A feasibility study on direct assay of an aqueous formulation by chiral supercritical fluid chromatography (SFC)

Supercritical fluid chromatography (SFC) has gained considerable importance in the area of Separation Science in pharmaceutical analysis over the past few years. The synthesis of chiral compounds is of particular significance in the pursuit of new drug entities. SFC is rapidly replacing high performance liquid chromatography (HPLC) in many pharmaceutical and biotechnological companies as the standard screening and method development tool for chiral compounds. Analysis of pharmaceutical formulations of research compounds is an area where SFC is recently being explored as a possible alternate or complementary technique to HPLC in limited scope. A feasibility study was carried out to perform direct assay of a chiral drug compound AZM in 100% aqueous formulations by SFC. The results indicated that this approach has the potential to significantly reduce the typical sample processing time prior to analysis. The method was reproducible, linear over a wide dynamic range, and sensitive enough to detect the minor enantiomeric impurity in the chiral drug compound investigated here. Further application will be pursued for other research compounds in the future to illustrate the broader applicability of this approach.     

In Vitro Screening Methods To Assess the Potential of In Vivo Precipitation of Injectable Formulations upon Intravenous Administration

In vivo precipitation of injectable formulations upon intravenous administration is a major concern in formulation development. In this work, two in vitro screening tools, static dilution and dynamic injection, are developed to assess the potential of in vivo precipitation of active pharmaceutical ingredients from injectable formulations upon intravenous administration. Nine model injectable formulations are studied. These include marketed formulations as well as formulations from Merck programs. Results from these models are compared with reports of precipitation from product labels, the Physicians Desk Reference, and literature reports. Good correlation is observed between results from the static dilution and dynamic injection models. The in vitro data correlates well with precipitation reported during clinical evaluations and animal experiments. The importance of protein in dilution medium, prototype formulations for screening studies, and optical microscopy for studying phase behavior is demonstrated. This work demonstrates the utility of using these models as a valuable screen during injectable formulation development. LAY ABSTRACT: In vivo precipitation of injectable formulations upon intravenous administration is a major concern in formulation development. Although animal models are routinely used for this purpose, they require strict protocol and are expensive. Furthermore, their results are far from ideal. This work describes the development of two in vitro screening tools, static dilution and dynamic injection, to assess the potential of in vivo precipitation of active pharmaceutical ingredients from injectable formulations upon intravenous administration. The utility of using these models as a valuable screen during injectable formulation development is demonstrated through the use of several model compounds.     

Rapid screening of antioxidants in pharmaceutical formulation development using cyclic voltammetry--potential and limitations

Cyclic voltammetry (CV) is a unique technique for the electrochemical characterization of compounds by providing their oxidation/reduction potentials. This technique is widely used in evaluating antioxidants in the oil, food, diagnostic and agricultural industries; however, CV is rarely used in the development of pharmaceutical formulations. This review briefly describes the basic principles of CV and its application in other industries along with the potential and limitations of CV in the rapid evaluation of antioxidants in pharmaceutical formulations. An extensive survey of the literature shows that there is a good correlation between the oxidation potentials of various antioxidants and their antioxidant efficiency. In conclusion, CV should be useful in the development of pharmaceutical formulations where a small group of the preferred antioxidants is rapidly identified. This small group of the most preferred antioxidants can then be employed in a conventional drug stability study thereby providing a rapid approach for the selection of the most suitable antioxidant for a pharmaceutical formulation.     

Advanced screening assays to rapidly identify solubility-enhancing formulations: high-throughput, miniaturization and automation

Development of solubility-enhancing formulations for poorly water-soluble compounds always poses a challenge. Conventional formulation screening assays are potentially time-consuming and labor-intensive and, moreover, require a large amount of a compound; they are not ideal when compound availability and testing time are limited. In recent years, in-vitro screening assays that are rapid, inexpensive, minimally labor-intensive, and require only small quantities of a compound have become available. These advanced assays allow high-throughput automation, miniaturization, and parallel processing, thereby enabling scientists to rapidly identify solubility-enhancing formulations with milligram or sub-milligram quantities of an active pharmaceutical ingredient (API). This article reviews these assays for rapidly screening the aqueous solubility of lead compounds and the solubility-enhancing formulations with limited quantities of API.     

