Elisabetta Muntoni1, Elisabetta Marini1, Nahid Ahmadi2, Paola Milla1, Corrado Ghè1, Alessandro Bargoni3, Maria Teresa Capucchio4, Elena Biasibetti5, Luigi Battaglia6. 1. Dipartimento di Scienza e Tecnologia del Farmaco, Università degli Studi di Torino, Via Pietro Giuria 9, Turin, Italy. 2. Department of Chemistry, University of Sistan and Baluchistan, University Boulevard, Zahedan, Iran. 3. Dipartimento di Scienze della Sanità Pubblica e Pediatriche, Università degli Studi di Torino, Piazza Polonia 94, Turin, Italy. 4. Dipartimento di Scienze Veterinarie, Università degli Studi di Torino, Largo Paolo Braccini 2, Grugliasco, Italy. 5. Histopathology Department CIBA, Istituto Zooprofilattico Sperimentale del Piemonte, Via Bologna 148, Turin, Italy. 6. Dipartimento di Scienza e Tecnologia del Farmaco, Università degli Studi di Torino, Via Pietro Giuria 9, Turin, Italy. luigi.battaglia@unito.it.
Abstract
AIMS: Subcutaneous administration of insulin in patients suffering from diabetes is associated with the distress of daily injections. Among alternative administration routes, the oral route seems to be the most advantageous for long-term administration, also because the peptide undergoes a hepatic first-pass effect, contributing to the inhibition of the hepatic glucose output. Unfortunately, insulin oral administration has so far been hampered by degradation by gastrointestinal enzymes and poor intestinal absorption. Loading in lipid nanoparticles should allow to overcome these limitations. METHODS: Entrapment of peptides into such nanoparticles is not easy, because of their high molecular weight, hydrophilicity and thermo-sensitivity. In this study, this objective was achieved by employing fatty acid coacervation method: solid lipid nanoparticles and newly engineered nanostructured lipid carriers were formulated. Insulin and insulin analog-glargine insulin-were entrapped in the lipid matrix through hydrophobic ion pairing. RESULTS: Bioactivity of lipid entrapped peptides was demonstrated through a suitable in vivo experiment. Ex vivo and in vivo studies were carried out by employing fluorescently labelled peptides. Gut tied up experiments showed the superiority of glargine insulin-loaded nanostructured lipid carriers, which demonstrated significantly higher permeation (till 30% dose/mL) compared to free peptide. Approximately 6% absolute bioavailability in the bloodstream was estimated for the same formulation through in vivo pharmacokinetic studies in rats. Consequently, a discrete blood glucose responsivity was noted in healthy animals. CONCLUSIONS: Given the optimized ex vivo and in vivo intestinal uptake of glargine insulin from nanostructured lipid carriers, further studies will be carried out on healthy and diabetic rat models in order to establish a glargine insulin dose-glucose response relation.
AIMS: Subcutaneous administration of insulin in patients suffering from diabetes is associated with the distress of daily injections. Among alternative administration routes, the oral route seems to be the most advantageous for long-term administration, also because the peptide undergoes a hepatic first-pass effect, contributing to the inhibition of the hepatic glucose output. Unfortunately, insulin oral administration has so far been hampered by degradation by gastrointestinal enzymes and poor intestinal absorption. Loading in lipid nanoparticles should allow to overcome these limitations. METHODS: Entrapment of peptides into such nanoparticles is not easy, because of their high molecular weight, hydrophilicity and thermo-sensitivity. In this study, this objective was achieved by employing fatty acid coacervation method: solid lipid nanoparticles and newly engineered nanostructured lipid carriers were formulated. Insulin and insulin analog-glargineinsulin-were entrapped in the lipid matrix through hydrophobic ion pairing. RESULTS: Bioactivity of lipid entrapped peptides was demonstrated through a suitable in vivo experiment. Ex vivo and in vivo studies were carried out by employing fluorescently labelled peptides. Gut tied up experiments showed the superiority of glargineinsulin-loaded nanostructured lipid carriers, which demonstrated significantly higher permeation (till 30% dose/mL) compared to free peptide. Approximately 6% absolute bioavailability in the bloodstream was estimated for the same formulation through in vivo pharmacokinetic studies in rats. Consequently, a discrete blood glucose responsivity was noted in healthy animals. CONCLUSIONS: Given the optimized ex vivo and in vivo intestinal uptake of glargineinsulin from nanostructured lipid carriers, further studies will be carried out on healthy and diabeticrat models in order to establish a glargineinsulin dose-glucose response relation.