Except for fishes and marine mammals, water is a dangerous substances. Its concentration in body tissues requires careful balance, since the dire effects of water depletion are no less threatening than those of water excess. Experience with methylenedioxymethamphetamine (MDMA), the so-called recreational drug "ecstasy", has shown that unwise consumption of water to overcome the parching effects of the drug in conjunction with excessive exercise is liable to induce death by overhydration of brain cells. Even small doses of MDMA have led to collapse, sometimes attributed to heat stroke but now more often to sodium depletion.
One effect of MDMA is to induce a rise in blood vasopressin, released from the hypothalamus. The drug metabolite
4-hydroxy-3-methamphetamine also produces this effect, and is more potent than the original compound. The water retention so caused dilutes the sodium content of the blood, with particular effect on nerve and brain cells.
At the annual meeting of the Society for Endocrinology in London in November, it was reported that the risk of sudden death posed by abuse of MDMA probably depends upon the speed with which an individual can metabolise it, something that is governed by genetic factors, and so is rather unpredictable. It must be emphasised that the "ecstasy"habit should be strenuously avoided — indeed, any concept of a "recreational"drug must be dismissed as a dangerous and misleading one. If the drug has been taken, care must be observed to limit the quantity of water drunk afterwards, and preferably in conjunction with some salt to counteract its effect.