Carboxylated high amylose starch as pharmaceutical excipients. Structural insights and formulation of pancreatic enzymes

Effect of microwave alone and microwave-assisted modification on the physicochemical properties of starch and its application in food

Native starch has poor stability and usually requires modification to expand its industrial application range. Commonly used methods are physical, chemical, enzymatic and compound modification. Microwave radiation, as a kind of physical method, is promising due to its uniform energy radiation, greenness, safety, non-toxicity. It can meet the demand of consumers for safe food. Microwave-assisted modification with other methods can directly or indirectly affect the structure of starch granules to obtain modified starch with high degree of substitution and low viscosity, and the modification efficiency is greatly improved. This paper reviews the effect of microwave radiation on the physicochemical properties of starch, such as granule morphology, crystallization characteristics, and gelatinization characteristics, as well as the application of microwave radiation in starch modification and starch food processing. It provides theoretical references and suggestions for the research of microwave heating modified starch and the deep processing of starchy foods.

Guava fibre characterization and effects on digestibility, fermentation products, gastrointestinal transit time and palatability of dry diets for dogs

The use of fruit fibres as a way of reusing industrial waste is attractive and necessary, increasing the efficiency and reducing the environmental impact of the industry. This study characterized guava fibre as a fibrous ingredient and evaluated its effects when included in extruded diets for dogs on nutrient digestibility, faecal traits, fermentation products, gastrointestinal transit time and palatability. Four diets were formulated: CO (control diet, no fibrous ingredients added), GF3 (3% guava fibre), GF6 (6% guava fibre) and GF12 (12% guava fibre). The guava fibre was added to diets in replacement of maize, with small adjustments in the other ingredients to ensure similar contents of protein and fat. The diets were fed to 24 adult Beagle dogs (6 per diet) during 15 days for adaptation followed by 15 days for assessment of digestibility, fermentation end products and gastrointestinal transit time. The palatability of G6 and G12 treatments was evaluated against the CO by the two-pan test. Results were compared by analysis of variance and polynomial contrasts according to the guava fibre inclusion level (p < 0.05). The addition of guava fibre did not change nutrient intake except for the increase on dietary fibre (p < 0.001). Fibre inclusion resulted in a quadratic reduction in total tract apparent digestibility for dry matter, organic matter, crude protein and crude energy (p < 0.001), and on the metabolizable energy content of the foods (p < 0.001). Guava fibre addition did not change the faecal concentration of ammonia, lactic acid, faecal pH and branched chain fatty acids but it decreased acetic and propionic acids concentration (p < 0.01). The inclusion of 12% guava fibre did result in a faster transit time (p = 0.046) compared to the control diet. Guava fibre can be characterized as a novel insoluble non-fermentable fibre source that could be safely used in levels up to 12% in canine extruded diets.

Carboxymethyl Starch Films as Enteric Coatings: Processing and Mechanistic Insights

This study proposes the application of carboxymethyl starch derivatives as tablet coatings affording gastro-protection. Carboxymethyl starch (CMS) films were obtained by casting of aqueous filmogenic starch solutions with or without plasticizers and their structural organization was followed using Fourier transform infrared (FTIR), Thermogravimetric analysis (TGA), X-ray diffraction (XRD). Together with data from mechanical tests (tensile strength, elongation, Young's modulus) the results were used to select filmogenic formulations adapted for coatings of tablets. The behaviour of these films was evaluated in simulated gastric and intestinal fluids. The effect of plasticizers (glycerol and sorbitol) on the starch organization, on the rate of drying of the films and on the water vapor absorption was also analyzed. Various types of starch have been compared and the best results were found with high amylose starch (HAS) that was carboxymethylated in an aqueous phase to obtain carboxymethyl high amylose starch (CMHAS). The CMHAS coating solutions containing sorbitol or glycerol as plasticizers have been applied with an industrial pan coater and the final tablets exhibited a good gastro-resistance (up to 2h) in simulated gastric fluid followed by disintegration in simulated intestinal fluid (SIF). The CMHAS derivatives present a high potential as coatings for nutraceutical and pharmaceutical solid dosage forms.

