Snake venom as medicine
Have you ever thought about the deadliest venoms that take our lives are used as drugs in saving them too ?
Yes, there are some venoms in nature which are being used to treat some disorders. Venoms are cocktails made up of between ten to hundreds of different toxins, usually proteins and smaller chains of amino acids similar to proteins called peptides, along with organic molecules such as hormones, antibodies and other compounds that are involved in metabolic functions of living things.
Snake venoms have been used as medical tools for thousands of years especially in traditional Chinese medicine. Their venoms are mostly used in treating cardiovascular disorders. Each species venom contains an approximate of hundred different molecules and are used effectively for defense and predation. The venoms effect black outs from a fall in blood pressure in the victim leaving them trapped and ready to be eaten.
Common venom components can be classified as enzyme and non-enzyme components. Enzymatic snake venoms include phospholipase A2, L - amino acid oxidases, metalloproteases, serine protease, acetylcholinesterases and hyaluronidases. Non-enzymatic compounds include disintegrins, three-finger toxins, Kunitz peptides, cysteine- rich secretory proteins, C type lectins and natriuretic peptides.
Here are few drugs which are derived from the snake venom:
The first drug derived from the snake venom toxin. It is taken from a Brazillian pit viper and acts as an angiotensin converting enzyme (ACE) inhibitor. Captopril main uses are based on its vasodilation and inhibition of some renal function activities hence used to treat hypertension, cardiac conditions such as congestive heart failure and after myocardial infraction, preservation of kidney function in diabetic nephropathy. It has also been investigated for use in the treatment of cancer.
Captopril blocks the conversion of angiotensin I to angiotensin II and prevents the degradation of vasodilatory prostaglandins, inhibiting vasoconstriction and promoting systemic vasodilation. It is not administered as prodrug. It is partially metabolised and partly excreted unchanged in urine. Adverse effects of the drug include cough, itching, headache, tachycardia,chest pain, palpitations, weakness.
This is an antiplatelet drug of glycoprotein inhibitor. It is a cyclic heptapeptide derived from a disintegrin protein found in venom of the southeastern Pygmy rattlesnake. Eptifibatide is used to reduce the risk of acute cardiac ischemic events in patients with unstable angina or non-ST segment-elevation, myocardial infraction. The drug is usually applied together with aspirin or clopidogrel and heparin. Angiographic evaluation and other intensive diagnostic procedures may be considered a first task before initiating therapy with eptifibatide. The drug should exclusively be used in hospitalized patients both because of serious degree of patient's illness and because of possible side effects of eptifibatide.
Some precautions and contraindications should be considered :
#Pregnant patients should be treated only when clearly needed.
#Breastfeeding should be avoided during treatment in order to prevent damage to the newborn.
#Geriatric patients should be very closely observed for bleeding and other side effects.
#The drug is contraindicated in patients with platelet counts of less than 100,000 per μl because no clinical experience exists regarding such patients.
#Coagulation parameters such as ACT,aPTT,TT and PT should be followed closely during therapy and afterwards.
#Severe, uncontrolled hypertension.
#Eptifibatide is not indicated in patients below 18yrs of age.
Severe bleeding is the major adverse event accounting 4.4 to 4.7% in patients, thrombocytopenia accounts 0.2%, hypotension 6%, cardiovascular failure 2%, serious arrhythmias (ventricular fibrillation 1.5%,atrial fibrillation 6%), severe allergic reactions 0.2%. These reactions can be life threatening and maybe due to the peptide character of eptifibatide.
Batroxobin also known as reptilase , a snake venom enzyme with Venombin A activity. It is produced by the venomous species of pit viper found in east of the Andes of South America. It is a hemotoxin which acts as a serine protease similarly to thrombin and functions as an defibrinogenating agent and is used for patients with thrombosis. Studies showed the uses of batroxobin as a replacement test for the more commonly used thrombin time. The enzyme is unaffected by heparin, it is mostly used when heparin is present in the blood. Studies emphasize the improving uses in surgery, mostly spinal surgery and used as serine protease. Batroxobin isolated from venom is highly irregular in quality,it is now more often synthesized in organisms using Bothrops moojeni cDNA. The amino acid sequence exhibited significant homology with other known mammalian serine proteases, such as trypsin,thrombin, and pancreatic kallikrein. Therefore it was concluded that it is a member of serine protease family.
Normally the venom is directly injected into the bloodstream by snake venom. They are also administered intravenously by giving a dose three times a day. Batroxobin is excreted by liver, kidney and spleen. Excretion of this drug can be detected by small metabolic molecules in urine. An overdose of batroxobin will eventually lead to death due to hemostatic effects. No safe dose has been determined in humans yet. Only lethal dose for mice has been studied.