Exploration of surface tension measurement methods for pharmaceutical excipients

Surface tension is a crucial functional indicator for various classes of pharmaceutical excipients, as highlighted in both the Pharmacopoeia of the People's Republic of China (ChP) < 9601 Guidelines for Functionality-related Characteristics of Pharmaceutical Excipients > and the United States Pharmacopoeia (USP) < 1059 Excipient Performance >. However, there are few systematic studies on surface tension measurement of pharmaceutical excipients, resulting in a lack of stable parameter support in practical applications. In this study, we aim to fill this gap by exploring three different methods for measuring surface tension. These methods were carefully developed taking into account the actual measurement process and statistical theory, thus ensuring their applicability and reliability. Through comparative analyses, we have identified the most suitable measurement methods for different classes of pharmaceutical excipients. In addition, this paper describes the surface adsorption behavior of various excipients. Therefore, this study provides valuable guidance for the determination of surface tension and the study of surface adsorption behavior, which lays the foundation for further comprehensive research in the field of surface tension of pharmaceutical excipients and the improvement of general pharmacopoeia specification.

Analysis of environmental biodegradability of cellulose-based pharmaceutical excipients in aqueous media

Pharmaceutical cellulosic polymers will inevitably reach natural water systems if they are not removed after entering wastewater. Biodegradation of organic chemicals in sewage or in the aquatic environment is an important removal mechanism. In this study, we investigated the environmental biodegradation of 14 cellulose derivatives commonly utilized as pharmaceutical excipients using three different test systems that are based on the closed bottle test (OECD 301D) and the manometric respirometry test (OECD 301F). For the different cellulose derivatives tested, we observed varying degrees of biodegradation ranging from 0 to 20.4 % chemical oxygen demand (COD). However, none met the criteria for classification as 'readily biodegradable'. In addition, 10 out of 14 cellulose derivatives and/or their possible transformation products formed during the experiments, may exhibit possible toxic inhibitory effects on the inoculum. This includes one or several derivatives of hydroxy propyl methyl cellulose, hydroxy propyl cellulose, methyl cellulose, ethyl cellulose, and hydroxy ethyl cellulose. Based on the results obtained, we have developed a graded classification score ('traffic light system') for excipient biodegradation. This could help streamline the assessment and classification of cellulose derivatives concerning risk of persistence and potential adverse environmental effects, thereby assisting in the prioritization of more favorable compounds. In the long term, however, excipients should be designed from the very beginning to be biodegradable and mineralizable in the environment ('benign by design').

Accelerated blood clearance of PEGylated nanoparticles induced by PEG-based pharmaceutical excipients

PEGylated nanomedicines have been extensively developed and applied to cancer therapy. However, the antitumor efficacy of these nanoparticles is hampered by the accelerated blood clearance (ABC) effect caused by anti-PEG antibodies in vivo. There is still limited understanding about the cause of pre-existing anti-PEG antibodies in the human body. Herein, we discovered that PEG-based pharmaceutical excipients, commonly used in clinical and daily settings, could induce anti-PEG antibodies in vivo and lead to considerable potential clinical impacts on pharmacokinetics and pharmacodynamics of PEGylated nanoparticles. Specifically, we investigated the ability of poloxamer 188 (F68) and poloxamer 407 (F127), the two most frequently used PEG-based pharmaceutical excipients, to elicit the production of anti-PEG antibodies and influence the pharmacokinetics of PEGylated nanoparticles, with PEGylated liposome nanoparticles (L-NPs) as a model. Anti-PEG IgG and IgM levels were significantly boosted 3.8- and 32.2-fold, respectively, after pre-injection with F68, leading to rapid clearance of subsequently injected L-NPs from circulation due to the capture by neutrophils and monocytes. However, pre-injection of F127 did not induce the production of anti-PEG IgG, although there was a 7.7-fold increase in IgM level, which resulted in minimal effect on circulation time of L-NPs. Furthermore, the potential clinical impacts of F68 and F127 were further inspected for PEGylated liposomal doxorubicin (PLD). It was found that administering F68 prior to treatment led to over a one-third decrease in the antitumor effectiveness of PLD, while F127 had a negligible impact. Our study elucidates the mechanism by which PEG-based pharmaceutical excipients influence the effectiveness of PEGylated nanomedicines. It also highlights the significance of considering the potential for an ABC effect induced by PEG-based pharmaceutical excipients in patients.

