Evaluating Suspension Formulations of Theophylline Cocrystals With Artificial Sweeteners

Sweetening the Deal: Sweetener-Based Ionic Liquid of Albendazole Significantly Enhances Its Solubility and Oral Bioavailability

Albendazole (ABZ) is a hydrophobic and weakly basic anthelmintic benzimidazole with a very low (5%) oral bioavailability. Conversion of hydrophobic ionizable drugs such as ABZ into ionic liquids (ILs) or liquid salts is an emerging strategy for improving their solubility and oral bioavailability. To date, FDA-approved non-nutritive anionic sweeteners have not been evaluated for the development of ILs of weakly basic and hydrophobic drugs. Hence, we evaluated the ability of various anionic non-nutritive sweeteners, acesulfame potassium (ACE-K), saccharin sodium (SAC-Na), and cyclamate sodium (CYM-Na), to transform ABZ into an IL. Interestingly, only ACE-K, upon interaction with ABZ at the ABZ to ACE molar ratio of 1:2, converted ABZ into a room-temperature IL [ABZ-ACE (1:2) IL], whereas SAC-Na and CYM-Na yielded salts or coamorphous systems. The interaction of ABZ with anionic sweeteners was confirmed using FT-IR and NMR. Compared to pure ABZ, all ABZ-sweetener ILs/salts/coamorphous systems displayed a 1.2- to 2-fold decrease in Log P value and a significant increase in the equilibrium solubility of ABZ in water, pH 1.2 buffer, and pH 6.8 buffer. ABZ-ACE (1:2) IL exhibited remarkably higher (∼92-fold) solubility in water and ∼5-fold improvement in pH 6.8 buffer solubility, with a complete lack of crystallinity at room temperature, even after 1 month of storage at room temperature. Finally, compared to ABZ oral suspension, orally delivered ABZ-ACE (1:2) IL showed an 11-fold increment in Cmax and a 7.6-fold increase in the oral bioavailability of ABZ in mice. Hence, the development of a sweetener-based IL could be an effective approach to improving the solubility and oral bioavailability of hydrophobic weakly basic drugs, including ABZ.

Kollicoat® Smartseal 100P for Developing Theophylline Pellets: Exploring Taste-Masking Potential for Pediatric Applications

Background/Objectives: This study aimed to develop and evaluate taste-masked theophylline pellets using hot-melt extrusion (HME) technology. Additionally, the study evaluates the efficacy of various taste-masking polymers by comparing three pH-dependent polymers, Kollicoat® Smartseal 100P, Eudragit® EPO, and Kollicoat® MAE 100-55, in masking taste and optimizing drug release. Methods: Formulations were designed with varying drug loads (10%, 20%, and 30%) and plasticizer concentrations (20% and 30% PEG 1500). Lead formulations were characterized using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), bitter threshold level, and in vitro release testing. Stability was assessed under accelerated conditions (40 °C ± 2 °C and 75% ± 5% RH) for three months. Results: DSC confirmed homogenous dispersion of the drug within the polymer matrix. The optimized formulation comprising 20% theophylline, 20% PEG 1500, and 60% Kollicoat® Smartseal 100P demonstrated effective taste masking, releasing only 1.1% of the drug in simulated salivary fluid (SSF) within two minutes, significantly lower than the pure drug (29.5%, p < 0.05), Kollicoat® MAE 100-55 (2.8%, p < 0.05), and comparable to Eudragit® EPO (2.1%, p > 0.05). Solubility studies further confirmed that theophylline release from the lead formulations remained well below its reported bitter threshold, which could prevent taste perception and mitigate bitterness. In gastric fluid, complete drug release was achieved from Kollicoat® Smartseal 100P and Eudragit® EPO, while Kollicoat® MAE 100-55 exhibited limited release. Stability studies showed that the Kollicoat® Smartseal 100P formulation maintained its texture, taste-masking efficacy, and dissolution profile under accelerated conditions. Conclusions: The study demonstrates the novel exploration of Kollicoat® Smartseal 100P for HME application, and its effectiveness in achieving robust taste masking for theophylline, improving patient compliance, particularly in pediatric and geriatric populations.

