Effects of dose, pH, and osmolarity on nasal absorption of secretin in rats.

The effects of dose, pH, and osmolarity on the nasal absorption of a secretin solution were studied in rats. The nasal absorption of secretin was determined by measuring the increased secretion of pancreatic juice, and this was compared with the same response on intravenous administration. The relative bioavailability of secretin on intranasal administration compared with intravenous administration, as estimated from the pharmacological response, was approximately one-tenth. It was enhanced in acid solution and reached a maximum in a 0.462 M sodium chloride solution.