Prostaglandin E2 (PGE2) is synthesized both in the glomeruli and tubules, it lowers the renal vascular resistance and increases renal perfusion through dilatation of the renal vascular bed. The tubular effect of PGE2 is an antagonistic effect of ADH and thus implies local modulation of water and electrolyte transport; however, the major function of the ADH-prostaglandin relationship may be the regulation or renal hemodynamics. ProstaglandinI2 (PGI2) or prostacyclin is synthesized in the glomeruli and mainly affects renal homeostatic mechanisms by antagonizing the vasoconstrictor effects of both norepinephrine and angiotensin II in the vessel. The effects of ANP are also influenced by prostaglandins, since the ANP-related natriuresis seems to depend on redistribution of renal blood flow due to an increase in urinary excretion of prostaglandins and a decrease of renin secretio.
Since prostaglandins are synthezised through COX-enzymes, a beneficial effect of non-steroidal anti-inflammatory drugs in some patients with nocturia is not surprising. A Japanese study in which men with benign prostate hypertrophy (BPH) were treated with loxoprofen because BPH treatment did not improve nocturia, reported in 74% of the cases an improvement or disappearance of nocturia . Treatment of 26 patients with nocturnal polyuria with diclofenac gave a significant decrease in nocturia episodes from 2.7 to 2.3 and a significant decrease in ratio of night time to 24h urine volume from 44% to 39%, however, clinical relevance of these decreases is doubtful. The effect of NSAIDs on nocturia can be explained through several pathways: reduction of urine production at the kidney, decrease in urinary sensation at the bladder, increase of urinary sensation threshold at the central nervous system or alteration of sleep at the brain. However, PGE2 and PGI2 normally only start playing an important role in maintaining GFR in patients with compromised renal hemodynamics. This means that a good effect of NSAIDs is mainly expected in older patients or patients with congestive heart failure, cirrhosis or nephrosis, but since there is a risk of gastric ulcers and deterioration of kidney function, NSAIDs are not indicated to be used in older or precarious patients. Most common reported adverse events in treatment with NSAIDs for nocturia are gastric discomfort, leg edema and urinary frequency in the morning.
(An-Sofie Goessaert, Johan Vande Walle, Ayush Kapila and Karel Everaert- Hormones and Nocturia: Guidelines for Medical Treatment?)
Last date updated on December, 2020