INOSITOL MAY REVERSE LITHIUM-INDUCED POLYDIPSIA BUT NOT POLYURIA

A previous open study suggested that oral inositol 3 g/day ameliorates lithium-induced polyuria-polydipsia as rated subjectively by patients . We designed a double-blind crossover study of 6 g/day oral inositol versus placebo, each given for 2 weeks, in seven patients. Inositol di d not reverse lithium-induced polyuria, as measured by 24 h urine volu me and urine specific gravity. However, subjects' subjective report of symptomatology was significantly improved on inositol as compared to placebo, possibly due to alleviation of polydipsia. Inositol was previ ously shown to reverse lithium-induced polydipsia in rats. Such a phen omenon may be mediated by either a central or a peripheral mechanism. In order to study such suggested mechanisms, we injected daily inosito l or artificial CSF i.c.v. to rats exhibiting lithium-induced polydips ia. Inositol i.c.v. reversed lithium-induced polydipsia, but kidney in ositol levels in Li-treated rats were not different from controls. The se findings suggest that inositol may alleviate symptoms of lithium-in duced polydipsia via a central effect, but has no direct effect on lit hium-induced polyuria. (C) 1997 John Wiley & Sons, Ltd.