Maximising success in multidrug formulation development: A review

Formulation of minitablets with personalised dissolution profile by fluid-bed granulation ofdrug nanosuspensions

Transforming poorly soluble active pharmaceutical ingredients (APIs) into a nanoparticulate form is a proven way of improving their dissolution characteristics. The preparation of API nanosuspensions is commonly achieved by wet-stirred media milling. The challenge lies in converting the nanosuspension into a solid dosage form without compromising its re-dispersibility. In the present work, an API nanosuspension was combined with additional excipients and used as abinder in fluid-bed granulation to obtain granules with systematically varying dissolution properties. Specifically, polymeric excipients (hydroxypropyl methylcellulose grade E5 and polyvinylpyrrolidone grade K30) were used in the nanosuspension binder to granulate microcrystalline cellulose or Pearlitol CR-H substrate. The resulting granules were used as feed material to prepare minitablets whose combination enabled the formation of multi-unit dosage form (MUDF) capsules with tuneable drug release profiles, paving the way to rational design and manufacturing of precision medicines.

Errors associated with co-names of medicines: The nomenclature of combination medicinal products

In comparison to the efforts required to bring a new drug or formulation to the clinic, bestowing a name on a medicine is relatively simple. However, if the name we choose causes confusion-by making its contents ambiguous or if it is too alike another drug-it can precipitate clinical errors. This prompted the World Health Organization to set up the International Nonproprietary Naming Committee in the 1970s to select unambiguous names for drugs. Unfortunately, multidrug products-which are becoming increasingly popular-do not fall under the remit of conventional International Non-proprietary Nomenclature. We have identified 26 combination formulations that have been historically named with the co-drug format in the United Kingdom. Most of them have also been prescribed in the United Kingdom in the past year, and although several of them are not prescribed very often, 11 were prescribed more than 2000 times. In this paper, we have explored the literature to identify prescribing errors with co-drug products and found several idiosyncrasies that have caused drug errors in the past. We advocate for a standard nomenclature (state the international nonproprietary name [INN] of each component followed by dose information in the x + y format) for these products on the box and in prescribing resources. We hope that this will enhance clarity and safety during prescribing and administration, particularly for high-volume drugs like paracetamol + codeine (co-codamol), amoxicillin + clavulanic acid (co-amoxiclav) and trimethoprim + sulfamethoxazole (co-trimoxazole).

Apixaban and clopidogrel in a fixed-dose combination: Formulation and in vitro evaluation

Fixed-dose combination (FDC) products represent a novel, safe, and cost-effective formulation. Combined use of anticoagulant and antiplatelet medications is common among comorbid cardiovascular patients. This study aimed to formulate FDC tablets for Apixaban and Clopidogrel, as prophylaxis and treatment of thrombo-embolic events. FDC tablets were developed by combining small tablets of Immediate-Release Clopidogrel 75 mg and Extend-Release Apixaban 5 mg through direct compression and wet granulation. Particularly, Apixaban tablets were developed using design expert software, and various types and concentrations of polymers were entered. For Clopidogrel tablets, various diluents were used to develop the formulation. Then, the dissolution profile for each formula was studied. Finally, the optimized formulations were encapsulated within hard gelatin capsules. Apixaban formulation followed zero-order with super case Ⅱ transport mechanism as the dominant mechanism of drug release. The Apixaban drug release rate was affected by the type and concentration of the polymers in the formulation (P < 0.05). As the HPMC concentration was increased, Apixaban release was retarded. For, Clopidogrel, the formulated tablets with spray-dried lactose filler and sodium stearyl fumarate lubricant were found to be stable with good properties. In conclusion, the optimum formulation yielded Clopidogrel and extended-release Apixaban for 24 h with the desired in vitro drug dissolution.

