Insulin nanoparticles: a novel formulation approach for poorly water soluble Zn-insulin.
OBJECTIVE
To determine the feasibility of using wet milling technology to formulate poorly water soluble zinc-insulin as a stable, biologically active, nanoparticulate dispersion.


METHODS
The feasibility of formulating zinc-insulin as a nanoparticulate dispersion using wet milling technology was studied. An insulin nanoparticulate formulation was reproducibly obtained after milling zinc-insulin in the presence of F68, sodium deoxycholate and water at neutral pH. The physical and chemical properties of these peptide particles were studied using electron microscopy, laser light scattering, HPLC and SDS-PAGE. To verify efficacy, hyperglycemic rats were dosed subcutaneously and intraduodenally with nanoparticles or solubilized insulin. Glucose and insulin levels were monitored on blood samples collected throughout the study.


RESULTS
Zn-insulin (mean size = 16.162 microm) was processed using milling technology to form an aqueous-based nanoparticle dispersion with a mean particle size of less than 0.150 microm. The formulation was homogeneous and exhibited a unimodal particle size distribution profile using laser light diffraction techniques. Insulin, processed as a peptide-particle dispersion, was shown to be comparable to unprocessed powder using HPLC and SDS-PAGE. In addition, HPLC analyses performed on samples, heat-treated at 70 degrees C for 100 minutes, demonstrate that under conditions which effect the solubilized peptide, formulated as a peptide-particle dispersion, insulin was chemically stable. Also, when stored refrigerated, the insulin dispersion was chemically and physically stable. Finally, peptide particles of insulin, dosed subcutaneously and intraduodenally, were effective at lowering blood glucose levels of hyperglycemic rats.


CONCLUSIONS
Water insoluble Zn-insulin can be formulated as a stable, biologically active nanometer-sized peptide particle dispersion using wet media milling technology.
Merisko-Liversidge
Elaine
E
Elan NanoSystems, 3500 Horizon Dr., King of Prussia, PA 19406, USA. elaine.liversidge@elan.com
McGurk
Simon L
SL
Liversidge
Gary G
GG
D000818:Animals; D002626:Chemistry, Pharmaceutical; D002851:Chromatography, High Pressure Liquid; D004353:Drug Evaluation, Preclinical; D004591:Electrophoresis, Polyacrylamide Gel; D006943:Hyperglycemia / Q000188:drug therapy; D007328:Insulin / Q000008:administration & dosage* / Q000737:chemistry; D008297:Male; D049329:Nanostructures / Q000737:chemistry / Q000648:ultrastructure; D010316:Particle Size; D051381:Rats; D017208:Rats, Wistar; D012995:Solubility
D007328:Insulin