Release behaviour of propranolol HCl from hydrophilic matrix tablets containing psyllium powder in combination with hydrophilic polymers

Drug release from magnesium aluminium silicate-polyethylene oxide (PEO) nanocomposite matrices: An investigation using the USP III apparatus

This work investigated the use of the USP III apparatus in discriminating simulated fed and fasted conditions as well as ionic strength on veegum-polyethylene (PEO) (called clay-PEO matrices hereafter) matrices. The successful formulations were characterised using differential scanning calorimetry (DSC) and evaluated for their physical properties. Isothermal calorimetry (ITC) was used to evaluate the thermodynamics of the complexation processes. The effect of agitation sequences on the matrices as evaluated from the USP III suggested an increase in polymer content to significantly decrease the burst release experienced using diltiazem hydrochloride (DILT) as a model cationic drug. The manufacturing methods showed superior performance in relation to a decrease in burst release over the physical manufactured counterparts. The clay-PEO matrices also showed robustness (no matrix failure) in up to 0.2 M ionic strength solutions mimicking the upper limit experienced in the GI tract. ITC results revealed that the binding between DILT and PEO was enthalpy and entropy-driven. Furthermore, the binding between veegum and DILT in the presence of PEO was shown to be enthalpy-driven and entropically unfavourable, which was also the case for the binding between veegum and PEO thus giving insights to how the matrices were performing on a molecular level.

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.

A molecular understanding of magnesium aluminium silicate - drug, drug - polymer, magnesium aluminium silicate - polymer nanocomposite complex interactions in modulating drug release: Towards zero order release

This study reports the use of ITC in understanding the thermodynamics occurring for a controlled release system in which complexation has been exploited. In this study, a model drug, propranolol hydrochloride (PPN) was complexed with magnesium aluminium silicate (MAS) and these complexes were used in combination with polyethylene oxide (PEO) as a hydrophilic carrier at various concentrations to sustain the release of PPN. DSC, XRPD, ATR-FTIR and SEM/EDX were successfully used in characterising the produced complexes. 2D- SAXS data patterns for MAS and the produced complexes were shown to be symmetric and circular with the particles showing no preferred orientation at the nanometre scale. ITC studies showed differences between PPN adsorption onto MAS compared with PPN adsorption onto a MAS-PEO mixture. At both temperatures studied the binding affinity K_a was greater for the titration of PPN into the MAS-PEO mixture (5.37E + 04 ± 7.54E + 03 M at 25 °C and 8.63E + 04 ± 6.11E + 03 M at 37 °C), compared to the affinity obtained upon binding between PPN and MAS as previously reported suggesting a stronger binding with implications for the dissolution process. MAS-PPN complexes with the PEO polymer compacts displayed desired manufacturing and formulation properties for a formulator including, reduced plastic recovery therefore potentially reducing the risk of cracking/splitting and on tooling wear, controlled release of PPN at a significantly low (5%) polymer level as well as a zero-order release profile (case II transport) using up to 50% polymer level.

Mechanical and release behaviour of theophylline from matrix tablets containing psyllium powder in combination with grewia polysaccharides

This study was aimed at investigating the effect of grewia polysaccharides on the mechanical and release properties of tablet matrices containing binary mixtures of the polysaccharide with psyllium. Two grades of grewia polysaccharides (GG and GDS) were extracted and binary mixtures of the polysaccharides with psyllium were formulated into tablet matrices containing theophylline as the model drug. The true, bulk and tapped densities, Carr's compressibility index of the powders and binary composites were determined before tablet compression. Tablet properties (hardness, porosity, and drug release from the matrices) were investigated. The dissolution test was carried out in 0.1 M HCl (pH 1.2) and phosphate buffer (pH 6.8). The results show that GG and GDS produced tablets with good mechanical strength (108.33 N and 95.70 N, respectively) while psyllium produced softer tablets (7.13 N). The combination of psyllium and grewia polysaccharides in the matrices resulted in a significant increase in the mechanical strength of the matrices when compared to matrices containing psyllium alone as the matrix former. The results also showed that GG and GDS reduced the dissolution rate and effectively eliminated the burst release of theophylline from the psyllium matrices at both pHs. The matrices of GG or GDS and the binary mixtures conform to non-Fickian anomalous diffusion with n > 0.45. When overcoming the burst release of drug from matrices such as psyllium, grewia polysaccharides may provide an effective reduction and a more sustained drug release from such matrices.

3D printing of responsive hydrogels for drug-delivery systems

3D printing technology has enabled unprecedented flexibility in the design and manufacturing of complex objects, which can be utilized in personalized and programmable medicine. The aim of this study is to evaluate the potential of 3D printing by digital light processing to fabricate drug-loaded systems with special designs and unique drug-release characteristics, which otherwise are not possible to fabricate by conventional pharmaceutical manufacturing methods. Oral dosage forms of pH responsive hydrogels were 3D printed using acrylic acid monomer, cross-linker (polyethylene glycol diacrylate) and photoinitiator (2,4,6-trimethylbenzoyl-diphenylphosphine oxide [TPO] nanoparticles). Sulforhodamine B, a pH independent fluorescent dye, was used to model a small molecule hydrophilic drug. The printed structures exhibited pH responsive swelling and the effect of pH and tablets’ surface area were studied on drug release. The tablets showed higher swelling and faster drug release at higher pH, making them a promising system for enhancing drug absorption in the intestine. Structures with large surface area and complex structures showed enhanced swelling and faster drug release and vice versa.