An analysis of multidrug multicomponent crystals as tools for drug development

In a typical tablet or capsule formulation, the active drug is often present as a crystalline solid. This solid emerges from the relationships between the individual atoms within the crystal, which confer a distinct set of physical properties. Then, it follows that if we modify the packing arrangement of the individual molecules within these crystals, we can modulate their properties. This can be achieved by crystal engineering. Crystal engineering has also seen teams arrange multiple drug molecules within the same crystal, resulting in dramatic improvements to drug properties in the lab. The success of drugs like SEGLENTIS® and Entresto® have revitalised interest in these forms, but controversy surrounding their translation has prompted this reconsideration of their clinical utility. I reflect on the current academic, clinical, and commercial interest in multidrug multicomponent crystals, drawing parallels with developments pre-Bragg, contributing to a nuanced understanding of the potential and limitations of crystal engineering in pharmaceutical applications.

3D printing processes in precise drug delivery for personalized medicine

With the advent of personalized medicine, the drug delivery system will be changed significantly. The development of personalized medicine needs the support of many technologies, among which three-dimensional printing (3DP) technology is a novel formulation-preparing process that creates 3D objects by depositing printing materials layer-by-layer based on the computer-aided design method. Compared with traditional pharmaceutical processes, 3DP produces complex drug combinations, personalized dosage, and flexible shape and structure of dosage forms (DFs) on demand. In the future, personalized 3DP drugs may supplement and even replace their traditional counterpart. We systematically introduce the applications of 3DP technologies in the pharmaceutical industry and summarize the virtues and shortcomings of each technique. The release behaviors and control mechanisms of the pharmaceutical DFs with desired structures are also analyzed. Finally, the benefits, challenges, and prospects of 3DP technology to the pharmaceutical industry are discussed.

Complexation: An Interesting Pathway for Combining Two APIs at the Solid State

Combining different drugs into a single crystal form is one of the current challenges in crystal engineering, with the number of reported multi-drug solid forms remaining limited. This paper builds upon an efficient approach to combining Active Pharmaceutical Ingredients (APIs) containing carboxylic groups in their structure with APIs containing pyridine moieties. By transforming the former into their zinc salts, they can be successfully combined with the pyridine-containing APIs. This work highlights the successfulness of this approach, as well as the improvement in the physical properties of the obtained solid forms.

Model-Based Evaluation of Drying Kinetics and Solvent Diffusion in Pharmaceutical Thin Film Coatings

PURPOSE

Fluid-bed coating processes make it possible to manufacture pharmaceutical products with tuneable properties. The choice of polymer type and coating thickness provides control over the drug release characteristics, and multi-layer pellet coatings can combine several active ingredients or achieve tailored drug release profiles. However, the fluid-bed coating is a parametrically sensitive process due to the simultaneous occurrence of polymer solution spraying and solvent evaporation. Designing a robust fluid-bed coating process requires the knowledge of thin film drying kinetics, which in turn critically depends on an accurate description of concentration-dependent solvent diffusion in the polymer.

METHODS

This work presents a mathematical model of thin film drying as an enabling tool for fluid-bed process design. A custom-built benchtop drying cell able to record and evaluate the drying kinetics of a chosen polymeric excipient has been constructed, validated, and used for data collection.

RESULTS

A semi-empirical mathematical model combining heat transfer, mass transfer, and film thickness evolution was formulated and used for estimating the solvent diffusion coefficient and solvent distribution in the polymer layer. The combined experimental and computational methodology was then used for analysing the drying kinetics of common polymeric excipients: poly(vinylpyrrolidone) and two grades of hydroxypropyl methylcellulose.

CONCLUSIONS

The experimental setup together with the mathematical model represents a valuable tool for predictive modeling of pharmaceutical coating processes.

Investigating Structural Property Relationships to Enable Repurposing of Pharmaceuticals as Zinc Ionophores

The importance of zinc in biology has gained greater recognition in recent years due to its essential contributions to the function of many endogenous enzymes. Disruption of zinc homeostasis may be useful in treating pathological conditions, such as Alzheimer's, and for antiviral purposes. Despite the growth of knowledge and increased interest in zinc, little is known about the structure and function of zinc ionophores. In this study we analyse the Cambridge Structural Database and solution complexation studies found in the literature to identify key functional groups which may confer zinc ionophorism. Pharmaceuticals, nutraceuticals and amino acids with these functionalities were selected to enable us to explore the translatability of ionophoric activity from in vitro assays to cellular systems. We find that although certain species may complex to zinc in the solid and solution states, and may carry ions across simple membrane systems, this does not necessarily translate into ionophoric activity. We propose that the CSD can help refine key functionalities but that ionophoric activity must be confirmed in cellular systems.