Hydrolysis effects on the water uptake of starch-g-glycidyl methacrylate (GMASt)/dimethylacrylamide (DMAAm)-based hydrogels for potential agricultural purposes

This work assessed the effect of different hydrolysis periods on the properties of hydrogels based on 75 % w w-1 of N,N'-dimethyl acrylamide (DMAAm) and 25 % w w-1 of starch-g-(glycidyl methacrylate) (GMASt). FTIR results confirmed the conversion of ester groups into carboxylic acids and carboxylates, besides forming a keto-enol tautomer due to the peeling reaction of starch. For DMAAm, the hydrolysis mostly converted amide into carboxylate groups. The morphology, thermal stability, and the mechanical properties of the predominantly amorphous matrices (as confirmed by XRD results) did not drastically change even after 10 days of hydrolysis in alkali media. However, the thermogravimetric analysis results suggested that DMAAm partially protected GMASt from the hydrolysis. The swelling degree of the matrix increased from (10.1 ± 2.1) g g-1 to (61.9 ± 2.6) g g-1 after 1 day of hydrolysis, but no statistical differences (at 95 % of significance) were observed for the matrices hydrolyzed for longer periods, confirming that the maximum hydrolysis occurred within 24 h. The results confirmed that the hydrolysis increased the water uptake of the GMASt/DMAAm-based matrices, making appealing for uses as a water retentor for agricultural purposes.

Anionic and Ampholytic High-Amylose Starch Derivatives as Excipients for Pharmaceutical and Biopharmaceutical Applications: Structure-Properties Correlations

Many chemical modifications of starch are realized in organic (mostly methanol) phase, allowing high degrees of substitution (DS). Some of these materials are used as disintegrants. To expand the usage of starch derivative biopolymers as drug delivery system, various starch derivatives obtained in aqueous phase were evaluated with the aim to identify materials and procedures which would generate multifunctional excipients providing gastro-protection for controlled drug delivery. Chemical, structural and thermal characteristics of anionic and ampholytic High Amylose Starch (HAS) derivatives under powder (P), tablet (T) and film (F) forms were evaluated by X-ray Diffraction (XRD), Fourier Transformed Infrared (FTIR) and thermogravimetric analysis (TGA) methods and correlated with the behavior of tablets and films in simulated gastric and intestinal media. At low DS, the HAS carboxymethylation (CMHAS) in aqueous phase, generated tablets and films that were insoluble at ambient conditions. The CMHAS filmogenic solutions, with a lower viscosity, were easier to cast and gave smooth films without the use of plasticizer. Correlations were found between structural parameters and the properties of starch excipients. Compared to other starch modification procedures, the aqueous modification of HAS generated tunable multifunctional excipients that may be recommended for tablets and functional coatings for colon-targeted formulations.

Antibacterial quaternary ammonium chitosan/carboxymethyl starch/alginate sponges with enhanced hemostatic property for the prevention of dry socket

Tooth extraction commonly leads to postoperative wound bleeding, bacterial infection, and even the occurrence of dry socket. Therefore, developing a biomedical material with favorable antibacterial and excellent hemostatic properties to prevent the post-extraction dry socket is necessary. Herein, quaternary ammonium chitosan/ carboxymethyl starch/alginate (ACQ) sponges are developed via Ca²⁺ cross-linking, electrostatic interaction, and lyophilization methods. The results show that the bio-multifunctional sponges exhibit interconnected porous structures with significant fluid absorption rates and suitable water vapor transmission rates. In vitro cellular and hemolysis experiments indicate that the developed sponges have acceptable biocompatibility. Notably, the constructed sponges effectively inhibit the growth of E. coli, S. aureus, and C. albicans, as well as achieve rapid hemostasis in the mouse liver injury and mini-pig tooth extraction models by absorbing blood and promoting red blood cell adhesion. Thus, the created bio-multifunctional sponges show tremendous promise as a hemostatic material for wound management after tooth extraction.

Review of the Most Important Methods of Improving the Processing Properties of Starch toward Non-Food Applications

Starch is the second most abundantly available natural polymer in the world, after cellulose. If we add its biodegradability and non-toxicity to the natural environment, it becomes a raw material very attractive for the food and non-food industries. However, in the latter case, mainly due to the high hydrophilicity of starch, it is necessary to carry out many more or less complex operations and processes. One of the fastest growing industries in the last decade is the processing of biodegradable materials for packaging purposes. This is mainly due to awareness of producers and consumers about the dangers of unlimited production and the use of non-degradable petroleum polymers. Therefore, in the present review, an attempt was made to show the possibilities and limitations of using starch as a packaging material. The most important physicochemical features of this biopolymer are discussed, and special attention is paid to more or less environmentally friendly methods of improving its processing properties.

