Evaluation of novel particles as pulmonary delivery systems for insulin in rats.

The purpose of the study was to evaluate the influence of calcium phosphate (CAP) and polyethylene glycol (PEG) particles on the systemic delivery of insulin administered by the pulmonary route. Two methods of pulmonary delivery were employed: intratracheal instillation and spray instillation. Insulin-CAP-PEG particles in suspension (1.2 U/kg, 110-140 micro L) were administered to the lungs of fasted rats by intratracheal instillation (INCAPEG) or spray instillation (SINCAPEG). Control treatments consisted of insulin solution (1.2 U/kg) by intratracheal instillation, spray instillation, and subcutaneous administration (SC). Plasma concentrations of insulin and glucose were determined by chemiluminescence and colorimetric methods, respectively. Data were analyzed by compartmental and non-compartmental methods, and pharmacokinetic (PK) and pharmacodynamic (PD) parameters of insulin disposition were determined. PK analysis suggested that insulin administered in particles had a longer half-life, a longer mean residence time, and a smaller rate of elimination than insulin in solution. In addition, insulin bioavailability after SINCAPEG was 1.8-fold that of insulin solution administered SC. PD analysis showed that smaller areas under the effect curve and, conversely, larger areas above the effect curve were obtained after INCAPEG in comparison to insulin solution. The magnitude of this effect was increased after SINCAPEG. The presence of CAP-PEG particles appears to positively influence the disposition of insulin administered to the lungs of Sprague-Dawley rats. Spray instillation appears to be a more efficient method of delivering insulin to the lungs of rats than intratracheal instillation.

Calcium phosphate nanoparticles induce mucosal immunity and protection against herpes simplex virus type 2.

Previously we reported that calcium phosphate nanoparticles (CAP) represented a superior alternative to alum adjuvants in mice immunized with viral protein. Additionally, we showed that CAP was safe and elicited no detectable immunoglobulin E (IgE) response. In this study, we demonstrated that following mucosal delivery of herpes simplex virus type 2 (HSV-2) antigen with CAP, CAP adjuvant enhanced protective systemic and mucosal immunity versus live virus. Mice were immunized intravaginally and intranasally with HSV-2 protein plus CAP adjuvant (HSV-2+CAP), CAP alone, phosphate-buffered saline, or HSV-2 alone. HSV-2+CAP induced HSV-specific mucosal IgA and IgG and concurrently enhanced systemic IgG responses. Our results demonstrate the potency of CAP as a mucosal adjuvant. Furthermore, we show that systemic immunity could be induced via the mucosal route following inoculation with CAP-based vaccine. Moreover, neutralizing antibodies were found in the sera of mice immunized intranasally or intravaginally with HSV-2+CAP. Also, the results of our in vivo experiments indicated that mice vaccinated with HSV-2+CAP were protected against live HSV-2 infection. In conclusion, these preclinical data support the hypothesis that CAP may be an effective mucosal adjuvant that protects against viral infection.