Impact of Simulated Intestinal Fluids on Dissolution, Solution Chemistry, and Membrane Transport of Amorphous Multidrug Formulations

The solution behavior and membrane transport of multidrug formulations were herein investigated in a biorelevant medium simulating fasted conditions. Amorphous multidrug formulations were prepared by the solvent evaporation method. Combinations of atazanavir (ATV) and ritonavir (RTV) and felodipine (FDN) and indapamide (IPM) were prepared and stabilized by a polymer for studying their dissolution (under non-sink conditions) and membrane transport in fasted state simulated intestinal fluid (FaSSIF). The micellar solubilization by FaSSIF enhanced the amorphous solubility of the drugs to different extents. Similar to buffer, the maximum achievable concentration of drugs in combination was reduced in FaSSIF, but the extent of reduction was affected by the degree of FaSSIF solubilization. Dissolution studies of ATV and IPM revealed that the amorphous solubility of these two drugs was not affected by FaSSIF solubilization. In contrast, RTV was significantly affected by FaSSIF solubilization with a 30% reduction in the maximum achievable concentration upon combination to ATV, compared to 50% reduction in buffer. This positive deviation by FaSSIF solubilization was not reflected in the mass transport–time profiles. Interestingly, FDN concentrations remain constant until the amount of IPM added was over 1000 μg/mL. No decrease in the membrane transport of FDN was observed for a 1:1 M ratio of FDN-IPM combination. This study demonstrates the importance of studying amorphous multidrug formulations under physiologically relevant conditions to obtain insights into the performance of these formulations after oral administration.

Modular design principle based on compartmental drug delivery systems

The current manufacturing solutions for oral solid dosage forms are fundamentally based on technologies from the 19th century. This approach is well suited for mass production of one-size-fits-all products; however, it does not allow for a straight-forward personalization and mass customization of the pharmaceutical end-product. In order to provide better therapies to the patients, a need for innovative manufacturing concepts and product design principles has been rising. Additive manufacturing opens up a possibility for compartmentalization of drug products, including design of spatially separated multidrug and functional excipient compartments. This compartmentalized solution can be further expanded to modular design thinking. Modular design is referring to combination of building blocks containing a given amount of drug compound(s) and related functional excipients into a larger final product. Implementation of modular design principles is paving the way for implementing the emerging personalization potential within health sciences by designing compartmental and reactive product structures that can be manufactured based on the individual needs of each patient. This review will introduce the existing compartmentalized product design principles and discuss the integration of these into edible electronics allowing for innovative control of drug release.

Hyaluronan-based Multifunctional Nano-carriers for Combination Cancer Therapy

Hyaluronan (HA) is a natural linear polysaccharide that has excellent hydrophilicity, biocompatibility, biodegradability, and low immunogenicity, making it one of the most attractive biopolymers used for biomedical researches and applications. Due to the multiple functional sites on HA and its intrinsic affinity for CD44, a receptor highly expressed on various cancer cells, HA has been widely engineered to construct different drug-loading nanoparticles (NPs) for CD44-targeted anti-tumor therapy. When a cocktail of drugs is co-loaded in HA NP, a multifunctional nano-carriers could be obtained, which features as a highly effective and self-targeting strategy to combat cancers with CD44 overexpression. The HA-based multidrug nano-carriers can be a combination of different drugs, various therapeutic modalities, or the integration of therapy and diagnostics (theranostics). Up to now, there are many types of HA-based multidrug nano-carriers constructed by different formulation strategies, including drug co-conjugates, micelles, nano-gels and hybrid NP of HA and so on. This multidrug nano-carrier takes the full advantages of HA as an NP matrix, drug carriers and targeting ligand, representing a simplified and biocompatible platform to realize the targeted and synergistic combination therapy against the cancers. In this review, recent progress of HA-based multidrug nano-carriers for combination cancer therapy is summarized and the potential challenges for translational applications have been discussed.