Miniaturized Assay for Solubility and Residual Solid Screening (SORESOS) in Early Drug Development

Purpose The aim was to develop a miniaturized method for solubility and residual solid screening of drug compounds in aqueous and non-aqueous vehicles in early drug development. Methods Different crystal modifications of caffeine, carbamazepine, and piroxicam were added into 96-well filter plates and solubility was determined in 100 μl of 17 pharmaceutical vehicles. After filtration, drug concentration was determined by Ultra Performance Liquid Chromatography™ (UPLC). Residual solid drug in the filter plates was analyzed by high-throughput (HT) transmission X-ray Powder Diffraction (XRPD). Results HT XRPD analysis revealed solid form conversions of all compounds during solubility determination, e.g., formation of hydrates in aqueous vehicles (caffeine, carbamazepine, piroxicam) or conversion of a metastable crystal form to the stable form (caffeine). Drug solubility was strongly dependent on the crystal modifications formed during the solubility assay. Conclusions The new assay allows the simultaneous, small scale screening of drug solubility in various pharmaceutical vehicles and identification of changes in solid form. It is useful for the identification of formulations and formulation options in non-clinical and clinical development.     

In vitro hemolysis: guidance for the pharmaceutical scientist

Pharmaceutical excipients are commonly incorporated into parenteral formulations to increase solubility and stability of active pharmaceutical ingredients. The biocompatibility of these excipients is an important consideration during formulation development. Despite the importance of hemolytic potential of parenteral formulations, there is considerable contradictory information in the literature related to the hemolytic potential of various excipients. The hemolytic potential of various formulation vehicles in dog, rabbit, and human blood by means of an in vitro hemolysis assay is compared. The selected formulation vehicles are found in currently marketed drug products. The guidance presented here considers formulations with a hemolysis value of <10% to be nonhemolytic while values > 25% to be at risk for hemolysis.     

Colorimetric Polymer Films for Predicting Lipid Interactions and Percutaneous Adsorption of Pharmaceutical Formulations

Purpose  To develop and demonstrate a rapid and simple colorimetric film assay for evaluating lipid interactions of pharmaceutical compounds and gel formulations. Methods  The colorimetric assay comprises glass-supported films of phospholipids and polydiacetylene, which undergo visible and quantifiable blue–red transformations induced by interactions with amphiphilic molecules applied in very small volumes on the film surface. The color transitions are recorded by scanning of the films, and quantified through a simple image analysis algorithm. Results  We show that pharmaceutical molecules and gel formulations induce blue–red transformations after short incubation with the lipid/polydiacetylene (PDA) films. Colorimetric dose–response curves exhibit dependence upon the lipid affinity and extent of membrane binding of the pharmaceutical compounds examined. The colorimetric lipid/PDA film assay was employed for distinguishing the contributions of individual molecular components within gel formulations. Conclusions  The colorimetric data yield insight into the degree of lipid binding of the molecules tested. The film assay is particularly advantageous for analysis of semi-solid (gel or lotion) formulations, elucidating the lipid interaction characteristics of specific molecular components within the mixtures. The new colorimetric film assay constitutes a generic, rapid, and easily applicable platform for predicting and screening interactions of pharmaceutical compounds and complex formulations with lipid barriers. Izek Ben-Shlush and Roman Volinsky contributed equally.     

Quantification of Silicone Oil and Its Degradation Products in Aqueous Pharmaceutical Formulations by 1H-NMR Spectroscopy