The influence of hydroalcoholic media on the performance of Grewia polysaccharide in sustained release tablets

Co-administration of drugs with alcohol can affect the plasma concentration of drugs in patients. It is also known that the excipients used in the formulation of drugs may not always be resistant to alcohol. This study evaluates effect of varying alcohol concentrations on theophylline release from two grades of Grewia mollis polysaccharides. X-ray microtomography showed that native polysaccharide formulation compacts were not homogenous after the mixing process resulting in its failure in swelling studies. Removal of starch from the native polysaccharide resulted in homogenous formulation compacts resistant to damage in high alcoholic media in pH 6.8 (40%v/v absolute ethanol). Destarched polymer compacts had a significantly higher hardness (375N) than that of the native polysaccharide (82N) and HPMC K4M (146N). Dissolution studies showed similarity at all levels of alcohol tested (f₂=57-91) in simulated gastric media (pH 1.2). The dissolution profiles in the simulated intestinal fluids were also similar (f₂=60-94), with the exception of the native polysaccharide in pH 6.8 (40%v/v absolute ethanol) (f₂=43). This work highlights the properties of Grewia polysaccharide as a matrix former that can resist high alcoholic effects therefore; it may be suitable as an alternative to some of the commercially available matrix formers with wider applications for drug delivery as a cheaper alternative in the developing world.

Ex-vivoand in-vitro assessment of mucoadhesive patches containing the gel-forming polysaccharide psyllium for buccal delivery of chlorhexidine base

The aim of the present study was to evaluate the gel-forming polysaccharide psyllium in the preparation of mucoadhesive patches for the controlled release of chlorhexidine (CHX) to treat pathologies in the oral cavity, using the casting-solvent evaporation technique. A number of different film-forming semi-synthetic polymers, such as sodium carboxymethyl cellulose (SCMC) and hydroxypropylmethyl cellulose (HPMC) were evaluated for comparison. The patch formulations were characterized in terms of drug content, morphology surface, swelling and mucoadhesive properties, microbiology inhibition assay and in vitro release tests. Three ex-vivo testswere carried out using porcine mucosa: an alternative dissolution test using artificial saliva that allows contemporary measurement of dissolution and mucoadhesion, a permeation test through the mucosa and the measurement of mucoadhesion using a Nouy tensile tester, as the maximum force required for the separation of the patch from the mucosa surface. The patches were also examined for determination of the minimum inhibitory concentration in cultures of Escherichia coli and Staphylococcus aureus. All the patches incorporating psyllium were found suitable in terms of external morphology, mucoadhesion and controlled release of the drug: in the presence of psyllium the drug displays prolonged zero-order release related to slower swelling rate of the system.

Intranasal and intravenous administration of octa-arginine modified poly(lactic-co-glycolic acid) nanoparticles facilitates central nervous system delivery of loperamide

Objectives

The potential of poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) surface modified with octa-arginine (R8) for central nervous system (CNS) delivery was investigated.

Methods

PLGA NPs containing coumarin-6 or loperamide were surface modified using R8 and characterised for size, zeta potential, drug loading and release. We examined the cellular uptake of NPs in Madin-Darby Canine Kidney (MDCK) cells and CNS delivery of loperamide in a mouse model following intranasal (i.n.) and intravenous (i.v.) administration.

Key findings

NPs were 300–350 nm in diameter and of negative zeta potential which neutralised on R8 conjugation. Cellular uptake of R8-PLGA NPs was rapid compared with PLGA NPs and correlated with a high antinociceptive effect in mice by both the i.n. and i.v. routes. Little antinociceptive effect for PLGA NPs was observed reflecting their slow uptake in the in-vitro cell model.

Conclusion

This study demonstrates the potential of R8-PLGA NPs as carriers of therapeutic agents to the CNS.

Comparative evaluation of the degree of pegylation of poly(lactic-co-glycolic acid) nanoparticles in enhancing central nervous system delivery of loperamide

Objectives

In this study, we examined the relative cellular uptake of nanoparticles (NPs) formulated using poly(lactic-co-glycolic acid) (PLGA) polymers with increasing degree of pegylation (PLGA-PEG) and their potential to deliver loperamide to the brain of a mouse.

Method

NPs containing coumarin-6 or loperamide HCl were formulated using PLGA and PLGA-PEG, with PEG content of 5–15%, by the solvent evaporation method. NPs were characterised for size, surface charge, morphology, encapsulation efficiency and drug release. Cellular uptake of coumarin-6 NPs was examined in Caco-2 monolayers using confocal microscopy and central nervous system (CNS) delivery of loperamide HCl from the NPs was examined following intranasal administration in a mouse model.

Key findings

No difference in NP characteristics was observed, irrespective of degree of pegylation, except for the surface charge which increased with increasing PEG content. PLGA-PEG NPs were found to have increased cellular uptake in comparison to PLGA NPs. Interestingly, this pattern was reflected in the CNS delivery of loperamide HCl in the mouse model.

Conclusion

The results from this study show that PLGA-PEG NPs have the potential to act as carriers for the noninvasive administration of therapeutic agents to the brain and possibly across other physiological barriers.

The role of oral controlled release matrix tablets in drug delivery systems

Formulations that are able to control the release of drug have become an integral part of the pharmaceutical industry. In particular oral drug delivery has been the focus of pharmaceutical research for many years. This type of drug delivery has been at the centre of research due to its many benefits over conventional dosage. The focus of this review is on matrix tablets due to their widely use and simplicity of the formulation. This includes the discussion of various types of matrix tablets and factors affecting the drug release from these formulations. The mechanism of drug release from HPMC matrices is also discussed.