Ibuprofen augments gastrointestinal symptoms in lactose maldigesters during a lactose tolerance test.

BACKGROUND

Clinical symptoms during lactose tolerance test mimic those seen after therapeutic administration of prostaglandins, and resemble inflammatory processes.

AIM: To investigate the possibility that lactose-induced gastrointestinal symptoms are associated with prostaglandins and/or nitric oxide.

METHODS

After an overnight fast, nine maldigesters ingested lactose or sucrose with or without an inhibitor of prostaglandin synthesis (ibuprofen), in a randomised double-blind crossover trial. Gastrointestinal symptoms, concentrations of PGE2-M in blood and urine, and urinary 6-keto PGF1alpha (as indicators of prostaglandin synthesis), and urinary nitrate and nitrite as well as cyclic GMP excretions (as indicators of nitric oxide formation), were measured.

RESULTS

Ibuprofen increased the first 3-h symptom scores (flatulence + borborygmi + abdominal bloating + pain) caused by lactose (P=0.008) but not sucrose. The concentrations of PGE2-M in the plasma and in the urine were unaffected. Lactose increased the urinary excretion of 6-keto PGF1alpha by about 30% (P=0.17), which was inhibited by ibuprofen (P=0.02). The production of nitric oxide was unaffected by lactose or ibuprofen.

CONCLUSION

The inhibition of prostaglandin synthesis intensified gastrointestinal symptoms in lactose maldigesters, suggesting a negligible role for prostanoids in lactose-induced symptoms.