Insulin drug delivery systems: rectal gels.

In continuation of a previous study on insulin gels administered deep rectally by means of an applicator, 16 further rectal formulations were evaluated, using the nondiabetic White New Zealand rabbit as animal model. The highest pharmacologic availability, P.A., defined as the ratio of the areas under the % glucose reduction-time curves rectally versus I.V., corrected for dose size and body weight, in the previous experiments was about 29%. In the present study the highest mean P.A. was 42% and 31%, both obtained with Gelucire bases (50/22 and 44/14), pH 8 buffer solution and sodium deoxycholate, using Cab-O-Sil as stiffening agent. Simple gels prepared from gelatine and polyethylene glycol, or Veegum, resulted in mean P.A. of about 23 and 24%, respectively. Addition of Gelucire or sodium deoxycholate did not result in a further increase of P.A. of the latter two gels.