An easy 3D printing approach to manufacture vertical diffusion cells for in vitro release and permeation studies

Vertical diffusion cells are commonly used in the pharmaceutical and cosmetic fields to study the release and permeation of active ingredients through synthetic or biological membranes. Nevertheless, the commercially available glass-based systems are expensive and need to be carefully handled due to their fragility. Fused deposition modeling 3D printing is an additive manufacturing technique that allows producing objects layer by layer using different thermoplastic materials. Among them, polypropylene is a robust, flexible, and chemically inert polymer that can resist to many organic solvents. In this work, we designed and printed a vertical diffusion cell following pharmacopeia requirements by using polypropylene in a fused deposition modeling 3D printer. To keep the system thermostated, the developed model fits in a heating block to avoid the use of water recirculating system. The vertical diffusion cells were leak-free and presented chemical resistance and no interaction with model molecules (i.e., caffeine, diclofenac sodium, and glycyrrhetinic acid). The 3D printed cells were compared to commercially available glass cells and then two different types of synthetic membranes (i.e., PDMS and Strat-M®) were used to evaluate the permeation of a caffeine hydrogel. The developed 3D printed testing system could represent an efficient alternative to the glass-based equipment

3D printed clotrimazole intravaginal ring for the treatment of recurrent vaginal candidiasis

Vulvovaginal candidiasis is a vaginal infection caused by the fungal pathogen Candida albicans that, most commonly, affects women of reproductive age. Its first-line treatment consists in topical applications of conventional drug formulations (e.g., creams, gels, tablets) containing imidazole drugs. The treatment involves single or multiple daily applications and, in the case of recurrences, daily administration of oral antifungal drugs for up to one month. Intravaginal rings are flexible, biocompatible medical devices that, compared to conventional drug formulations, offer the possibility of a controlled vaginal drug delivery over a determined period with a single application, thus increasing patient compliance. Among innovative manufacturing techniques, in recent years, fused deposition modeling 3D printing has emerged in the pharmaceutical field to produce different therapeutics combining drugs and polymers. This technique allows to print objects layer by layer with many different thermoplastic materials after a computer-assisted design. Thermoplastic polyurethanes are flexible and biocompatible materials that can be efficiently employed for the manufacturing of drug release systems, already utilized to prepare vaginal devices. In this work, we produced a clotrimazole-loaded intravaginal ring by fused deposition modeling 3D printing combining the drug with thermoplastic polyurethane using hot melt extrusion. The rings were computer-designed and then printed with two different drug concentrations (i.e., 2% and 10% w/w). The intravaginal rings were first tested in an agar-diffusion test to evaluate their effectiveness against C. albicans; and the 10% loaded ring was selected for further studies. Drug release was evaluated in two different media (i.e., 50% ethanol and vaginal fluid simulant) showing a sustained release over a period of seven days. Next, in vitro time-kill analysis against C. albicans in simulated vaginal fluid was performed and displayed a complete growth inhibition after 5 days, compared to the control. These results suggest a potential application of these 3D printed intravaginal rings for the treatment of vulvovaginal candidiasis and for the long-time treatment of recurrences

Poly(3-hydroxybutyrate): A potential biodegradable excipient for direct 3D printing of pharmaceuticals

During the past decades, 3D printing has revolutionised different areas of research. Despite the considerable progress achieved in 3D printing of pharmaceuticals, the limited choice of suitable materials remains a challenge to overcome. The growing search for sustainable excipients has led to an increasing interest in biopolymers. Poly(3-hydroxybutyrate) (PHB) is a biocompatible and biodegradable biopolymer obtained from bacteria that could be efficiently employed in the pharmaceutical field. Here we aimed to demonstrate its potential application as a thermoplastic material for personalised medicine through 3D printing. More specifically, we processed PHB by using direct powder extrusion, a one-step additive manufacturing technique. To assess and denote the feasibility and versatility of the process, a 3D square model was manufactured in different dimensions (sidexheight: 12x2 mm; 18x2 mm; 24x2 mm) and loaded with increasing percentages of a model drug (up to 30% w/w). The manufacturing process was influenced by the drug content, and indeed, an increase in the amount of the drug determined a reduction in the printing temperature, without affecting the other parameters (such as the layer height). The composition of the model squares was investigated using Fourier-transform infrared spectroscopy, the resulting spectra confirmed that the starting materials were successfully incorporated into the final formulations. The thermal behaviour of the printed systems was characterized by differential scanning calorimetry, and thermal gravimetric analysis. Moreover, the sustained drug release profile of the formulations was performed over 21 days and showed to be dependent on the dimensions of the printed object and on the amount of loaded drug. Indeed, the formulation with 30% w/w in the dimension 24x2 mm released the highest amount of drug. Hence, the results suggested that PHB and direct powder extrusion technique could be promising tools for the manufacturing of prolonged release and personalised drug delivery forms

Development and evaluation of a 3D printing protocol to produce zolpidem-containing printlets, as compounding preparation, by the pressurized-assisted microsyringes technique