Improved in vitro and in vivo properties of telmisartan in the co-amorphous system with hydrochlorothiazide: A potential drug-drug interaction mechanism prediction

The aim of this study is to improve in vitro and in vivo properties of an antihypertensive poorly soluble drug Telmisartan (TEL) by co-amorphization with a pharmacologically relevant drug Hydrochlorothiazide (HCT), and to improve the stability of single amorphous drugs. Herein, TEL-HCT co-amorphous systems (CAMs) (1:1, 2:3, 1:2, 1:3) were prepared by solvent evaporation. The apparent solubility and the dissolution of TEL in the TEL-HCT CAM (1:3) were increased by 79 times and 10 times compared to crystalline TEL, which showed the optimal properties. C_max and AUC_0-48h value of TEL-HCT CAM (1:3) were 10-fold and 3-fold as the crystalline state. Moreover, TEL-HCT CAM (1:3) remained stable in 60 °C, 0 % RH (30 days), 40 °C, 75 % RH (90 days) and 25 °C, 0 % RH (180 days). Positive ΔT_gs were observed in all CAMs, suggesting the existence of potential intermolecular force. Fourier Transform-Infrared and Raman spectra were used to further prove the drug-drug interaction and predict potential mechanisms. Therefore, in the strategy of combined medication, CAM provides a promising way to transfer drugs with poor properties into systems with enhanced dissolution, greater bioavailability, and stabilized amorphous state, which has been proven in this study.

Prediction of Synergistic Drug Combinations for Prostate Cancer by Transcriptomic and Network Characteristics

Prostate cancer (PRAD) is a major cause of cancer-related deaths. Current monotherapies show limited efficacy due to often rapidly emerging resistance. Combination therapies could provide an alternative solution to address this problem with enhanced therapeutic effect, reduced cytotoxicity, and delayed the appearance of drug resistance. However, it is prohibitively cost and labor-intensive for the experimental approaches to pick out synergistic combinations from the millions of possibilities. Thus, it is highly desired to explore other efficient strategies to assist experimental researches. Inspired by the challenge, we construct the transcriptomics-based and network-based prediction models to quickly screen the potential drug combination for Prostate cancer, and further assess their performance by in vitro assays. The transcriptomics-based method screens nine possible combinations. However, the network-based method gives discrepancies for at least three drug pairs. Further experimental results indicate the dose-dependent effects of the three docetaxel-containing combinations, and confirm the synergistic effects of the other six combinations predicted by the transcriptomics-based model. For the network-based predictions, in vitro tests give opposite results to the two combinations (i.e. mitoxantrone-cyproheptadine and cabazitaxel-cyproheptadine). Namely, the transcriptomics-based method outperforms the network-based one for the specific disease like Prostate cancer, which provide guideline for selection of the computational methods in the drug combination screening. More importantly, six combinations (the three mitoxantrone-containing and the three cabazitaxel-containing combinations) are found to be promising candidates to synergistically conquer Prostate cancer.

Modulation of the powder properties of lamotrigine by crystal forms

The mechanical properties of powders determine the ease of manufacture and ultimately the quality of the oral solid dosage forms. Although poor mechanical properties of an active pharmaceutical ingredient (API) can be mitigated by using suitable excipients in a formulation, the effectiveness of that approach is limited for high dose drugs or multidrug tablets. In this context, improving the mechanical properties of the APIs through solid form optimisation is a good strategy to address such a challenge. This work explores the powder and tableting properties of various lamotrigine (LAM) solid forms with the aim to facilitate direct compression by overcoming the poor tabletability of LAM. The two drug-drug crystals of LAM with nicotinamide and valproic acid demonstrate superior flowability and tabletability over LAM. The improved powder properties are rationalised by structure analysis using energy framework, scanning electron microscopy, and Heckel analysis.