During the past years, there has been an increasing focus on the presence of silicone oil as a contaminant in pharmaceutical formulations kept in prefilled syringes (PFSs). As the PFSs are coated on the inner wall with silicone oil (polydimethylsiloxane), there is a potential risk that the oil can migrate from the inner surface of the primary packing material into the aqueous solution. Several studies have demonstrated that presence of silicone oil as droplets in a high-concentrated protein formulation can cause protein aggregation. Hence, because the use of silicone-coated primary packing material for protein formulations are increasing, the call for an easy and quantitative method for determination of silicone oil and its degradation products in pharmaceutical formulations is therefore needed. Several analytical techniques have in the past been developed with the aim of detecting the presence of silicone oil and degradation products hereof. Most of these methods require hydrolyzation, derivatization, and extraction steps followed by, for example, gas chromatography-mass spectrometry analysis. Applying these methods can cause a loss in detection or an overestimation of the hydrolytic degradation products of silicone oil, that is, trimethylsilanol and dimethylsilanediol. The 2 silanols are highly hydrophilic and prefers the aqueous environment. Analysis of an aqueous formulation obtained from a PFS by ¹H-NMR spectroscopy provides data about the content and levels of silicone oil and the 2 silanols even in levels below 10 ppm. The ¹H-NMR method offers an easy and direct, quantitative measurement of samples intended for clinical use and samples kept at elevated temperature for a prolonged time (i.e., stability studies). The result of the study presented here showed dimethylsilanediol to be the main silicone compound present in the aqueous formulation when kept in baked-on PFSs. The degradation product dimethylsilanediol, in full accordance with expected hydrolytic degradation of silicone oil, increased during storage and with elevated temperature. In addition, the method can be applied to aqueous samples where polydimethylsiloxane has been added as, for example, the major constituent of antifoam.     

Determination of propylene carbonate in pharmaceutical formulations using liquid chromatography

A stability-indicating reversed-phase high-performance liquid chromatographic method using a refractive index detector is described for the determination of propylene carbonate in pharmaceutical formulations. Good precision and accuracy of the method was demonstrated using an aqueous formulation. This method is also applicable to an anhydrous formulation.     

Prediction of eye irritation potential of surfactant-based rinse-off personal care formulations by the bovine corneal opacity and permeability (BCOP) assay

Evaluation of eye irritation potential is a routine part of product safety testing. Many companies have elected to use in vitro methods for this evaluation. We used the bovine corneal opacity and permeability (BCOP) assay for the prediction of the eye irritation potential of surfactant-based rinse-off personal care formulations in this study because of its positive performance in previous studies (1), and its potential to measure depth of injury through histological evaluation. The BCOP uses isolated corneas maintained in short-term organ culture and measures changes in opacity and epithelial barrier integrity (as determined by fluorescein passage through the cornea). Surfactants (anionic and nonionic) used in personal care formulations induce only small increases in direct opacity but the degree of epithelial damage is reflected in permeability measurement (OD490). The permeability measurement is the primary endpoint for this class of products. Marketed liquid hand soap was selected as the benchmark due to extensive in vivo and market history data. Using the liquid hand soap, a 25% v/v aqueous dilution with a 30-minute exposure produced the optimal resolution. A series of products with known in vivo eye irritation scores were evaluated to establish a prediction model. Histological evaluation was used to compare the degree of tissue damage to the permeability scores. Based on the permeability scores and histological review, the testing protocol for a surfactant-based rinse-off personal care formulation was developed using a 25% v/v aqueous dilution, a 30-minute exposure, concurrent testing of the benchmark control, and use of permeability measurements as the endpoint for the evaluation of eye irritation potential.     

Parallel screening approach to identify solubility-enhancing formulations for improved bioavailability of a poorly water-soluble compound using milligram quantities of material

In this article, we present a parallel experimentation approach to rapidly identify a solubility-enhancing formulation that improved the bioavailability of a poorly water-soluble compound using milligrams of material. The lead compound and a panel of excipients were dissolved in n-propanol and dispensed into the wells of a 96-well microtiter plate by a TECAN robot. Following solvent evaporation, the neat formulations were diluted with an aqueous buffer, and incubated for 24 h. The solubilization capacity of the excipients for the compound at 24 h (SC_24 h), was determined by HPLC, and compared with its solubility in the corresponding neat formulations determined by a bench-scale method. The ranking order of solubilization capacity of the five tested formulations for this compound by this microscreening assay is same as the ranking order of the compound solubility in the neat formulations. Several formulations that achieved the target aqueous solubility were identified using the screening method. One of the top formulations, an aqueous solution of the compound containing 20% Tween^® 80 by weight, increased the compound solubility from less than 2 μg/mL to at least 10 mg/mL. In a rat pharmacokinetic (PK) study, the Tween^® 80 formulation achieved 26.6% of bioavailability, a significant improvement over 3.4% of bioavailability for the aqueous Methocel^® formulation (p < 0.01). The results in the study suggest that this parallel screening assay can be potentially used to rapidly identify solubility-enhancing formulations for an improved bioavailability of poorly water-soluble compounds using milligram quantities of material.     

