Questions 34-44 refer to the following information.
Toxic Snail Kills the Pain
The Conus magus is a predatory and venomous marine snail that is protected by a beautiful shell; 34 their name translates to “magical cone.” The shell size of an adult ranges from 16 mm to 94 mm, or from a half inch to three inches long. The shell resembles striped chocolate or chestnut coloring on white. The Conus magus is found in many parts of the globe—including the Red Sea, the Indian Ocean, the Mascarene Basin, and parts of the Pacific.
35 While the Conus magus is a fascinating species in its own right, humans are primarily interested in one aspect of the species: the medicinal qualities of its venom. The venom of the Conus magus contains conotoxins, a group of neurotoxic peptides, specific to this species of snail. The majority of these peptides are lethal to humans, 36 and one is highly beneficial. Scientists have developed ziconotide, a synthetic chemical, from one of these singular neurotoxic peptides. 37 It is one of the most highly effective pain-killers known to man; its potency is 1000 times that of morphine. Ziconotide works by blocking calcium channels, which are located in pain-transmitting nerve cells within the 38 brain, heart, the nervous system, and bone. This blockage prevents the calcium channels from transmitting pain signals to the brain.
In 2004, the U.S. Food and Drug Administration 39 approved the use of Prialt, the ziconotide from snail toxin, as a prescribed painkiller. Prialt has not gained the widespread use of morphine and other less potent painkillers, 40 because of its remarkable effectiveness. This is largely due to the fact that Prialt is difficult to administer. The only way to administer the drug is to 41 have injected it into the spine, a very painful procedure. Largely due to this difficulty, Prialt has only been used to treat chronic and severe pain caused by such diseases as AIDS, cancer, and neurological disorders.
(1) Prialt has to be injected because it cannot cross the blood-brain barrier, 42 a sort of membrane that blocks compounds within the blood from entering the brain. (2) However, in the last year, scientists have been working on a way to administer Prialt in a less painful way. (3) One proposed delivery solution is hiding Prialt in something that can cross the blood-brain barrier. (4) Referred to as the “Trojan Horse strategy,” the process places the chemical inside a tiny container constructed from viral proteins. 43
Although still in the research phase, this 44 solution could be the key to widespread Prialt use. If this delivery method works it could lead to a vast reduction of untreated pain for long-suffering patients.