Drug-Drug Binary Solids of Nitrofurantoin and Trimethoprim: Crystal Engineering and Pharmaceutical Properties

With the aim of developing multidrug solids through a tuned crystal engineering approach, we have selected two antiurinary infective drugs, namely, nitrofurantoin (NF) and trimethoprim (TMP) and isolated eight binary drug-drug solid solvates along with a nonsolvated cocrystal. Crystal structure analyses were performed for eight of these solids and rationalized in terms of known supramolecular synthons formed by pyrimidine, imide, and amine functionalities. Notably, the TMP-NF anhydrous cocrystal and its ionic cocrystal hydrate exhibit enhanced equilibrium solubilities compared to pure NF or the simple NF hydrate. Furthermore, the ionic cocrystal hydrate exhibits greater antibacterial activity against the Gram-negative bacteria, E. coli, compared to the parent TMP and NF at the lowest concentration of 3.9 μg/mL. This study indicates initial pathways using the cocrystal methodology that would help to eventually arrive at an antiurinary cocrystal with optimal properties.

Insights into Dissolution and Solution Chemistry of Multidrug Formulations of Antihypertensive Drugs

Using fixed dose combinations of drugs instead of administering drugs separately can be beneficial for both patients and the health care system, but the current understanding of how multidrug formulations work at the molecular level is still in its infancy. Here, we explore dissolution, solubility, and supersaturation of various drug combinations in amorphous formulations. The effect of chemical structural similarity on combination behavior was investigated by using structurally related compounds of both drugs. The effect of polymer type on solution behavior was also evaluated using chemically diverse polymers. Indapamide (IPM) concentration decreased when combined with felodipine (FDN) or its analogues, which occurred even when the IPM solution was undersaturated. The extent of solubility decrease of FDN was less than that of IPM from the dissolution of an equimolar formulation of the drugs. No significant solubility decrease was observed for FDN at low contents of IPM which was also observed for other dihydropyridines, whereas FDN decreases at high contents of IPM. This was explained by the complex nature of the colloidal precipitates of the combinations which impacts the chemical potential of the drugs in solution at different levels. The maximum achievable concentration of FDN and IPM during dissolution of the polyvinylpyrrolidone-based amorphous solid dispersion was higher than the value measured with the hydroxypropyl methylcellulose acetate succinate-based formulation. This emphasizes the significance of molecular properties and chemical diversity of drugs and polymers on solution chemistry and solubility profiles. These findings may apply to drugs administered as a single dosage form or in separate dosage forms and hence need to be well controlled to assure effective treatments and patient safety.

Development of 3D-Printed Layered PLGA Films for Drug Delivery and Evaluation of Drug Release Behaviors

3D printing has been widely used to rapidly manufacture a variety of solid dosage forms on-demand, without sacrificing precision. This study used extrusion-based 3D printing to prepare single-layered, tri-layered, and core-in-shell poly(lactic-co-glycolic acid) (PLGA) films carrying paclitaxel and rapamycin in combination or lidocaine alone. Each layer was composed of either low molecular weight (MW) PLGA or high MW PLGA. In vitro drug release kinetics of paclitaxel, rapamycin, and lidocaine for PLGA films were assessed and compared with PLGA-polyethylene glycol (PEG)-PLGA hydrogel discs. Regardless of the structure of PLGA film, paclitaxel (half-time: 54-63 days) was released faster than when compared with rapamycin (half-time: 74-80 days). In contrast, single-layered PLGA-PEG-PLGA discs released rapamycin (half-time 5.7 h) at a more rapid rate than paclitaxel (half-time: 7.3 h). Single-layered PLGA-PEG-PLGA discs enabled a faster drug release than PLGA films, noting that the disc matrices dissolve in water in 24 h. Similarly, lidocaine incorporated in PLGA films (half-time: 13-36 days) exhibited slower release patterns than that in PLGA-PEG-PLGA discs (half-time: 2.6 h). In vitro drug release patterns were explained using molecular models that simulate drug-polymer interactions. Analysis of models suggested that drug-polymer interactions, location of each drug in the polymeric matrix, and solubility of drugs in water were major factors that determine drug release behaviors from the polymeric films and discs.

