Hormonal, Haemodynamic, and Subjective Effects of Intravenously Infused Indomethacin: No Change in the Physiological Response to Hypertonic Saline Challenge

: This double-blind, placebo-controlled human study was performed to determine the endocrine responses to intravenously administered indomethacin at two dose rates (0.36 or 0.72 mg/kg bolus followed by 0.071 or 0.143 mg/kg/hr for 150 min.). A 5% hypertonic saline infusion was used for further assess the hormonal systems regulating body fluid and electrolyte balance. Plasma renin activity (PRA) and concentrations of aldosterone and vasopressin (AVP) were unaffected by indomethacin. Hypertonic saline caused a 5% increase in plasma sodium and a 4.2% increase in serum osmolality, with a concomitant two-fold rise in plasma AVP levels and significant declines in PRA and aldosterone. Indomethacin had no effects on these responses, and did not affect plasma catecholamine concentrations, but the hypertonic saline infusion doubled the noradrenaline levels in plasma. Atrial natriuretic peptide (ANP) -like immunoreactivity in plasma was not affected by indomethacin nor by hypertonic saline. The higher dose rate of indomethacin resulted in significant stimulation of growth hormore release, but plasma prolactin levels were not influenced. Thus acute intravenous administration of indomethacin proved to be devoid of significant effects on the multihormonal system regulating fluid and electrolyte balance.