Insomnia is a chronic disorder with a mean prevalence ranged from 6% to 15% worldwide. The usual pharmacologic treatment for insomnia has been benzodiazepines and barbiturates. More recently, z-drugs were introduced in the therapeutic arsenal to maximize benefits and minimize treatment damage. Zolpidem tartrate, whose primary indication is for sleep initiation problems, is conventionally used at a recommended dose of 5 mg for women as well as elderly patients (< 65 years-old) and 10 mg for non-elderly men. However, it was demonstrated that the dose of zolpidem should be adjusted according to the gender, age, condition of the patient and the presence of polypharmacy to decrease the occurrence of adverse events. Faced with the therapeutic limitations inherent to marketed products, magistral preparations offer medical and legal alternatives to mass treatment. The use of a semi-automatic technique, with standardized protocol, such as 3D printing should be advantageously implemented as an alternative to standard compounding procedures. In this work, the pressure-assisted microsyringes method was selected as it allows the tridimensional printing, and so the customization of the dose, by easily extruding a viscous semi-liquid material, called "slurry", through a syringe at room temperature. It has been demonstrated that this methodology allows obtaining printlets that responded to the zolpidem-containing tablets monograph of the US pharmacopoeia Edition 42. The compounding preparations proposed in this work therefore have the same criteria of requirements as a commercial form

Effect of temperature increase during the tableting of pharmaceutical materials

Scale-up of tableting process is particularly difficult due to specific concerns related exclusively to the process itself and that cannot be determined on a smaller scale, which are the effect of compression speed and the build-up of heat due to the length of the compaction operations. In this work, it has been simulated the rise of temperature observed during the tablets manufacturing in a full production scale by means of an appropriate modification of a R&D rotary tablet machine. Four common pharmaceutical excipients, characterized by different chemical nature, consolidation behaviour and temperature sensitiveness have been analysed in terms of compaction mechanism (Heckel and energy analysis) and tabletability, in order to verify any effect of the increase of temperature. The results showed a relevance of the temperature on mechanical tablets properties only on materials characterized by low temperature thermal transitions (melting or glass transition), while, for compounds which do not exhibit thermal events at low temperature, it becomes less important for ductile materials and irrelevant for brittle materials. Heckel analysis highlighted a noticeable increase of ductility only in those materials whose tablets mechanical properties depended on the temperature. On the other hand, energy analysis showed low sensitivity failing to identify any temperature effect on compaction materials properties. This work showed how to simulate the process of temperature rise on a small scale and the influence of temperature on materials compaction properties. The use of a modified tableting machine, able to control the temperature and moisture levels and also capable of monitoring the punch movements, resulted in identifying the effect of temperature both on mechanical and compaction properties on materials. Thus, it represents a valuable tool in order to provide useful information at an early stage during the development of tablets formulations

Dynamic mechanical thermal analysis of hypromellose 2910 free films

It is common practice to coat oral solid dosage forms with polymeric materials for controlled release purposes or for practical and aesthetic reasons. Good knowledge of thermo-mechanical film properties or their variation as a function of polymer grade, type and amount of additives or preparation method is of prime importance in developing solid dosage forms. This work focused on the dynamic mechanical thermal characteristics of free films of hypromellose 2910 (also known as HPMC), prepared using three grades of this polymer from two different manufacturers, in order to assess whether polymer chain length or origin affects the mechanical or thermo-mechanical properties of the final films. Hypromellose free films were obtained by casting their aqueous solutions prepared at a specific concentrations in order to obtain the same viscosity for each. The films were stored at room temperature until dried and then examined using a dynamic mechanical analyser. The results of the frequency scans showed no significant differences in the mechanical moduli E' and E" of the different samples when analysed at room temperature; however, the grade of the polymer affected material transitions during the heating process. Glass transition temperature, apparent activation energy and fragility parameters depended on polymer chain length, while the material brand showed little impact on film performance

Development and In Vivo Evaluation of Multidrug Ultradeformable Vesicles for the Treatment of Skin Inflammation

The aim of this work was to evaluate the effect of two chemically different edge activators, i.e., Tween® 80 and sodium deoxycholate, on (i) the physical, mechanical, and biological properties of ultradeformable vesicles, and (ii) the administration of naproxen sodium-loaded multidrug ultradeformable vesicles for the transdermal route in order to obtain therapeutically meaningful drug concentrations in the target tissues and to potentiate its anti-inflammatory effect by association with the antioxidant drug idebenone. The results obtained in this investigation highlighted a synergistic action between naproxen and idebenone in the treatment of inflammatory disease with a more pronounced anti-inflammatory effect in multidrug ultradeformable vesicles compared to the commercial formulation of Naprosyn® gel. Systems made up of Tween® 80 appeared to be the most suitable in terms of percutaneous permeation and anti-inflammatory activity due to the greater deformability of these vesicles compared to multidrug ultradeformable vesicles with sodium deoxycholate. Our findings are very encouraging and suggest the use of these carriers in the topical treatment of inflammatory diseases

Evaluation of methoxy polyethylene glycol-polylactide diblock copolymers as additive in hypromellose film coating

