Determination of a Suitable Dosage of Lysine-Vasopressin and Triglycyl-Lysine-Vasopressin, Given in a Gel-Solution Locally in the Rectum of Rats for Possible Radioprotective Purposes

Abstract

In order to develop a method for selective radioprotection of the rectal mucosa, a dose–response study was carried out using triglycyl-lysine-vasopressin and lysine-vasopressin. The vasopressin was dissolved in a gel-solution of either Blanose (sodium-carboxymethyl–cellulose), Klucel (hydroxypropyl-cellulose) or Natrosol (hydroxyethyl-cellulose). The solution had a higher viscosity than water thus enabling rectal administration of the drug without any operative measures. The maximum vasopressin dose that can be given without causing any significant changes in systemic circulation was determined for the different solutions and vasopressins. For triglycyl-lysine-vasopressin this dose was 1 600 μg when it was dissolved in Blanose and 128 μg when dissolved in Natrosol. Lysine-vasopressin could be given in a maximum dose of 16 μg dissolved in Natrosol. Klucel solution did not seem suitable for this purpose. For further investigations, 16 μg lysine-vasopressin dissolved in Natrosol seems to be the most promising combination.