Enhanced absorption of Nasulin™, an ultrarapid-acting intranasal insulin formulation, using single nostril administration in normal subjects.

BACKGROUND This pharmacokinetic (PK) study was designed to investigate the maximum intranasal insulin dose that could be achieved by repeated doses in a single nostril of a nasal spray of recombinant regular human insulin 1% in combination with cyclopentadecalactone (CPE-215) 2%, a compound that enhances absorption of molecules across mucous membranes (Nasulin™, CPEX Pharmaceuticals, Inc.). METHOD A nine-period crossover study of 8 healthy, nonsmoking subjects (ages 18-50, body mass index <33 kg/m², weight >70 kg) were studied. In a fasted state, subjects were randomly given 25, 50, and 75 U in a single nostril on the first day and randomly given 50, 75, and 100 U doses utilizing both nostrils on two subsequent days. After a 45-minute PK assessment, subjects were given a meal. To determine the mechanism of enhanced absorption in a single nostril, a second study utilizing 24 subjects under similar conditions received 25 U, placebo (P) that included CPE-215 plus 25 U, and 50 U in a single nostril. RESULTS Single nostril administration revealed enhanced absorption with maximum concentrations (C(max)) of 13, 65, and 96 µU/ml for the 25, 50, and 75 U doses, respectively. Dual nostril administration in two cohorts resulted in C(max) of 31/42, 65/52, and 88/79 µU/ml for the 50, 75, and 100 U, respectively. In the second cohort, C(max) was 23, 19, 56 µU/ml for the 25, P + 25, and 50 U doses, respectively. CONCLUSIONS Repeated dosing in a single nostril resulted in enhanced absorption; this was not due to the increased CPE-215 but to the increased insulin administered.