Vampire bats and Malaysian pit vipers' mouths are potentially lethal, producing life taking and life-saving substances according to Chron.com and AFP.

Vampire bats found in Central and South America feed exclusively on blood and needs to consume at least two tablespoons of blood each day. The bat's saliva contains a substance that is capable of stopping the prey's blood from coagulating, thus allowing the blood to flow freely.

The Malaysian pit viper of Southeast Asia, on the other hand is equipped with a hemotoxin. This sophisticated chemical kills prey by causing its blood to stop coagulating. When the viper bites a rat, the rat suffers a massive hemorrhage and quickly bleeds to death.

"These chemicals are very powerful and very complex, and the animals use them to survive. We are using them to help people survive strokes and lessen the damage they do," according to Dr. David Chiu, a neurologist and medical director of the Eddy Scurlock Stroke Center at the Methodist Neurologic Institute in Houston.

Dr. Chiu heads the clinical trial testing of the effectiveness of the two venoms on patients who have suffered strokes. Strokes occur when blood flow to a region of the brain is obstructed or compromised. Lack of oxygen and glucose flowing to the brain leads to death of brain cells. If enough time lapses without treatment, brain damage often results in impairment in speech, movement and memory as well.

Strokes, which are mostly caused by arterial blockage, are the number 3 cause of death in the United States, killing almost 163,000 people each year. About 700,000 Americans suffer new or recurrent strokes .

According to Stroke Foundation of Australia, stroke is Australia's second single greatest killer after coronary heart disease and a leading cause of disability. In 2011, Australians will suffer around 60,000 new and recurrent strokes - that's one stroke every 10 minutes. One in five people having a first-ever stroke die within one month and one in three die within a year.

Drugs being tested by Dr. Chiu are intended for emergency use, not for prevention of strokes. The sooner the stroke patient receives the powerful anticoagulant to remove the obstruction and restore flow of the blood to the brain, the better the prognosis. Thus, patient's survival is likely to increase and suffer less disability.

"We can't waste time," Chiu said. "Time is brain."

From the clot-busting chemical found in the saliva of vampire bats, researchers have genetically engineered a medication called Desmoteplase. Much excitement is generated with the development of the drug because it can be effectively administered to a patient up to nine hours after the initial appearance of the stroke symptoms.

The other trial involves Viprinex which utilizes the compound called ancrod found in the venom of the Malaysian pit viper. Dr. Chiu and his colleagues would like to determine if a one-time dose of Viprinex administered to ischemic stroke victims may facilitate improved neurological function.

Doctors have about 3 hour window time to treat stroke patients with the U.S. FDA approved thrombolytic, t-PA (tissue plasminogen activator), before blood clots become fatal or cause permanent damage to the brain. The vampire saliva could hold the key to extending the window time of treatment and subsequently reducing the effects of the stroke.

Dr. Chiu hopes to test the drugs on at least 1,000 patients, and expects the trials to last for at least two years.