Absorption of Insulin by Nasal Mucous Membrane. 20

Abstract

The hypodermic injection is the undesirable feature in insulin therapy, and therefore limits its usefulness. Many workers have used oral therapy, viz.: (1) Administering insulin by all enteral and respiratory routes. 1 (2) Adding to insulin: serum, defibrinated blood, bile acids, bile salts, acids, or alcohol, to prevent its destruction or inactivation by the proteolytic ferments of the gastro-intestinal tract. 2 (3) Employing substitutes which possess insulin-like properties. 3 (4) Incorporating the insulin in enteric coated capsules to make it available for absorption after passing the stomach and jejunum. 4 All these have proven to be either toxic or of dubious value. 5

We approached the problem by altering the permeability of the membrane to stimulate absorption of the insulin molecule. The method was based upon the following principles: 1. The membrane should not be exposed to ferments that inactivate insulin. 2. Permeability may be increased by elevating the temperature of the membrane. 6 3. The rate of absorption can be speeded by heating the insulin solution. 4. A “piling up” of the molecule on the membrane may be prevented by lowering the surface tension of the insulin solution. 5. All adhering materials should be mechanically washed away from the membrane. 6. The surface of the membrane should be kept at a favorable pH.

The method consisted of: (1) The nose was irrigated with normal saline, at approximately pH 4, at 40-45°C. This was immediately followed by: (2) Either a solution of Saponin was applied to the mucous membrane, or a few drops of Saponin added to the insulin solution. (3) Insulin at 50°C., was then sprayed directly into the nose with an atomizer, the stem of which had been previously heated. (4) Small plegets of cotton were then inserted into the nares to prevent the patient from blowing out the solution.