An industrial perspective on co-crystals: Screening, identification and development of the less utilised solid form in drug discovery and development

Active pharmaceutical ingredients are commonly marketed as a solid form due to ease of transport, storage and administration. In the design of a drug formulation, the selection of the solid form is incredibly important and is traditionally based on what polymorphs, hydrates or salts are available for that compound. Co-crystals, another potential solid form available, are currently not as readily considered as a viable solid form for the development process. Even though co-crystals are gaining an ever-increasing level of interest within the pharmaceutical community, their acceptance and application is still not as standard as other solid forms such as the ubiquitous pharmaceutical salt and stabilised amorphous formulations. Presented in this chapter is information that would allow for a co-crystal screen to be planned and conducted as well as scaled up using solution and mechanochemistry based methods commonly employed in both the literature and industry. Also presented are methods for identifying the formation of a co-crystal using a variety of analytical techniques as well as the importance of confirming the formation of co-crystals from a legal perspective and demonstrating the legal precedent by looking at co-crystalline products already on the market. The benefits of co-crystals have been well established, and presented in this chapter are a selection of examples which best exemplify their potential. The goal of this chapter is to increase the understanding of co-crystals and how they may be successfully exploited in early stage development.

Unexpected Salt/Cocrystal Polymorphism of the Ketoprofen-Lysine System: Discovery of a New Ketoprofen-l-Lysine Salt Polymorph with Different Physicochemical and Pharmacokinetic Properties

Ketoprofen–l-lysine salt (KLS) is a widely used nonsteroidal anti-inflammatory drug. Here, we studied deeply the solid-state characteristics of KLS to possibly identify new polymorphic drugs. Conducting a polymorph screening study and combining conventional techniques with solid-state nuclear magnetic resonance, we identified, for the first time, a salt/cocrystal polymorphism of the ketoprofen (KET)–lysine (LYS) system, with the cocrystal, KET–LYS polymorph 1 (P1), being representative of commercial KLS, and the salt, KET–LYS polymorph 2 (P2), being a new polymorphic form of KLS. Interestingly, in vivo pharmacokinetics showed that the salt polymorph has significantly higher absorption and, thus, different pharmacokinetics compared to commercial KLS (cocrystal), laying the basis for the development of faster-release/acting KLS formulations. Moreover, intrinsic dissolution rate (IDR) and electronic tongue analyses showed that the salt has a higher IDR, a more bitter taste, and a different sensorial kinetics compared to the cocrystal, suggesting that different coating/flavoring processes should be envisioned for the new compound. Thus, the new KLS polymorphic form with its different physicochemical and pharmacokinetic characteristics can open the way to the development of a new KET–LYS polymorph drug that can emphasize the properties of commercial KLS for the treatment of acute inflammatory and painful conditions.

Cocrystal engineering of pharmaceutical solids: therapeutic potential and challenges

This highlight presents an overview of pharmaceutical cocrystal production and its potential in reviving problematic properties of drugs in different dosage forms. The challenges and future outlook of its translational development are discussed.

Cocrystal Solubility Advantage and Dose/Solubility Ratio Diagrams: A Mechanistic Approach To Selecting Additives and Controlling Dissolution-Supersaturation-Precipitation Behavior

Two of the main questions regarding cocrystal selection and formulation development are whether the will be stable and how fast can it dissolve the drug dose. Dissolving the drug dose may require cocrystals with a high solubility advantage over drug (SA = S_CC/S_D), but these may have limited potential to sustain drug supersaturation. Thus, we propose a twofold approach to mitigate the risk of drug precipitation by optimizing thermodynamic (SA) and kinetic factors (nucleation inhibitors). This risk can be evaluated by considering the cocrystal SA and drug dose/solubility ratio (D_0D = C_dose/S_D), which in tandem represent the maximum theoretical supersaturation that a cocrystal may generate, the driving force for drug precipitation, and the potential for dose-/solubility-limited absorption. cocrystals with SA and D_0D values above critical supersaturation are prone to rapid precipitation, often negating their utility as a solubility enhancement tool. This work presents a mechanistic approach to controlling the dissolution-supersaturation-precipitation behavior of cocrystal systems, whereby relationships between SA, D_0D, and the drug-solubilizing power of surfactants (SP_D = S_D,T/S_D,aq) are used to fine-tune cocrystal-inherent supersaturation by rational additive selection. Experimental results with danazol-vanillin cocrystal demonstrate how SA, D_0D, and SP_D are key thermodynamic parameters to understanding the kinetic cocrystal behavior and how the risks of cocrystal development may be mitigated through the mechanistic formulation design.