Patient Centric Pharmaceutical Drug Product Design-The Impact on Medication Adherence

Medication adherence is a growing concern for public health and poor adherence to therapy has been associated with poor health outcomes and higher costs for patients. Interventions for improving adherence need to consider the characteristics of the individual therapeutic regimens according to the needs of the patients. In particular, geriatric and paediatric populations as well as dermatological patients have special needs/preferences that should be considered when designing drug products. Patient Centric Drug Product Pharmaceutical Design (PCDPD) offers the opportunity to meet the needs and preferences of patients. Packaging, orodispersible formulations, fixed dose combinations products, multiparticulate formulations, topical formulations and 3D printing are of particular relevance in a PCDPD process. These will be addressed in this review as well as their impact on medication adherence.

3D-Printed Solid Dispersion Drug Products

With the well-known advantages of additive manufacturing methods such as three-dimensional (3D) printing in drug delivery, it is disappointing that only one product has been successful in achieving regulatory approval in the past few years. Further research and development is required in this area to introduce more 3D printed products into the market. Our study investigates the potential of fixed dose combination solid dispersion drug products generated via 3D printing. Two model drugs-fluorescein sodium (FS) and 5-aminosalicyclic acid (5-ASA)-were impregnated onto a polyvinyl alcohol (PVA) filament, and the influence of solvent choice in optimal drug loading as well as other influences such as the physicochemical and mechanical properties of the resultant filaments were investigated prior to development of the resultant drug products. Key outcomes of this work included the improvement of filament drug loading by one- to threefold due to solvent choice on the basis of its polarity and the generation of a 3D-printed product confirmed to be a solid dispersion fixed dose combination with the two model drugs exhibiting favourable in vitro dissolution characteristics.

3D Printing of a Multi-Layered Polypill Containing Six Drugs Using a Novel Stereolithographic Method

Three-dimensional printing (3DP) has demonstrated great potential for multi-material fabrication because of its capability for printing bespoke and spatially separated material conformations. Such a concept could revolutionise the pharmaceutical industry, enabling the production of personalised, multi-layered drug products on demand. Here, we developed a novel stereolithographic (SLA) 3D printing method that, for the first time, can be used to fabricate multi-layer constructs (polypills) with variable drug content and/or shape. Using this technique, six drugs, including paracetamol, caffeine, naproxen, chloramphenicol, prednisolone and aspirin, were printed with different geometries and material compositions. Drug distribution was visualised using Raman microscopy, which showed that whilst separate layers were successfully printed, several of the drugs diffused across the layers depending on their amorphous or crystalline phase. The printed constructs demonstrated excellent physical properties and the different material inclusions enabled distinct drug release profiles of the six actives within dissolution tests. For the first time, this paper demonstrates the feasibility of SLA printing as an innovative platform for multi-drug therapy production, facilitating a new era of personalised polypills.

Inhibition of Co-Crystallization of Olmesartan Medoxomil and Hydrochlorothiazide for Enhanced Dissolution Rate in Their Fixed Dose Combination

Olmesartan medoxomil (Olm) and hydrochlorothiazide (HCTZ) are fixed dose combination (FDC) for treatment of hypertension. They have hydrogen bonding sites and may interact during co-processing. The consequences of such interaction are not clear. This study investigated the possibility of this interaction during co-processing. The research was extended to inhibit deleterious interactions. The drugs were co-evaporated from ethanolic solution to maximize the chance of interaction. This was performed in the absence and presence of hydroxypropyl methylcellulose (HPMC) and/or aerosil. The products were characterized using Fourier transform infrared spectroscopy (FTIR), differential thermal analysis, and powder X-ray diffraction (PXRD) in addition to dissolution studies. Co-evaporation of Olm with HCTZ in the absence of excipients produced crystalline material with FTIR spectrum showing intermolecular hydrogen bonding. This material showed thermal pattern of new crystalline species. This was identified as Olm/HCTZ co-crystal by PXRD. This co-crystallization reduced the dissolution rate of both drugs. This co-crystallization was inhibited in the presence of HPMC, but the dissolution rate was not significantly enhanced accordingly. Co-processing in the presence of both HPMC and aerosil eliminated the co-crystallization and minimized the intermolecular drug-drug interaction with subsequent dissolution enhancement. The study introduced a composition for fixed dose combination of Olm and HCTZ with enhanced dissolution.