However, internet advertising for organs is a highly controversial practice, as some scholars believe it undermines the traditional list-based allocation system.The National Transplant Organization of Spain is one of the most successful in the world (Spain has been the world leader in organ donation for decades), but it still cannot meet the demand, as 10% of those needing a transplant die while still on the transplant list. Donations from corpses are anonymous, and a network for communication and transport allows fast extraction and transplant across the country. Under Spanish law, every corpse can provide organs unless the deceased person had expressly rejected it. Because family members still can forbid the donation, carefully trained doctors ask the family for permission, making it very similar in practice to the United States system.In the overwhelming majority of cases, organ donation is not possible for reasons of recipient safety, match failures, or organ condition. Even in Spain, which has the highest organ donation rate in the world, there are only 35.1 actual donors per million people, and there are hundreds of patients on the waiting list. This rate compares to 24.8 per million in Austria, where families are rarely asked to donate organs, and 22.2 per million in France, which—like Spain—has a presumed-consent system. Prison inmates
In the United States, prisoners are not discriminated against as organ recipients and are equally eligible for organ transplants along with the general population. A 1976 U.S. Supreme Court case ruled that withholding health care from prisoners constituted "cruel and unusual punishment".
Its use in hepatically impaired individuals is also not recommended, as is its use in cases of pre-existing hypothyroidism.Its use in pregnant women is advised against, although the available evidence suggests it may be safe, provided maternal pH and cyanide levels are closely monitored. Some evidence suggests sodium nitroprusside use in critically ill children may be safe, even without monitoring of cyanide level. Interactions
The only known drug interactions are pharmacodynamic in nature, that is it is possible for other antihypertensive drugs to reduce the threshold for dangerous hypotensive effects to be seen. Overdose
Due to its cyanogenic nature, overdose may be particularly dangerous. Treatment of sodium nitroprusside overdose includes the following:
Discontinuing sodium nitroprusside administration
Buffering the cyanide by using sodium nitrite to convert haemoglobin to methaemoglobin as much as the patient can safely tolerate
Infusing sodium thiosulfate to convert the cyanide to thiocyanate.Haemodialysis is ineffective for removing cyanide from the body but it can be used to remove most of the thiocyanate produced from the above procedure. Toxicology
The cyanide can be detoxified by reaction with a sulfur-donor such as thiosulfate, catalysed by the enzyme rhodanese. In the absence of sufficient thiosulfate, cyanide ions can quickly reach toxic levels. Hydroxocobalamin can be administered to reduce the risk of thiocyanate toxicity induced by nitroprusside. Mechanism of action
As a result of its breakdown to nitric oxide (NO), sodium nitroprusside has potent vasodilating effects on arterioles and venules (arterial more than venous), whereas other nitrates exhibit more selectivity for veins (e.g. nitroglycerin).Sodium nitroprusside breaks down in circulation to release nitric oxide (NO).