Cocrystallization: Cutting Edge Tool for Physicochemical Modulation of Active Pharmaceutical Ingredients

Cocrystallization is a widely accepted and clinically relevant technique that has prospered very well over the past decades to potentially modify the physicochemical properties of existing active pharmaceutic ingredients (APIs) without compromising their therapeutic benefits. Over time, it has become an integral part of the pre-formulation stage of drug development because of its ability to yield cocrystals with improved properties in a way that other traditional methods cannot easily achieve. Cocrystals are solid crystalline materials composed of two or more than two molecules which are non-covalently bonded in the same crystal lattice. Due to the continuous efforts of pharmaceutical scientists and crystal engineers, today cocrystals have emerged as a cutting edge tool to modulate poor physicochemical properties of APIs such as solubility, permeability, bioavailability, improving poor mechanical properties and taste masking. The success of cocrystals can be traced back by looking at the number of products that are getting regulatory approval. At present, many cocrystals have obtained regulatory approval and they successfully made into the market place followed by a fair number of cocrystals that are currently in the clinical phases. Considering all these facts about cocrystals, the formulation scientists have been inspired to undertake more relevant research to extract out maximum benefits. Here in this review cocrystallization technique will be discussed in detail with respect to its background, different synthesis approaches, synthesis mechanism, application and improvements in drug delivery systems and its regulatory perspective.

Protein X-ray Crystallography and Drug Discovery

With the advent of structural biology in the drug discovery process, medicinal chemists gained the opportunity to use detailed structural information in order to progress screening hits into leads or drug candidates. X-ray crystallography has proven to be an invaluable tool in this respect, as it is able to provide exquisitely comprehensive structural information about the interaction of a ligand with a pharmacological target. As fragment-based drug discovery emerged in the recent years, X-ray crystallography has also become a powerful screening technology, able to provide structural information on complexes involving low-molecular weight compounds, despite weak binding affinities. Given the low numbers of compounds needed in a fragment library, compared to the hundreds of thousand usually present in drug-like compound libraries, it now becomes feasible to screen a whole fragment library using X-ray crystallography, providing a wealth of structural details that will fuel the fragment to drug process. Here, we review theoretical and practical aspects as well as the pros and cons of using X-ray crystallography in the drug discovery process.

Cocrystal Solubility Advantage Diagrams as a Means to Control Dissolution, Supersaturation, and Precipitation

Cocrystals are often more soluble than needed and pose unnecessary risks for precipitation of less soluble forms of the drug during processing and dissolution. Such conversions lead to erratic cocrystal behavior and nullify the cocrystal solubility advantage over parent drug (SA = Scocrystal/Sdrug). This work demonstrates a quantitative method for additive selection to control cocrystal disproportionation based on cocrystal solubility advantage (SA) diagrams. The tunability of cocrystal SA is dependent on the selective drug-solubilizing power of surfactants (SPdrug = (ST/Saq)drug). This cocrystal property is used to generate SA-SP diagrams that facilitate surfactant selection and provide a framework for evaluating how SA influences drug concentration-time profiles associated with cocrystal dissolution, drug supersaturation, and precipitation (DSP). Experimental results with indomethacin-saccharin cocrystal and surfactants (sodium lauryl sulfate, Brij, and Myrj) demonstrate the log-linear relationship characteristic of SA-SP diagrams and the dependence of σmax and dissolution area under the curve (AUC) on SA with characteristic maxima at a threshold supersaturation where drug nucleation occurs. This approach is expected to streamline cocrystal formulation as it facilitates additive selection by considering the interplay between thermodynamic (SA) and kinetic (DSP) processes.