Regenerated cellulose capsules for controlled drug delivery: Part IV. In-vitro evaluation of novel self-pore forming regenerated cellulose capsules

Fabrication of delayed release hard capsule shells from zein/methacrylic acid copolymer blends

Hard capsule shells with an inherent delayed release action are useful for oral administration of active ingredients, which are acid-labile and/or enzymatically degradable in the gastric environment, without the need of film coating. The objective of this study was to fabricate delayed release hard capsule shells by the dip coating method. The film coating formulations comprised blends of zein and methacrylic acid copolymer (Eudragit® L100-55), with and without the addition of the plasticizer, polyethylene glycol 1000. The rheology parameters (loss modulus (G'), storage modulus (G") and loss tangent (tan δ, G"/G')) of the film coating solution were measured to investigate the processability. Central composite design was used to investigate the main, interaction and quadratic effects of the proportion of methacrylic acid copolymer, solid content of the film formers and level of polyethylene glycol 1000 on the capsule wall thickness and mechanical strength. Multiple response optimization was further conducted, and the design space was established. The in vitro drug release in simulated gastric and intestinal fluids of three different formulations in the design space was compared. The results showed that the tan δ value after the gelation point should be < 0.9 in order to form a thin and sturdy capsule shell. The gelation time and viscosity of the coating solution were related to the thickness of the capsule shell. The study showed that drug release from the capsule with a specified thickness and mechanical strength can be modulated by varying the ratio of zein to methacrylic acid copolymer. The delayed drug release profile was achieved through the capsule shell fabricated from zein to methacrylic acid copolymer at the ratios of 75:25 and 83.2:16.8, with 10% polyethylene glycol 1000.

Visualized analysis and evaluation of simultaneous controlled release of metformin hydrochloride and gliclazide from sandwiched osmotic pump capsule

The aim of this study was to develop the Metformin Hydrochloride and Gliclazide (MH-GZ) sandwiched osmotic pump capsule which could overcome the problems associated with short half-life and burst release. The system could deliver drugs with different solubility simultaneously at zero-order rate, in which MH-GZ were filled in both sides of the push layer respectively. The single factor and orthogonal test were employed to obtain the optimized formulation with the evaluation index of similarity factor (ƒ₂). R language was used to visualized analyze the main influence factors of drug release and their correlations. Pharmacokinetic study was performed in beagle dogs compared to the marketed conventional product, which showed decreased C_max, prolonged T_max, and improved bioavailability, independent of pH and agitational speed but related to osmotic pressure differences across the semi permeable membrane. The designed sandwiched osmotic pump capsule proposed a promising substitute for the marketed product for the treatment of type 2 diabetes.

Comparisons of in vitro Fick's first law, lipolysis, and in vivo rat models for oral absorption on BCS II drugs in SNEDDS

Purpose

The objective of this study was to compare the in vitro Fick’s first law, in vitro lipolysis, and in vivo rat assays for oral absorption of Biopharmaceutical Classification Systems Class II (BCS II) drugs in self-nanoemulsifying drug delivery system (SNEDDS), and studied drugs and oils properties effects on the absorption.

Methods

The transport abilities of griseofulvin (GRI), phenytoin (PHE), indomethacin (IND), and ketoprofen (KET) in saturated water solutions and SNEDDS were investigated using the in vitro Madin-Darby canine kidney cell model. GRI and cinnarizine (CIN) in medium-chain triglycerides (MCT)-SNEDDS and long-chain triglycerides (LCT)-SNEDDS were administered in the in vivo SD rat and in vitro lipolysis models to compare the oral absorption and the distribution behaviors in GIT and build an in vitro-in vivo correlation (IVIVC).