In vivo evaluation of targeted delivery of biological agents using barium sulfate

This study was aimed to monitor the transit through the intestine by X-ray imaging using barium sulfate (BS) as tracer. The in vitro features of monolithic tablets were correlated with their in vivo behavior in order to provide a tool for the development of targeted formulations containing macromolecular bioactive agents. The impact of BS on various matrices (neutral, ionic) was studied in simulated fluids using the disintegration time (DT) as main parameter. Dry tablets were characterized by spectroscopic methods (X-ray diffraction and Infra-Red) and scanning electron microscopy (SEM). The selected formulations were followed in a beagle dog model. The in vivo and in vitro DT of tablets formulated with BS were compared. Results: anionic excipients carboxymethylcellulose (CMC) and carboxymethylstarch (CMS) protected the active ingredient from the gastric acidity, ensuring its targeted delivery in the intestine. The SEM analysis, before and after transit in simulated fluids, showed that BS remained in the tablets allowing their good follow-up in vivo. The incorporation of 30% protein in tablets with 40% BS had no impact on their behavior. In conclusion, BS and X-ray imagery could be a good alternative to scintigraphy for development of targeted formulations containing high molecular weight bioactive agents.

Ampholytic and Polyelectrolytic Starch as Matrices for Controlled Drug Delivery

The potential of the polyampholytic and polyelectrolytic starch compounds as excipients for drug controlled release was investigated using various tracers differing in terms of solubility and permeability. Ampholytic trimethylaminecarboxymethylstarch (TMACMS) simultaneously carrying trimethylaminehydroxypropyl (TMA) cationic groups and carboxymethyl (CM) anionic groups was obtained in one-step synthesis in aqueous media. Trimethylaminestarch (TMAS) and carboxymethylstarch (CMS) powders were also synthesized separately and then homogenized at equal proportions in liquid phase for co-processing by spray drying (SD) to obtain polyelectrolytic complexes TMAS-CMS (SD). Similarly, equal amounts of TMAS and CMS powders were dry mixed (DM) to obtain TMAS:CMS (DM). Monolithic tablets were obtained by direct compression of excipient/API mixes with 60% or 80% drug loads. The in vitro dissolution tests showed that ampholytic (TMACMS) and co-processed TMAS-CMS (SD) with selected tracers (one from each class of Biopharmaceutical Classification System (BCS)), were able to control the release even at very high loading (80%). The presence of opposite charges located at adequate distances may impact the polymeric chain organisation, their self-assembling, and implicitly the control of drug release. In conclusion, irrespective of preparation procedure, ampholytic and polyelectrolytic starch materials exhibited similar behaviours. Electrostatic interactions generated polymeric matrices conferring good mechanical features of tablets even at high drug loading.

Polyelectrolyte Complexation versus Ionotropic Gelation for Chitosan-Based Hydrogels with Carboxymethylcellulose, Carboxymethyl Starch, and Alginic Acid

The preparation of gels by charge interaction methods has been extensively studied, but it is not yet clear how these methods influence gel characteristics. The objective of this work was to study differences in morphology and surface charge of hydrogels prepared by ionotropic gelation, polyelectrolyte complexation, and a combination of both methods. Thus, the anionic charge was provided by carboxymethylcellulose (CMC), carboxymethylated starch (CMS), and alginic acid (AA); calcium chloride (CaCl2) and chitosan (CS) were used for the ionotropic gelation and polyelectrolyte complexation, respectively. Those materials are commercially available, have low toxicity, and are widely used in the area. These compounds interact through physical crosslinks, which are affected by physical changes of the medium. Our results showed that these two methods produced changes in the morphology of the hydrogels. CMC gels exhibited larger pores in the presence of CaCl2. In polyelectrolyte complexation, CMS produced an increased agglomeration of particles, while the addition of CaCl2 to AA generated dispersed particles of size in the order of millimeters. Mixing both ionotropic gelation and polyelectrolyte complexation methods yielded gels of varied charge (568 mV for CMC, 502 mV for CMS, and 1713 mV for AA). FTIR spectra of the hydrogels showed interactions between the different polymeric compounds, being the greatest changes between 1250 and 1600 cm−1, due possibly to the replacement of Na by Ca at crosslinking points. Therefore, the method of gel preparation employed had a major influence on the size and pore distribution, parameters which in turn influence encapsulation and drug delivery in these systems.

