Formulation and Evaluation of a Novel Oral Oil-Based Suspension Using Micro-environmental pH-Modifying Solid Dispersion

Evaluation of the bioavailability of a Tamiflu taste-masking pediatric formulation using a juvenile pig model and LC-MS/MS

Aim: To improve the palatability and increase compliance in pediatric patients, different taste-masking technologies have been evaluated to support the NIH Pediatric Formulation Initiative.Methods: This bioavailability approach combined a juvenile porcine model which represented the pediatric population, and an advanced UHPLCMS/MS method. Juvenile pigs were administered with either commercial Tamiflu or its taste-masking formulation and plasma samples were obtained from 0 to 48 h. The mass spectrometer was operated in positive mode with electrospray ionization.Results: The bioavailability profiles were not significantly different between the two formulations which demonstrated that taste-masking by forming an ionic complex was a promising approach for formulation modification.Conclusion: The pre-clinical study revealed a promising model platform for developing and screening taste-masking formulations.

Exploring paediatric oral suspension development: Challenges, requirements, and formulation advancements

Oral suspension is the most preferred dosage form for the paediatric population because of the difficulties related to solid medications, such as the swallowing limitations, bitter taste, and poor oral bioavailability, which can cause serious impairment to attain a successful treatment. Given the importance of successful therapies, there is a need for safe and effective commercially-available paediatric oral suspension and their characterization. For the latter, it is important to identify safe excipients and preservatives. The paediatric group is a diverse category which includes infants and teenagers, with major pharmacokinetics and pharmacodynamics differences, mainly because of physiological and behavioral variations. Therefore, finding a single formulation for paediatric population remains a challenge, as well asthe formulation of stable-in-time suspension. In addition, drug's dissolving characteristic and permeation, are the main determinants for oral absorption, which are closely related to drug release kinetics from the pharmaceutical form. In this context, drug release profile is an important and limiting step in oral bioavailability, particularly for BCS class II drugs; thus, it is possible to increase bioavailability and minimize adverse effects by changing the release rate of such drugs. This review covers all the aspects for paediatric oral suspension development, and analyses the considerations for excipients selection as a crucial task for effectively choosing a safe and effective pharmaceutical form and correctly dosing paediatric patients.

Enabling a novel solvent method on Albendazole solid dispersion to improve the in vivo bioavailability

Albendazole, a vital medication endorsed by the World Health Organization for combating parasitic infections, encounters a challenge stemming from its low solubility, significantly impeding absorption and bioavailability. Albendazole has near-insolubility in most organic solvents, so the solid dispersions of albendazole were predominantly using the fusion method. However, the solvent method could offer the advantage of achieving molecular-level mixing homogeneity. In this investigation, we incorporated the pH adjustment to prepare albendazole solid dispersion using a solvent method, which utilizes trace amounts of HCl in methanol, yielding notably enhanced albendazole solubility. Subsequently, carriers such as PEG6000/Poloxamer 188 (PEG: polyethylene glycol) and PVP K30/Poloxamer 188 (PVP: polyvinylpyrrolidone) were employed to create albendazole solid dispersions. Comprehensive characterization through dissolution rate analysis, PXRD (Powder X-ray diffraction), SEM (Scanning electron microscopy), DSC (differential scanning calorimetry), and pharmacokinetic (PK) studies in mice and rats was conducted. The findings indicate that the solid dispersion effectively transforms the crystalline state of albendazole into an amorphous state, resulting in significantly enhanced in vivo absorption and a 5.9-fold increase in exposure. Besides, the exposure increased 1.64 times of commercial albendazole tablets. Notably, PEG6000/Poloxamer 188 and PVP K30/Poloxamer 188 solid dispersions exhibited superior dissolution rates and pharmacokinetic profiles compared to commercially available albendazole tablets.

Enteric and hydrophilic polymers enhance dissolution and absorption of poorly soluble acidic drugs based on micro-environmental pH-modifying solid dispersion

The oral bioavailability of poorly water-soluble active pharmaceutical ingredient (API) is often inadequate for the desired therapeutic effect. Micro-environmental pH-modifying solid dispersion (micro pHm SD) is an effective method for enhancing the dissolution of pH-dependent soluble APIs. However, erratic bioavailability of these drugs was often found when the micro pHm SD of the drugs was orally administrated and passed through the gastrointestinal tract. Because the added alkalizer in micro pHm SD could be neutralized by the acid in the stomach, as a result not enough alkalizer is left to form alkaline micro-environment around the drug in the intestine, leading to poor dissolution and bioavailability of API. Enteric polymers are applicable materials for site-specific drug delivery that are insoluble in gastric tract but soluble in the intestine targeted for drug release. In this study, a poorly water-soluble model drug, toltrazuril (TOL), was prepared as enteric micro pHm SD with enteric, hydrophilic polymers and alkalizer. The surface of enteric micro pHm SD tablets staining and alkalizer protection test in the acid dissolution medium qualitatively and quantitatively confirmed the protective effects of the enteric polymer on the alkalizer. Dissolution studies revealed that the drug release from the enteric micro pHm SDs was improved significantly compared with micro pHm SD with no enteric polymer. The pH-dependent solubility of enteric polymer had effects on the dissolution of APIs from the SDs in neutral medium. Enteric micro pHm SDs with higher proportion of enteric polymer showed higher C_max and dissolution rate of TOL. The physicochemical characterization and the molecular interaction between drug and matrix were analyzed by electron microscopy (SEM), differential scanning calorimetry (DSC), and fourier transform infrared spectroscopy (FTIR), finding that the formation of hydrogen bonds between TOL and matrix was helpful to promote dissolution of TOL. Ca(OH)₂-TOL-PVPk30-HPMCAS 8: 8: 18: 6 was determined as the most optimal enteric micro pHm SD, which significantly improved the bioavailability of TOL and its active metabolism (TOLSO, TOLSO₂) in pharmacokinetic study and could effectively reduce the irritation of the gastrointestinal mucosa caused by the alkalizer Ca(OH)₂ when the SD was orally administrated to rabbits. The present study demonstrates that formulating APIs with poor water solubility as enteric micro pHm SD is an effective method for protecting the alkalizer in SD and improving the dissolution of APIs and the bioavailability following oral administration.

