Comparison of the effects of various transmucosal absorption promoters on buccal insulin delivery

Abstract

We have evaluated the effects of various classes of transmucosal and transdermal absorption promoters on buccal insulin absorption in rats. Insulin absorption was estimated from the cumulative response of plasma glucose concentrations and by comparison to an i.m. dose/response curve. In the absence of an absorption promoter, buccal insulin was less than 4% as effective as i.m. insulin. All steroidal detergents examined as absorption promoters markedly improved buccal insulin absorption, using aqueous vehicles containing 5% adjuvant. Concentrations greater than 1% were required. The non-ionic surfactant, laureth-9, was also an effective absorption promoter and was effective at lower concentrations. Ester non-ionic surfactants had no effects. The effect of pH was evaluated for sodium fusidate and laureth-9 vehicles, and with both adjuvants buccal insulin absorption was lower at pH 5.4 than at pH 3.4 or pH 7.4. Other effective absorption promoters included sodium lauryl sulfate, sodium laurate (at pH 8.9), palmitoyl carnitine, and a lauric acid/propylene glycol vehicle. With the most effective absorption-promoting vehicles, buccal insulin was one-fourth to one-third as effective as i.m. insulin. © 1989.