Evaluation of absorbable hemostatic agents of polyelectrolyte complexes using carboxymethyl starch and chitosan oligosaccharide both in vitro and in vivo

CMS/COS PECs with a suitable COS content were promising absorbable hemostatic agents for internal use.

Carboxymethyl Starch Excipients for Drug Chronodelivery

Carboxymethyl starch (CMS) is a pH-responsive excipient exhibiting also interesting properties for applications in delayed drug delivery systems. This work was aimed to investigate the release properties of monolithic and dry-coated tablets based on ionic sodium CMS and on protonated CMS, formulated with three model tracers: acetaminophen, acetylsalicylic acid (ASA), and sodium diclofenac. The sodium or protonated CMS were obtained from the same CMS synthesis by controlling the final pH of reaction media. The two forms of CMS were confirmed by the Fourier transform infrared spectroscopy. The in vitro dissolution profiles for monolithic and double core tablets were different and allowed a better understanding of characteristics of the two excipient forms. It was found that the protonated CMS exhibited a better stability in simulated gastric fluid in comparison to its sodium salt in monolithic dosage forms, whereas both excipients afforded a complete gastric protection of drugs when formulated as dry-coated dosages. Determination of water uptake and erosion rate of monolithic matrices based on the two CMS forms showed different mechanisms involved in the delivery of the three model active molecules in simulated intestinal media. When pancreatic enzymes were added in dissolution media, the drug release was accelerated showing that CMS is still a substrate for alpha-amylase. Both sodium and protonated starch excipients, formulated as dry-coated dosages, afforded a good gastro-protection and allowed a drug chronodelivery at various intervals up to 4-5 h. They could be considered as an alternative for delayed delivery and a solvent-free coating procedure.

Starch materials as biocompatible supports and procedure for fast separation of macrophages

Different starch derivatives were evaluated as supports for attachment and recovery of macrophages (RAW 264.7 line). Gelatinized starch (G-St), acetate starch (Ac-St), carboxymethyl starch and aminoethyl starch were synthesized and characterized by FTIR, ¹H NMR, SEM and static water contact angle. These polymers are filmogenic and may coat well the holder devices used for macrophage adhesion. They also present a susceptibility to mild hydrolysis with alpha-amylase, liberating the adhered macrophages. Cell counts, percentage of dead cells and level of tumor necrosis factor (TNF-α) were used to evaluate the possible interaction between macrophages and starch films. The high percentage of cell adhesion (90-95% on G-St and on Ac-St) associated with enzymatic detachment of macrophages from film-coated inserts, resulted in higher viabilities compared with those obtained with cells detached by current methods scrapping or vortex. This novel method allows a fast macrophage separation, with excellent yields and high viability of recovered cells.

Synthesis and evaluation of the structural and physicochemical properties of carboxymethyl pregelatinized starch as a pharmaceutical excipient

A pregelatinized starch (PGS) was derivatized with sodium chloroacetate (SCA) in alcoholic medium under alkaline condition to produce carboxymethyl pregelatinized starch (CMPGS) with various degrees of substitution (DS). Influence of the molar ratio of SCA to the glucopyranose units (SCA/GU), reaction time, temperature and the amount of sodium hydroxide on the degree of substitution (DS) and the reaction efficiency (RE) was studied. An optimal concentration of 30% of NaOH, for a reaction time of 1 h at 50 °C and molar ratio (SCA/GU) equal to 1.0, yielded an optimal DS of 0.55 and a RE of 55%. SEM micrographs revealed that the carboxymethylation assigned the structural arrangement of CMPGS and caused the granular disintegration. Wide angle diffraction X-ray (XRD) showed that the crystallinity of starch was obviously varied after carboxymethylation. New bands in FTIR spectra at 1417 and 1603 cm(-1) indicated the presence of carboxymethyl groups. The solubility and viscosity of CMPGS increased with an increase in the degree of modification. In order to investigate the influence of DS on physical and drug release properties, CMPGS obtained with DS in the range of 0.12-0.55 was evaluated as tablet excipient for sustained drug release. Dissolution tests performed in phosphate buffer (pH 6.8), with Ibuprofen as drug model (25% loading) showed that CMPGS seems suitable to be used as sustained release excipient since the drug release was driven over a period up to 8 h. The in vitro release kinetics studies revealed that all formulations fit well with Korsmeyer-Peppas model and the mechanism of drug release is non-Fickian diffusion.

