Inspecting Insulin Products Using Water Proton NMR. I. Noninvasive vs Invasive Inspection

Background: There is a clear need to transition from batch-level to vial/syringe/pen-level quality control of biologic drugs, such as insulin. This could be achieved only by noninvasive and quantitative inspection technologies that maintain the integrity of the drug product. Methods: Four insulin products for patient self-injection presented as prefilled pens have been noninvasively and quantitatively inspected using the water proton NMR technology. The inspection output is the water proton relaxation rate R2(1H2O), a continuous numerical variable rather than binary pass/fail. Results: Ten pens of each product were inspected. R2(1H2O) displays insignificant variation among the 10 pens of each product, suggesting good insulin content uniformity in the inspected pens. It is also shown that transferring the insulin solution out of and then back into the insulin pen caused significant change in R2(1H2O), presumably due to exposure to O2 in air. Conclusions: Water proton NMR can noninvasively and quantitatively inspect insulin pens. wNMR can confirm product content uniformity, but not absolute content. Its sensitivity to sample transferring provides a way to detect drug product tampering. This opens the possibility of inspecting every pen/vial/syringe by manufacturers and end-users.

Development, Characterization, and Ex Vivo Assessment of Elastic Liposomes for Enhancing the Buccal Delivery of Insulin

Buccal drug delivery is a suitable alternative to invasive routes of drug administration. The buccal administration of insulin for the management of diabetes has received substantial attention worldwide. The main aim of this study was to develop and characterize elastic liposomes and assess their permeability across porcine buccal tissues. Sodium-cholate-incorporated elastic liposomes (SC-EL) and sodium-glycodeoxycholate-incorporated elastic liposomes (SGDC-EL) were prepared using the thin-film hydration method. The prepared liposomes were characterized and their ex vivo permeability attributes were investigated. The distribution of the SC-EL and SGDC-EL across porcine buccal tissues was evaluated using confocal laser scanning microscopy (CLSM). The SGDC-EL were the most superior nanocarriers since they significantly enhanced the permeation of insulin across porcine buccal tissues, displaying a 4.33-fold increase in the permeability coefficient compared with the insulin solution. Compared with the SC-EL, the SGDC-EL were better at facilitating insulin permeability, with a 3.70-fold increase in the permeability coefficient across porcine buccal tissue. These findings were further corroborated based on bioimaging analysis using CLSM. SGDC-ELs showed the greatest fluorescence intensity in buccal tissues, as evidenced by the greater shift of fluorescence intensity toward the inner buccal tissue over time. The fluorescence intensity ranked as follows: SGDC-EL > SC-EL > FITC–insulin solution. Conclusively, this study highlighted the potential nanocarriers for enhancing the buccal permeability of insulin.

Preparation and characteristics of W/O microemulsion stabilized with polyglycerylpolyricinoleate as a potential system for oral insulin delivery

Aim. The aim of the present work was to develop the composition and study the characteristics of water-in-oil microemulsion stabilized with polyglycerylpolyricinoleate — Tween 80 — ethanol mixture as a potential system for oral insulin delivery. Materials and methods. To determine the boundaries of the regions of existence of water-in-oil microemulsion in the pseudo-three component systems water — polyglycerylpolyricinoleate (PG-3-PR, Gobiotics BV, Netherlands)/ Tween 80/ethanol — paraffin oil, mixtures of paraffin oil and surfactants with oil — surfactant ratios from 9.5:0.5 to 0.5: 9.5 (wt.) were thoroughly mixed and titrated with an aqueous phase (distilled water).Compositions with the value of hydrophilic-lipophilic balance of the PG-3-PR — Tween 80 mixture equal to 6.15 were studied. Among several types of formed systems, a single-phase region corresponding to a homogeneous, optically transparent, liquid water-in-oil microemulsion was determined. The kinetic and thermodynamic stability of a number of compositions, including those containing insulin (Actrapid HM, Novo Nordisk А/С, Denmark), was studied. The values of the effective viscosity of microemulsions at different ratios of surfactant — oil and surfactant — co-surfactant were determined using a vibration viscometer. Based on the results obtained, a composition was selected to study the kinetics of insulin release into a model environment that simulated the environment of the small intestine. Insulin solution (the control sample) and the insulin-containing microemulsion were placed in the dialysis bags and immersed in 50 mL of PBS (pH 7.4) in a shaking incubator at 180 rpm and 37 ° С. At predetermined intervals, the aliquots of dissolution media were withdrawn, and the concentration of the released peptide was determined by the Bradford assay using a UV spectrophotometer at 595 nm. Results. The composition with 9:1 surfactant — co-surfactant ratio, containing 10 % of the aqueous phase (an insulin solution with a concentration of 100 IU / ml), which remained stable both during three cycles of freezing/thawing and heating/cooling, and after long-term storage at room temperature, was selected to study the kinetics of in vitro release of the peptide into the model medium. The effective viscosity of the sample was 2.4±0.04 Pa.s. The microemulsion sample demonstrated a prolonged release of insulin within 48 hours of the experiment (43 %). Conclusions. As a result, the boundaries of the existence of microemulsion regions in pseudo-three — component systems water — polyglycerylpolyricinoleate / Tween 80 / ethanol — paraffin oil were established, as well as the values of the effective viscosity of a number of compositions were determined. The study of the kinetic and thermodynamic stability of the obtained systems, including those containing insulin, as well as the study of the kinetics of the release of biologically active substance from the microemulsion into the model medium, allowed us to determine the optimal composition for further development of nanoscale dosage forms intended for prolonged delivery of insulin to the gastrointestinal tract.

