Usefulness of niravoline, an arginine vasopressin inhibitor, on tumour-origin brain oedema.

Niravoline is a selective agonist of kappa-opioid receptors having potent aquaretic activity which may peripherally be mediated in animals. This effect of niravoline is thought to be due to inhibition of arginine vasopressin secretion. Niravoline does not cause an overt excretion of electrolytes that is seen with conventional diuretics, and it is anticipated that niravoline may prove useful in the treatment of oedema. In this study, effect of niravoline on tumour-origin brain oedema was investigated in a brain tumour model created by implantation of C6 glioma cells into the brains of Wistar rats. Five weeks after the tumour cell implantation, niravoline was administered i.v. at 1 mg/kg a total of four times at one-hour intervals. In the control group (i.e., saline or vehicle-treated rats), this brain tumour model was found to result in a statistically significant increase in the water content in selected brain regions remote from the tumour. Administration of niravoline inhibited the increase in the water content in such selected brain regions. Niravoline might be useful on tumour-origin brain oedema clinically.