High-amylose sodium carboxymethyl starch matrices: development and characterization of tramadol hydrochloride sustained-release tablets for oral administration

Substituted amylose (SA) polymers were produced from high-amylose corn starch by etherification of its hydroxyl groups with chloroacetate. Amorphous high-amylose sodium carboxymethyl starch (HASCA), the resulting SA polymer, was spray-dried to obtain an excipient (SD HASCA) with optimal binding and sustained-release (SR) properties. Tablets containing different percentages of SD HASCA and tramadol hydrochloride were produced by direct compression and evaluated for dissolution. Once-daily and twice-daily SD HASCA tablets containing two common dosages of tramadol hydrochloride (100 mg and 200 mg), a freely water-soluble drug, were successfully developed. These SR formulations presented high crushing forces, which facilitate further tablet processing and handling. When exposed to both a pH gradient simulating the pH variations through the gastrointestinal tract and a 40% ethanol medium, a very rigid gel formed progressively at the surface of the tablets providing controlled drug-release properties. These properties indicated that SD HASCA was a promising and robust excipient for oral, sustained drug-release, which may possibly minimize the likelihood of dose dumping and consequent adverse effects, even in the case of coadministration with alcohol.

Investigation of preparation conditions and photocatalytic efficiency of nano ZnO using different polysaccharides

The development of a complete set of extensive studies combining both the preparation factors of catalysts and photocatalytic experimental factors for the photodegradation of methylene blue, crystal violet, and Congo red using effective nano zinc oxide (ZnO) obtained from polysaccharides (chitosans, corn starch, and sodium alginate) as chelating agents was the main objective of this study. The influence of nature of polysaccharides, ratio of reactants, calcination temperatures during preparation process, and effects of photocatalytic experimental conditions on photodegradation was investigated. Corn starch and sodium alginate were found to be effective chelating agents and optimum preparation parameters were set as 3:3 % ratio of reactants and 450 °C calcination temperature to prepare nano ZnO with good photocatalytic activity. The order of organic dyes based on their photodegradation rates was arranged as crystal violet > methylene blue > Congo red. Our findings shed light on the optimization of both preparation conditions of photocatalysts and photocatalytic experimental conditions.

Effect of drying technique on some physical properties of cross-linked high amylose/pectin mixtures

Polymers mixtures as well as cross-linking reactions are approaches that have been used successfully to modulate the polymers characteristics in order to improve the control over drug release rate. High amylose and pectin are polysaccharides frequently used to prepare drug delivery systems. Since the drying technique can strongly influence the properties of such systems, the aim of this work was to characterize high amylose/pectin mixtures cross-linked with sodium trimetaphosphate and dried by different techniques - oven and lyophilization. The results showed that samples dried by lyophilization presented reduced particle size, higher porosity and higher swelling ability than the samples dried in oven. Besides, lower thermal stability and different diffraction patterns showed by the former particles should reflect the structural changes as a function of drying technique.

Enzyme replacement therapy for pancreatic insufficiency: present and future

Pancreatic enzyme replacement therapy is currently the mainstay of treatment for nutrient malabsorption secondary to pancreatic insufficiency. This treatment is safe and has few side effects. Data demonstrate efficacy in reducing steatorrhea and fat malabsorption. Effective therapy has been limited by the ability to replicate the physiologic process of enzyme delivery to the appropriate site, in general the duodenum, at the appropriate time. The challenges include enzyme destruction in the stomach, lack of adequate mixing with the chyme in the duodenum, and failing to deliver and activate at the appropriate time. Treatment is begun when clinically significant malabsorption occurs resulting in steatorrhea and weight loss. Treatment failure is addressed in a sequential fashion. Current research is aimed at studying new enzymes and delivery systems to improve the efficiency of action in the duodenum along with developing better means to monitor therapy.