VR (Russian VX, Soviet V-gas, Substance 33, R-33) is a "V-series" nerve agent closely related (isomer) to the better-known VX nerve agent.[1]
The development of VR started in the late 1950s by a team from the Soviet Union's Scientific Research Institute No. 42 (NII-42). Sergei Zotovich Ivin, Leonid Soborovsky, and Iya Danilovna Shilakova jointly developed this analogue of VX. They completed their work in 1963 and were later awarded the Lenin Prize for their achievement.[2] A binary weapon comprising two less toxic precursors which mixed during flight to form Substance 33 was later developed by a team led by Nikolai Kuznetsov, for which they were awarded the 1990 Lenin Prize.[3]
In 1972 the Soviets opened a manufacturing plant for VR in Novocheboksarsk.[4] All facilities in USSR produced 15,557 tons of VR according to their declaration to the Organisation for the Prohibition of Chemical Weapons (OPCW),[5] although most if not all of this has now been destroyed under disarmament treaties.[6]
VR has similar lethal dose levels to VX (between 10–50 mg) and has similar symptoms and method of action to other nerve agents that act on cholinesterase, and treatment remains the same. However, the window for effectively treating second generation V series seizures is shorter, as they rapidly denature the acetylcholinesterase protein in a similar manner to soman, making treatment with the standard nerve gas antidote pralidoxime ineffective unless it is given very soon after exposure. Pre-treatment with pyridostigmine prior to exposure, and treatment with other drugs such as atropine and diazepam after exposure, will reduce symptoms of nerve agent toxicity but may not be sufficient to prevent death if a large dose of nerve agent has been absorbed. In addition to the standard seizures, some of the second generation V series agents are known to cause comas.
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