Pharmacokinetics of toltrazuril and its metabolites after oral and parenteral administration of novel oil-based suspension based on micro-environmental pH-modifying solid dispersion in rabbits

Toltrazuril (TOL) is a broad-spectrum anticoccidial drug which is widely used in poultry and livestock. A novel oral suspension based on soybean oil-based TOL micro-environmental pH-modifying solid dispersion (micro pHm SD) and a novel injectable suspension based on white oil-based TOL micro pHm SD were developed, showing high physicochemical stability and high drug release in vitro with good histocompatibility. The present study is to evaluate the pharmacokinetic profiles of TOL and its major metabolites, e.g. toltrazuril sulfoxide (TOLSO) and toltrazuril sulfone (TOLSO₂) in rabbits following oral or subcutaneous administration with these two TOL SD suspensions. The plasma concentrations of TOL, TOLSO and TOLSO₂ were determined by high performance liquid chromatography (HPLC). Plasma concentration-time data were analyzed by a non-compartmental model analysis. The soybean oil-based TOL suspension after single oral administration at 20 mg/kg body weight (bw) significantly increased the plasma concentrations of TOL, TOLSO and TOLSO₂ compared with Baycox® 5 % suspension. Following subcutaneous administration of the white oil-based TOL suspension (20 mg/kg bw), TOL was well absorbed and metabolized more slowly to TOLSO and TOLSO₂, compared with oral administration, resulting in the significantly prolonged residence time in rabbits. The two suspensions significantly improved the relative bioavailability of TOL and its two metabolites, showing their potential usage in the control of coccidian in poultry and livestock.

A novel oil-based suspension of a micro-environmental, pH-modifying solid dispersion for parenteral delivery: Formulation and stability evaluation

The objective of this study was to evaluate a novel oil-based suspension as a potential parenteral drug delivery system for drugs with poor water solubility. Most of the new active pharmaceutical ingredients are weak acid or basic drugs with pH-dependent solubility. To limit this dependence, use of micro-environmental pH-modifying solid dispersions (micro pHm SD) has been proved to increase the bioavailability of these drugs. Toltrazuril (TOL), a weakly acidic drug with poor aqueous and pH-dependent solubility, was studied as a model drug. Recently, studies on TOL with focus on the parenteral injection are rarely to find in the literature. A novel parenteral oil-based TOL suspension was prepared containing TOL micro pHm SD (TSD) powders suspended in oil-based vehicles and the optimal formulation was screened. The stability of this formulation was assessed considering particle size distribution, settling volume ratio, redispersibility, thermal stability, and drug content. The optimized white oil-based TOL pHm SD suspension (W-TSDS) showed significant improved stability and shear-thinning behavior. In particular, fumed silica as suspending agent positively influenced the physical stability of the formulation. Furthermore, W-TSDS showed good injectability using 21 G needles and more rapid and sustained drug release compared to TSD powders in vitro. In the in vivo safety evaluation, W-TSDS showed good histocompatibility in rabbits injected subcutaneously or intramuscularly. We believe these findings provide an alternative choice of dosage form for the delivery of new active pharmaceutical ingredients.

A microcapsule oil dispersion for the controlled release of 1-methylcyclopropene in an open environment

1-Methylcyclopropene (1-MCP) is an important gaseous plant growth regulator. For its application as a gaseous pesticide, the plants with 1-MCP α-cyclodextrin microcapsule granules need to be enclosed in a sealed chamber. To provide a new spray formulation of 1-MCP for open environment application, herein, a novel 1-MCP microcapsule oil dispersion (1-MCP/MCOD) was prepared and characterized. It was found that 1-MCP could stay at higher concentrations for more than 36 hours during the controlled release experiment, and the SEM experiment showed good deposition of the 1-MCP/MCOD spray solution. In addition, the apple harvest application experiments showed that 1-MCP/MCOD could effectively prevent fruit drop at 3 μL L⁻¹ in an open environment. These results not only supply a new 1-MCP/MCOD kind of formulation for the flexible application of the 1-MCP gas in an open environment, but also show that this microcapsule oil dispersion formulation has significant potential in gaseous pesticide applications.

Formulation of 1-MCP/MOOD and controlled release process for application in the open environment.