Anastasia Foppoli

Oral colon delivery of insulin with the aid of functional adjuvants

Oral colon delivery is currently considered of importance not only for the treatment of local pathologies, such as primarily inflammatory bowel disease (IBD), but also as a means of accomplishing systemic therapeutic goals. Although the large bowel fails to be ideally suited for absorption processes, it may indeed offer a number of advantages over the small intestine, including a long transit time, lower levels of peptidases and higher responsiveness to permeation enhancers. Accordingly, it has been under extensive investigation as a possible strategy to improve the oral bioavailability of peptide and protein drugs. Because of a strong underlying rationale, most of these studies have focused on insulin. In the present review, the impact of key anatomical and physiological characteristics of the colon on its viability as a protein release site is discussed. Moreover, the main formulation approaches to oral colon targeting are outlined along with the design features and performance of insulin-based devices.

Hot-melt extruded filaments based on pharmaceutical grade polymers for 3D printing by fused deposition modeling

Fused deposition modeling (FDM) is a 3D printing technique based on the deposition of successive layers of thermoplastic materials following their softening/melting. Such a technique holds huge potential for the manufacturing of pharmaceutical products and is currently under extensive investigation. Challenges in this field are mainly related to the paucity of adequate filaments composed of pharmaceutical grade materials, which are needed for feeding the FDM equipment. Accordingly, a number of polymers of common use in pharmaceutical formulation were evaluated as starting materials for fabrication via hot melt extrusion of filaments suitable for FDM processes. By using a twin-screw extruder, filaments based on insoluble (ethylcellulose, Eudragit(®) RL), promptly soluble (polyethylene oxide, Kollicoat(®) IR), enteric soluble (Eudragit(®) L, hydroxypropyl methylcellulose acetate succinate) and swellable/erodible (hydrophilic cellulose derivatives, polyvinyl alcohol, Soluplus(®)) polymers were successfully produced, and the possibility of employing them for printing 600μm thick disks was demonstrated. The behavior of disks as barriers when in contact with aqueous fluids was shown consistent with the functional application of the relevant polymeric components. The produced filaments were thus considered potentially suitable for printing capsules and coating layers for immediate or modified release, and, when loaded with active ingredients, any type of dosage forms.

Film coatings for oral colon delivery

Oral colon delivery is pursued through a number of formulation strategies with the aim of enabling effective and well-tolerated treatments for large bowel pathologies or enhancing the intestinal absorption of peptide and protein drugs. According to such strategies, coated dosage forms for colonic release may be provided with microbiota, pH, pressure or time-dependent polymeric films. Microbiota-activated coatings are mostly obtained from polysaccharides of natural origin mixed with insoluble structuring excipients. Alternatively, synthetic azo compounds have been employed, generally requiring organic solvents for use as spray-coating agents. On the other hand, pH-sensitive films show responsiveness to pH changes in the lower gut, such as the rise generally observed in the terminal ileum and distal colon or the slight acidification of caecal contents by bacterial fermentation products. Pressure-sensitive coatings are intended for rupturing because of the relatively elevated pressure that may affect solid dosage forms in the large bowel. Finally, time-dependent films are expected to undergo timed erosion, break-up or permeabilization processes irrespective of the aforementioned physiological variables. In this review, the differing films applied for colon delivery purposes are surveyed, and details on their composition, manufacturing and performance are reported.

Feasibility, stability and release performance of a time-dependent insulin delivery system intended for oral colon release.

The aim of the present work was to evaluate the viability of a time-dependent delivery platform (Chronotopic) in preparing an insulin-based system intended for oral colon delivery. The main objectives were to assess the influence of the manufacturing process and storage conditions on the protein stability. Insulin-loaded cores were manufactured by direct compression and were subsequently coated with hydroxypropyl methylcellulose (HPMC) in a top-spray fluid bed up to increasing weight gains, namely 20%, 60% and 100%. In order to evaluate the impact the operating conditions may have on the protein integrity, insulin and its main degradation products (A21-desamido insulin -A21, Other Insulin-Related Compounds -OIRCs, and High-Molecular Weight Proteins -HMWPs) were assayed on samples collected after each process step by chromatographic methods. Furthermore, long-term (4 degrees C) and accelerated (25 degrees C-60% RH) stability studies were carried out on tablet cores and coated systems by assessing insulin, A21, OIRC and HMWP percentages throughout a one-year storage period. In addition, the in vitro release behaviour was investigated during the same study period. The overall results indicated that the manufacturing process is not detrimental for insulin integrity and that 4 degrees C storage temperature alters neither the protein content nor the release performances of the device. It was therefore concluded that insulin-containing systems intended for oral colon delivery can be obtained by the Chronotopic technology.

Influence of betacyclodextrin on the release of poorly soluble drugs from inert and hydrophilic heterogeneous polymeric matrices

The release behavior of poorly soluble drugs (naproxen and ketoprofen) from inert (acrylic resins) and hydrophilic swellable (high-viscosity hydroxypropylmethylcellulose) tableted matrices containing betacyclodextrin (betaCD) was investigated. The results demonstrated that, in both cases, betaCD can enhance the rate of drug release. Matrices obtained from formulations in which lactose replaced betaCD were also evaluated. BetaCD in inert matrices causes a dramatic increase in the rate of drug release, higher than that promoted by lactose which merely acts as a channelling agent. This result suggests that possible in situ formation of the drug-betaCD complex. which causes an improvement in apparent drug solubility, could have a greater influence on the rate of drug release than the possible increase of water uptake by a soluble filler. Indeed, if the opposite were true, lactose would be more effective in increasing the rate of drug release than betaCD, because of its greater solubility in water. On the contrary, in the case of hydrophilic matrices, lactose proves to be much more effective in promoting drug release than betaCD. It seems that, while the bulky interaction compound can freely diffuse through water-filled pores of inert systems, its diffusion through swollen macromolecular chains of hydrophilic matrices may be hindered. This hypothesis was supported by data obtained from binary (drug/polymer) and ternary (drug/polymer/betaCD) hydrophilic matrices using a betaCD-containing dissolution media.