Physical stability of nonviral plasmid-based therapeutics

Nonviral, plasmid-based therapeutics are a new class of pharmaceutical agents that offer the potential to cure many diseases that are currently considered untreatable. While nonviral vectors have shown promise in clinical trials, their physical instability in liquid formulations represents a major barrier to the development of these agents as marketable products. While several different approaches have been used to improve the stability of liquid formulations, it is unclear whether aqueous suspensions can be rendered sufficiently stable to withstand the stresses associated with shipping and storage. Some studies have demonstrated the potential of frozen formulations to be stored for prolonged periods of time, however the potential for phase changes in frozen samples combined with the expense of maintaining the frozen state during shipping has stimulated an interest in developing dehydrated preparations. Although the stresses associated with dehydration are considerable, several studies have reported that sugars are capable of preserving the physical characteristics and transfection activity of nonviral vectors during acute lyophilization stress. This paper discusses the merits and drawbacks of the different approaches to preserving nonviral vectors, and identifies research areas in which more work is needed to develop stable formulations of plasmid-based therapeutics.     

Oral delivery of diclofenac sodium using a novel solid-in-oil suspension

The present work reports on a new pharmaceutical formulation for oral delivery of diclofenac sodium (DFNa), a non-steroidal anti-inflammatory drug (NSAID). Although DFNa itself is water-soluble at neutral pH, it was readily suspended in soybean oil via complex formation with an edible lipophilic surfactant and a matrix protein. The resulting solid-in-oil (S/O) suspension containing stably encapsulated DFNa in an oil phase markedly reduced the risks for gastrointestinal ulcers upon oral administration even at the LD(50) level in rats (ca. 50 mg/kg DFNa). In addition, plasma concentration of DFNa upon administration of an S/O suspension was comparable with that of the aqueous counterpart at the same DFNa dose. These results indicate the potential use of S/O suspensions as novel oil-based pharmaceutical formulations for oral delivery of water-soluble drugs without causing severe mucitis.     

Relationships between the modulus of elasticity and tensile strength for pharmaceutical drugs and excipients.

The relationship between the modulus of elasticity and tensile strength for a variety of pharmaceutical drugs and excipients has been explored as a means of generating algorithms for use in computer simulations and expert systems. From literature data two equations have been developed to enable the formulator, from knowledge of one property, to predict the other with a reasonable degree of accuracy. Such relationships are invaluable for use in computer simulation programs or formulation expert systems, enabling formulators to screen potential formulations quickly without the need for extensive experimental work.     

Development and effect of storage on the stability of enriched flavonoid fraction of Cecropia glaziovii-loaded PLGA nanoparticles

Abstract

Studies employing Cecropia glaziovii Snethl leaves have shown great potential in regard to their antiviral activity, mainly related to the phenolic compounds present in this species. The main goal of this work is to combine the therapeutic potential of this species with new technological strategies targeted at the development of an herbal nanoparticulate system for the preparation of a phytotherapeutic formulation. Poly (lactic-co-glycolic acid) nanoparticles containing the enriched flavonoid fraction of Cecropia glaziovii Snethl were developed through a study for the choice of preparation technique, amount of drug and surfactants used. These nanostructured systems were characterized by particle size, polydispersity, zeta potential, encapsulation efficiency and drug-loading capacity. A stability study of the formulations was conducted at room temperature over a period of 60 days. The optimal formulation that best fit the characteristics of the encapsulated material was determined. Sorbitan monooleate and the poloxamer 188 resulted in better colloidal stability, added to the organic and aqueous phases, respectively. These findings suggest that in the field of nanoparticles stability, it is important to evaluate the composition of the nanoparticulate system. This work highlights the importance of the optimization process, searching for a good formulation with suitable structural stabilization.     

