its bacterial origin.
[title] There are other plasminogen activators available now like tissue plasminogen activator (tPA) and urokinase. Tissue plasminogen activator is produced using recombinant animal cells and urokinase is purified from urine. Of the three major plasminogen activators, streptokinase is most efficient as it is stable for longer time in human body. Also streptokinase is least expensive of the three. It is almost ten times cheaper than tissue plasminogen activator.
Hence, despite the widespread use of tissue plasminogen activator in developed nations, streptokinase remains essential to the management of heart attacks in developing nations. Hi, our channel is all about interesting microorganisms and microbial products. Please subscribe to get more videos about the omnipresent and Omnipotent Microbes.
The most common cause of heart attacks is coronary artery disease (also known as coronary heart disease). Coronary arteries supply oxygen rich blood to the heart. This arteries can…By: Omnipotent Microbes