This paper deals with a new application of diblock methoxy polyethylene glycol-polylactide block copolymers, a class of synthetic biomaterials largely studied in the pharmaceutical and biomedical fields owing to their favorable properties such as biocompatibility, biodegradability, low immunogenicity, and good mechanical properties. In this work, these materials were evaluated as additives for gastro-soluble pharmaceutical coating aimed to reduce film stiffness and water permeability. Two copolymers with different polylactide chain lengths were synthesized and characterized in term of molecular weight and solid-state properties. A series of free films with different hypromellose/copolymers ratio were prepared and characterized in terms of appearance, components miscibility, plasticity, and water vapor permeability. The obtained results demonstrate that copolymers effectively influence hypromellose film properties according to their concentration and molecular weight. Specifically, the addition of the copolymer with a molecular weight of 6.5kDa in a ratio hypromellose:polymer 5:1, allowed to obtain films with good appearance, improved plasticization, and water permeability properties. For higher molecular weight, copolymer or different ratios was not possible to observe the improvement of all the properties at the same time. The results also make possible to define the critical features to improve in order to use block copolymers as additive in hypromellose film coating. The availability of new water-soluble additives able to work as plasticizer and moisture sealer in polymeric films represents an important progress not only in the field of pharmaceutical coating but also in that of food coatings, as for example in the formulation of edible films

Permeability-enhancing effects of three laurate-disaccharide monoesters across isolated rat intestinal mucosae

none8sìLaurate (C12)-sucrose esters are established intestinal epithelial permeation enhancers (PEs) with potential for use in oral delivery. Most studies have examined blends of ester rather than specific monoesters, with little variation on the sugar moiety. To investigate the influence of varying the sugar moiety on monoester performance, we compared three monoesters: C12-sucrose, C12-lactose, and C12-trehalose. The assays were: critical micellar concentration (CMC) in Krebs-Henseleit buffer, MTS and lactate dehydrogenase assays in Caco-2 cells, transepithelial electrical resistance (TEER) and apparent permeability coefficient (Papp) of [14C] mannitol across isolated rat intestinal mucosae, and tissue histology. For CMC, the rank order was C12-trehalose (0.21 mM) < C12-sucrose (0.34 mM) < C12-lactose (0.43 mM). Exposure to Caco-2 cells for 120 min produced TC50 values in the MTS assay from 0.1 to 0.4 mM. Each ester produced a concentration-dependent decrease in TEER across rat mucosae with 80% reduction seen with 8 mM in 5 min, but C12-trehalose was less potent. C12-sucrose and C12-lactose increased the Papp of [14C] mannitol across mucosae with similar potency and efficacy, whereas C12-trehalose was not as potent or efficacious, even though it still increased flux. In the presence of the three esters, gross intestinal histology was unaffected except at 8 mM for C12-sucrose and C12-lactose. In conclusion, the three esters enhanced permeability likely via tight junction modulation in rat intestinal tissue. C12-trehalose was not quite as efficacious, but neither did it damage tissue to the same extent. All three can be considered as potential PEs to be included in oral formulations.openMcCartney, Fiona; Perinelli, Diego R; Tiboni, Mattia; Cavanagh, Robert; Lucarini, Simone; Filippo Palmieri, Giovanni; Casettari, Luca; Brayden, David JMccartney, Fiona; Perinelli, Diego R; Tiboni, Mattia; Cavanagh, Robert; Lucarini, Simone; Filippo Palmieri, Giovanni; Casettari, Luca; Brayden, David

3D Printing of Drug-Loaded Thermoplastic Polyurethane Meshes: A Potential Material for Soft Tissue Reinforcement in Vaginal Surgery

Current strategies to treat pelvic organ prolapse (POP) or stress urinary incontinence (SUI), include the surgical implantation of vaginal meshes. Recently, there have been multiple reports of issues generated by these meshes conventionally made of poly(propylene). This material is not the ideal candidate, due to its mechanical properties leading to complications such as chronic pain and infection. In the present manuscript, we propose the use of an alternative material, thermoplastic polyurethane (TPU), loaded with an antibiotic in combination with fused deposition modelling (FDM) to prepare safer vaginal meshes. For this purpose, TPU filaments containing levofloxacin (LFX) in various concentrations (e.g., 0.25%, 0.5%, and 1%) were produced by extrusion. These filaments were used to 3D print vaginal meshes. The printed meshes were fully characterized through different tests/analyses such as fracture force studies, attenuated total reflection-Fourier transform infrared, thermal analysis, scanning electron microscopy, X-ray microcomputed tomography (μCT), release studies and microbiology testing. The results showed that LFX was uniformly distributed within the TPU matrix, regardless the concentration loaded. The mechanical properties showed that poly(propylene) (PP) is a tougher material with a lower elasticity than TPU, which seemed to be a more suitable material due to its elasticity. In addition, the printed meshes showed a significant bacteriostatic activity on both Staphylococcus aureus and Escherichia coli cultures, minimising the risk of infection after implanting them. Therefore, the incorporation of LFX to the TPU matrix can be used to prepare anti-infective vaginal meshes with enhanced mechanical properties compared with current PP vaginal meshes