Development,Characterization and In Vitro Antimicrobial Evaluation of Novel Flavonoids Entrapped Micellar Topical Formulations of Neomycin Sulfate

Flavonoids are the secondary metabolites widely used in pharmaceutical industries due to their several health benefits. Quercetin and rutin, well known flavonoids possesses various pharmacological properties but the constraints of poor aqueous solubility and impermeability across cell membranes restricts their use in formulation development. Moreover, the rising problem of antimicrobial resistance has also caused a serious threat to human life, thus demanding the urgent need of developing more effective antimicrobial formulations. In view of this, the present research work is focused on utilizing the most feasible flavonoid-surfactant concentrations obtained from the already reported physico-chemical analysis in developing an improved neomycin topical formulation through drug combinatorial approach. The formulations were subjected for assessment of physical parameters such as determination of pH, viscosity and spreadability. The drug release profile of the formulations was studied through different mathematical models. After evaluation of all the parameters, two best formulations (NQ-T2 [HE] and NR-T1 [HE]) were selected for antimicrobial evaluation studies against different bacterial and fungal clinical isolates. Among the two formulations, NQ-T2 [HE] showed excellent antibacterial activity against the bacterial strains while NR-T1 [HE] also exhibited promising results when compared with the standard formulations. Overall, this study represents a possible solution to enhance the antimicrobial efficacy of neomycin formulations by combining them with flavonoids through micelles assisted drug combination approach.     

Influence of Formulation,Receptor Fluid,and Occlusion,on in Vitro Drug Release from Topical Dosage Forms,Using an Automated Flow-Through Diffusion Cell

An automated flow-through diffusion cell apparatus was used for comparing the release rates of a naphthoic acid derivative, CD 271, from different topical formulations. The influence of the following parameters on CD 271 release from the formulations was investigated: receptor fluid composition, occlusion, weight of tested formulation, and dosage form type. The amount of tested formulation was shown to have no significant effect on the apparent release constant and lag time for an anionic oil-in-water emulsion and an aqueous gel. Occlusion affected drug release from the different dosage forms. Thus, occlusion increased CD 271 pharmaceutical availability for a lotion and a hydroalcoholic gel containing 0.1% of sol-ubilized drug. The release profile of CD 271 from the formulations was highly dependent on the receptor fluid composition. Drug release was dramatically enhanced with n-octanol as compared to an aqueous solution of surfactant. Using occlusive or nonocclusive procedures, CD 271 apparent release constant and lag time were found to be highly dependent on the type of tested formulation. The flow-through diffusion cell proposed in the present study allows an accurate comparison of drug release characteristics from prototype topical formulations and therefore represents a valuable tool for formulation research or quality control process.     

Developing early formulations: practice and perspective

Early formulations are prepared mostly for drug compounds at both discovery and preclinical stages and are used to animals via various routes such as oral and intravenous dosing. They serve the purpose of evaluating these compounds on a broad range of pharmaceutical interests, notably pharmacology (activity/efficacy), pharmacokinetics (PK), and toxicology. It is estimated that approx. 40% of all drug compounds discovered have certain delivery limitations due to poor solubility or poor bioavailability. This brings tremendous challenges to the scientists working in the field of early formulations. This study intends to cover a broad spectrum of early formulations including basic aspect and development aspect. On basic aspect, it summarized early formulation study purpose, objectives, dosing route, animal species, etc. It then evaluated a variety of dosage forms and solubility enhancement approaches including various solutions, suspensions, lipid-based formulations, solid dispersions, etc. On development aspect, this study broadly reviewed literatures and current practice in the field, the issues and challenges. It offered authors' own approaches and strategies including general development schemes for oral and for i.v., recommended excipient use range for oral and for i.v., experimental procedures for vitro serial dilution method, for kinetic solubility, etc. The study also discussed a number of case analyses and emphasized scientific rationales and experimental approaches in each of them. The study concluded with authors' summary and some comments on early formulation practice, thoughts and perspectives on its future trend. The study is a mixture of literature review and investigational research. It provides many useful information, practical procedures, and recommendations. It is expected that the study will fill the void of literature of such kind, and provide direct benefit to everyday practitioners in the field.