Vesicular Emulgel Based System for Transdermal Delivery of Insulin: Factorial Design and in Vivo Evaluation

Transdermal delivery of insulin is a great challenge due to its poor permeability through the skin. The aim of the current investigation was to evaluate the prospective of insulin loaded niosome emulgel as a noninvasive delivery system for its transdermal therapy. A 23 full-factorial design was used to optimize the insulin niosome emulgel by assessing the effect of independent variables (concentration of paraffin oil, Tween 80 and sodium carboxymethyl cellulose) on dependent variables (in vitro release, viscosity and in vitro permeation). The physical characteristics of the prepared formulations were carried out by determining viscosity, particle size, entrapment efficiency, drug loading, drug release and kinetics. In vitro permeation studies were carried out using rat skin membrane. Hypoglycemic activity of prepared formulations was assessed in diabetic-induced rats. It was observed that the independent variables influenced the dependent variables. A significant difference (p < 0.05) in viscosity was noticed between the prepared gels, which in turn influenced the insulin release. The order of permeation is: insulin niosome emulgel > insulin niosome gel > insulin emulgel > insulin gel > insulin niosomes > insulin solution. The enhancement in transdermal flux in insulin niosome emulgel was 10-fold higher than the control (insulin solution). In vivo data significantly demonstrated reduction (p < 0.05) of plasma glucose level (at six hours) by insulin niosome emulgel than other formulations tested. The results suggest that the developed insulin niosome emulgel could be an efficient carrier for the transdermal delivery of insulin.

“Oil-soluble” Reversed Lipid Nanoparticles for Oral Insulin Delivery

Background: In this study, we aimed to design a novel oral insulin delivery system, named “oil-soluble” reversed lipid nanoparticles (ORLN), in which a hydrophilic insulin molecule is encapsulated by a phospholipid (PC) shell and dissolved in oil to prevent the enzymatic degradation of insulin. ORLN was characterized by transmission electron microscopy and dynamic light scattering. Results: In vitro enzymatic stability studies showed higher concentrations of insulin in cells incubated with ORLN-encapsulated insulin than in those incubated with free insulin solution in artificial intestinal fluid (pH 6.5). The protective effect of ORLN was attributed to its special release behavior and the formulation of the PC shell and oil barrier. Furthermore, an in vivo oral efficacy study confirmed that blood glucose levels were markedly decreased after ORLN administration in both healthy and diabetic mice. In vivo pharmacokinetic results showed that the bioavailability of ORLN-conjugated insulin was approximately 28.7% relative to that of the group subcutaneously administered with an aqueous solution of insulin, indicating enhanced oral absorption.Conclusions: In summary, the ORLN system developed here shows promise as a nanocarrier for improving the oral absorption of insulin.

“Oil-soluble” Reversed Lipid Nanoparticles for Oral Insulin Delivery

Background In this study, we aimed to design a novel oral insulin delivery system, named “oil-soluble” reversed lipid nanoparticles (ORLN), in which a hydrophilic insulin molecule is encapsulated by a phospholipid (PC) shell and dissolved in oil to prevent the enzymatic degradation of insulin. ORLN was characterized by transmission electron microscopy and dynamic light scattering. Results In vitro enzymatic stability studies showed higher concentrations of insulin in cells incubated with ORLN-encapsulated insulin than in those incubated with free insulin solution in artificial intestinal fluid (pH 6.5). The protective effect of ORLN was attributed to its special release behavior and the formulation of the PC shell and oil barrier. Furthermore, an in vivo oral efficacy study confirmed that blood glucose levels were markedly decreased after ORLN administration in both healthy and diabetic mice. In vivo pharmacokinetic results showed that the bioavailability of ORLN-conjugated insulin was approximately 28.7% relative to that of the group subcutaneously administered with an aqueous solution of insulin, indicating enhanced oral absorption. Conclusions In summary, the ORLN system developed here shows promise as a nanocarrier for improving the oral absorption of insulin.

Mucin-Grafted Polyethylene Glycol Microparticles Enable Oral Insulin Delivery for Improving Diabetic Treatment

In this study, different ratios of mucin-grafted polyethylene-glycol-based microparticles were prepared and evaluated both in vitro and in vivo as carriers for the oral delivery of insulin. Characterization measurements showed that the insulin-loaded microparticles display irregular porosity and shape. The encapsulation efficiency and loading capacity of insulin were >82% and 18%, respectively. The release of insulin varied between 68% and 92% depending on the microparticle formulation. In particular, orally administered insulin-loaded microparticles resulted in a significant fall of blood glucose levels, as compared to insulin solution. Subcutaneous administration showed a faster, albeit not sustained, glucose fall within a short time as compared to the polymeric microparticle-based formulations. These results indicate the possible oral delivery of insulin using this combination of polymers.

Preparation of Nafion/Polycation Layer-by-Layer Films for Adsorption and Release of Insulin

Thin films were prepared using layer-by-layer (LbL) deposition of Nafion (NAF) and polycations such as poly(allylamine hydrochloride) (PAH), poly(ethyleneimine) (PEI), and poly(diallydimethylammonium chloride) (PDDA). Insulin was then adsorbed on the NAF-polycation LbL films by immersion in an insulin solution. The NAF-polycation LbL films were characterized using a quartz crystal microbalance and an atomic force microscope. The release of insulin from the LbL films was characterized using UV-visible adsorption spectroscopy and fluorescence emission spectroscopy. The greatest amount of insulin was adsorbed on the NAF-PAH LbL film. The amount of insulin adsorbed on the (NAF/PAH)5NAF LbL films by immersion in a 1 mg mL−1 insulin solution at pH 7.4 was 61.8 µg cm−2. The amount of insulin released from the LbL films was higher when immersed in insulin solutions at pH 2.0 and pH 9.0 than at pH 7.4. Therefore, NAF-polycations could be employed as insulin delivery LbL films under mild conditions and as an insulin release control system according to pH change.