Assessment of hydrophobic-ion paired insulin incorporated SMEDDS for the treatment of diabetes mellitus

Comparative Analysis of PEG-Free and PEG-Based Self-Emulsifying Drug Delivery Systems for Enhanced Oral Bioavailability of Therapeutic (Poly) Peptides

This study aims to compare the potential of Polyethylene glycol (PEG-free and PEG-based self-emulsifying drug delivery systems (SEDDS) for the oral administration of insulin glargine (IG). Hydrophobic ion pairs (HIPs) of IG are formed using various counterions. HIPs are assessed for log P octanol/water and dissociation behavior. They are incorporated into SEDDS based on polyglycerol (PG) and zwitterionic surfactant (ZW) using response surface methodology and compared to conventional PEG-SEDDS in size, stability, and log D SEDDS/release medium . Oral IG bioavailability in PG/ZW-SEDDS and PEG-SEDDS is evaluated in rats. Among the various counterions studied, IG-BIS (bis(isotridecyl)sulfosuccinate) HIPs demonstrated the highest log P and an improved dissociation profile. PG/ZW-SEDDS and PEG-SEDDS have similar ≈40 nm sizes and are stable over 24 h. Both formulations have log D > 4 in water and >2 in 50 mM phosphate buffer pH 6.8. PG/ZW-SEDDS yielded an oral bioavailability of 2.13 ± 0.66% for IG, while the employment of PEG-SEDDS resulted in an oral bioavailability of 1.15 ± 0.35%. This study highlights the prospective utilization of PEG-free SEDDS involving the concurrent application of PG and ZW surfactants, an alternative to conventional PEG surfactants, for improved oral therapeutic (poly) peptide delivery.

Design and Evaluation of Hydrophobic Ion Paired Insulin Loaded Self Micro-Emulsifying Drug Delivery System for Oral Delivery

Despite several novel and innovative approaches, clinical translation of oral insulin delivery into commercially viable treatment is still challenging due to its poor absorption and rapid degradation in GIT. Thus, an insulin-SDS hydrophobic ion pair loaded self-microemulsifying drug delivery system (SMEDDS) was formulated to exploit the hypoglycemic effects of orally delivered insulin. Insulin was initially hydrophobically ion paired with sodium dodecyl sulphate (SDS) to enhance its lipophilicity. The successful complexation of Insulin-SDS was confirmed by FTIR and surface morphology was evaluated using SEM. Stability of insulin after its release from HIP complex was evaluated using SDS PAGE. Subsequently, Ins-SDS loaded SMEDDS was optimized using two factorial designs. In vitro stability of insulin entrapped in optimized SMEDDS against proteolytic degradation was also assessed. Further, antidiabetic activity of optimized Ins-SDS loaded SMEDDS was evaluated in diabetic rats. Insulin complexed with SDS at 6:1 (SDS/insulin) molar ratio with almost five-fold increased lipophilicity. The SMEDDS was optimized at 10% Labraphil M2125 CS, 70% Cremophore EL, and 20% Transcutol HP with better proteolytic stability and oral antidiabetic activity. An Ins-SDS loaded SMEDDS was successfully optimized. Compared with insulin and Ins-SDS complex, the optimized SMEDDS displayed considerable resistance to GI enzymes. Thus, the SMEDDS showed potential for effective delivery of macromolecular drugs with improved oral bioavailability.

Self-emulsifying drug delivery systems (SEDDS): In vivo-proof of concept for oral delivery of insulin glargine

In spite of recent progress made in the field of peptide and protein delivery, oral administration of insulin and similar drugs remains a challenge. In this study, lipophilicity of insulin glargine (IG) was successfully increased via hydrophobic ion pairing (HIP) with sodium octadecyl sulfate to enable incorporation into self-emulsifying drug delivery systems (SEDDS). Two SEDDS formulations (F1: 20% Labrasol®ALF, 30% polysorbate 80, 10% Croduret 50, 20% oleyl alcohol, 20% Maisine® CC; F2: 30% Labrasol®ALF, 20% polysorbate 80, 30% Kolliphor® HS 15, 20% Plurol® oleique CC 497) were developed and loaded with the IG-HIP complex. Further experiments confirmed increased lipophilicity of the complex, achieving Log D_{SEDDS/release medium} values of 2.5 (F1) and 2.4 (F2) and ensuring sufficient amounts of IG within the droplets after dilution. Toxicological assays indicated minor toxicity and no toxicity inherent to the incorporated IG-HIP complex. SEDDS formulations F1 and F2 were administered to rats via oral gavage and resulted in a bioavailability of 0.55% and 0.44%, corresponding to a 7.7-fold and 6.2-fold increased bioavailability, respectively. Thus, incorporation of complexed insulin glargine into SEDDS formulations provides a promising approach to facilitate its oral absorption.