Preparation and evaluation of an oral delivery system for time-dependent colon release of insulin and selected protease inhibitor and absorption enhancer compounds

The aim of this work was to prepare and evaluate an oral dosage form intended for time-dependent colon delivery of insulin along with a selected protease inhibitor (camostat mesilate) and absorption enhancer (sodium glycocholate). A previously described release platform, which had proven potentially suitable for the protein delivery, was exploited. Insulin compatibility with the above-mentioned adjuvants was preliminarily evaluated. For this purpose, the drug and its main degradation products were assayed by HPLC in insulin powder mixtures with camostat mesilate and/or sodium glycocholate stored 12 months at 4 degrees C. No significant decrease in protein content or increase in degradation product percentages beyond Eur. Ph. 6th Ed. limits was highlighted. Moreover, calorimetric studies performed on physical and compacted binary insulin mixtures with camostat mesilate and sodium glycocholate showed that the thermal behavior of both adjuvants was unchanged. Subsequently, tablet cores with differing compositions were prepared and spray-coated with an aqueous HPMC solution in order to obtain pulsatile delivery systems. The coated units were demonstrated to concurrently release the drug and the adjuvants in a prompt and quantitative mode after consistent lag times. Based on these results, the device was proven a potential candidate for colon delivery of insulin and the selected adjuvants.

Injection-molded capsular device for oral pulsatile release: Development of a novel mold

The development of a purposely devised mold and a newly set up injection molding (IM) manufacturing process was undertaken to prepare swellable/erodible hydroxypropyl cellulose-based capsular containers. When orally administered, such devices would be intended to achieve pulsatile and/or colonic time-dependent delivery of drugs. An in-depth evaluation of thermal, rheological, and mechanical characteristics of melt formulations/molded items made of the selected polymer (Klucel® LF) with increasing amounts of plasticizer (polyethylene glycol 1500, 5%-15% by weight) was preliminarily carried out. On the basis of the results obtained, a new mold was designed that allowed, through an automatic manufacturing cycle of 5 s duration, matching cap and body items to be prepared. These were subsequently filled and coupled to give a closed device of constant 600 μm thickness. As compared with previous IM systems having the same composition, such capsules showed improved closure mechanism, technological properties, especially in terms of reproducibility of the shell thickness, and release performance. Moreover, the ability of the capsular container to impart a constant lag phase before the liberation of the contents was demonstrated irrespective of the conveyed formulation.

Thermal and structural properties of ambroxol polymorphs

The thermal and structural characteristics of two crystal forms of ambroxol, (trans-((amino-2-dibromo-3,5-benzyl)amino)-4-cyclohexanol), a drug with remarkable mucolytic and expectorant properties marketed in several drug products, were investigated. Form II (m.p. 92.4°C) is obtained by spontaneous cooling from a hot water/ethanol solution while Form I (m.p. 99.5°C) slowly separates from the mother liquor. The two forms can be identified by PXRD and DSC analyses. On the basis of both thermal and structural data the thermodynamic relationship of enantiotropy was deduced. No metastable (Form I)?stable (Form II) conversion was observed upon storage at ambient conditions. Form I crystallizes in the space group P21/n (alternative setting of P21/c) with Z=8. Form II crystallizes in the space group P21/c with Z=4 and a significantly different crystal packing arrangement from that in Form I. A third crystalline modification, Form III (space group P21/c with Z=16) was detected on cooling a single crystal of Form I down to -70°C. On warming to ambient temperature Form III was found to revert to Form I. This reversible single crystal to single crystal transition was structurally characterised and found to involve subtle changes in the types and extent of molecular disorder as well as the hydrogen bonding arrangement.

3D printed multi-compartment capsular devices for two-pulse oral drug delivery

&NA; In the drug delivery area, versatile therapeutic systems intended to yield customized combinations of drugs, drug doses and release kinetics have drawn increasing attention, especially because of the advantages that personalized pharmaceutical treatments would offer. In this respect, a previously proposed capsular device able to control the release performance based on its design and composition, which could extemporaneously be filled, was improved to include multiple separate compartments so that differing active ingredients or formulations may be conveyed. The compartments, which may differ in thickness and composition, resulted from assembly of two hollow halves through a joint also acting as a partition. The systems were manufactured by fused deposition modeling (FDM) 3D printing, which holds special potential for product personalization, and injection molding (IM) that would enable production on a larger scale. Through combination of compartments having wall thickness of 600 or 1200 &mgr;m, composed of promptly soluble, swellable/erodible or enteric soluble polymers, devices showing two‐pulse release patterns, consistent with the nature of the starting materials, were obtained. Systems fabricated using the two techniques exhibited comparable performance, thus proving the prototyping ability of FDM versus IM. Graphical abstract Figure. No caption available.

Dry Coating of Soft Gelatin Capsules with HPMCAS

Dry coating is an innovative powder-layering technique that enables the formation of coatings on solid dosage forms with no need for using water or organic solvents. This technique envisages the distribution of polymer powder blends onto substrate cores and the concurrent or alternate nebulization of liquid plasticizers. In this work, a dry coating process based on hydroxypropyl methylcellulose acetate succinate (HPMCAS) was set up in a rotary fluid bed equipment to prepare enteric-coated soft gelatin capsules. Promising results were obtained in terms of process feasibility and product characteristics, thus suggesting the possibility of advantageous applications for the investigated technique when dealing with gelatin capsule substrates.