Results

In the cell model, the solubility of GRI, PHE, IND, and KET increased 6–8 fold by SNEDDS, but their permeability were only 18%, 4%, 8%, and 33% of those of their saturated water solutions, respectively. However, in vivo absorption of GRI-SNEDDS was twice that of the GRI suspension and those of CIN-SNEDDS were 15–21 fold those of the CIN suspension. In the lipolysis model, the GRI% in aqueous and pellet phases of MCT were similar to that in LCT. In contrast, the CIN% in the aqueous and pellet phases were decreased but that of the lipid phase increased. In addition, an IVIVC was found between the CIN% in the lipid phase and in vivo relative oral bioavailability (F_r).

Conclusion

The in vitro cell model was still a suitable tool to study drug properties effects on biofilm transport and SNEDDS absorption mechanisms. The in vitro lipolysis model provided superior oral absorption simulation of SNEDDS and helped to build correlation with in vivo rats. The oral drug absorption was affected by drug and oil properties in SNEDDS.

Polymer Distribution and Mechanism Conversion in Multiple Media of Phase-Separated Controlled-Release Film-Coating

Phase-separated films of water-insoluble ethyl cellulose (EC) and water-soluble hydroxypropyl cellulose (HPC) can be utilized to tailor drug release from coated pellets. In the present study, the effects of HPC levels and the pH, type, ionic strength and osmolarity of the media on the release profiles of soluble metoprolol succinates from the EC/HPC-coated pellets were investigated, and the differences in drug-release kinetics in multiple media were further elucidated through the HPC leaching and swelling kinetics of the pellets, morphology (SEM) and water uptake of the free films and the interaction between the coating polymers and the media compositions. Interestingly, the drug release rate from the pellets in different media was not in agreement with the drug solubility which have a positive correlation with the drug dissolution rate based on Noyes–Whitney equation law. In particular, the drug release rate in acetate buffer at pH 4.5 was faster than that in other media despite the solubility of drug was relatively lower, regardless of the HPC levels. It may be attributed to the mutual effect between the EC and acetate buffer, which improved the permeability of the film. In contrast, the release of drug in HCl solution was dependent on the HPC levels. Increasing the levels of HPC increased the effects of hydrogen ions on the polymer of HPC, which resulted in a lower viscosity and strength of the gel, forming the larger size of pores in polymer films, thus increasing the drug diffused from the coating film. Further findings in phosphate buffer showed a reduction in the drug release compared to that in other media, which was only sensitive to the osmolarity rather than the HPC level and pH of the buffer. Additionally, a mathematical theory was used to better explain and understand the experimentally measured different drug release patterns. In summary, the study revealed that the effects of the media overcompensated that of the drug solubility to some extent for controlled-release of the coating polymers, and the drug release mechanism in multiple media depend on EC and HPC rather than on HPC alone, which may have a potential to facilitate the optimization of ideally film-coated formulations.

A Novel Colon-Specific Osmotic Pump Capsule of Panax notoginseng Saponins (PNS): Formulation, Optimization, and In Vitro-In Vivo Evaluation

In the current study, a novel colon-specific osmotic pump capsule of Panax notoginseng saponins was developed to achieve colon-specific release, a zero-order, thus to promote the efficacy of Panax notoginseng saponins. The capsule was assembled using a semi-permeable capsule shell with contents including Panax notoginseng saponins, sodium chloride (NaCl), and Ludipress. The semipermeable membrane was made of cellulose acetate (CA), along with polyethylene glycol (PEG) 6000 for flexibility and strength, and Eudragit® S100 for colon-specific targeting. The in vitro dissolution test showed an approximately zero-order release of Panax notoginseng saponins over 12 h at pH 7.8 through the pores on the membrane. Meanwhile, the drug release from the optimal formulation was found to be independent of equipment type or agitation speed. Rather, it depended on mainly the osmotic pressure of the dissolution media. The in vivo test in beagle dogs demonstrated that the relative bioavailability of the current system was 487.42% in comparison to that of the marketed product, yet with a prolonged retention time. The novel controlled delivery system for Panax notoginseng saponins in the current study utilizing colon-specific and osmotic pump system therefore offered the advantages of avoiding stomach and enteric irritation, reducing dosage frequency, minimizing the drug fluctuation in plasma, and improving its oral bioavailability.