Application of co-precipitated glutinous rice starch as a multifunctional excipient in direct compression tablets

Two key properties of excipients for inclusion in direct compression tablets are flowability and compactibility. Glutinous rice starch (GRS) has poor flowability, which limits its use in direct compression tablets. This study aimed to create a multifunctional direct compression excipient (filler binder disintegrant) with improved flowability from GRS by the co-precipitation method. The physicochemical and pharmaceutical properties of the co-precipitated GRS (cpGRS) were investigated. The optimum conditions for producing cpGRS (0.43 M sodium hydroxide solution, 7.09% PVP K30, 14.02% calcium carbonate, 95 min of mixing time and pH of 6.97) resulted in 68.80% yield, fair to good flowability, acceptable tablet strength, and fast disintegration. The FT-IR spectra of cpGRS showed no significant shifts in the key peaks, which indicates that there was an absence of chemical interactions within cpGRS. X-ray diffractograms also showed no significant changes, indicating that the GRS granules, calcium carbonate, and PVP K30 components remained unaltered during co-precipitation. cpGRS also demonstrated a dilution capacity of 50% when paracetamol was used as model drug. When cpGRS was combined with domperidone or propranolol hydrochloride it showed a better deformation capability than the physical mixtures. Although cpGRS was sensitive to lubricant, the hardness and tensile strength were higher than common strength for general purpose use in tablets. When compared to the physical mixture, pregelatinized starch and directly compressible calcium carbonate, the results showed that cpGRS tablets of both model drugs passed the friability test, demonstrated the best disintegration property, provided the fastest and highest drug release profile for propranolol, and improved the drug release profile for domperidone. For propranolol-cpGRS tablets, dissolution medium at different pH did not affect the dissolution profile. For domperidone-cpGRS tablets, the pH of dissolution medium did affect the dissolution profile of the tablets. This was according to the API solubility. These results reveal that cpGRS is an excellent multifunctional i.e., filler, binder, and disintegrant excipient suitable for direct compression tablets. The main component is natural. The preparation method is simple, quick, and efficient. This method does not produce harmful waste and requires only basic equipment, and affordable reactants and devices.

Technology development to evaluate the effectiveness of viscosity reducing excipients

Addition of pharmaceutical excipients is a commonly used approach to decrease the viscosity of highly concentrated protein formulations, which otherwise could not be subcutaneously injected or processed. The variety of protein-protein interactions, which are responsible for increased viscosities, makes a portfolio approach necessary. Screening of several excipients to develop such a portfolio is time and money consuming in industrial settings. Responsible protein-protein interactions were investigated using the interaction parameter k_D obtained from dynamic light scattering measurements in the studies presented herein. Together with in-silico calculated excipient parameter, k_D could be used as a screening tool accelerating screening and formulation development as k_D is suitable to high-throughput formats using small quantities of protein and low concentrations. A qualitative correlation between k_D and high-concentration viscosity behavior could be shown in our case.

Powder flow from an intermediate bulk container - Discharge predictions and experimental evaluation

Powders are usually dispensed, blended, and transferred between different manufacturing steps in so-called Intermediate Bulk Containers (IBCs), and discharge from an IBC plays a critical role in the ability to manufacture high-quality tablets. To better understand IBC discharge, the flow behavior of selected excipients was comprehensively characterized using a number of techniques including the Hausner ratio/Carr's index, Erweka flow test, FlowPro flow test, shear test and wall friction test as well as FT4 powder rheometer experiments. Jenike's hopper design methodology was then used to predict the minimum non-arching outlet diameter and the mode of flow. Furthermore, the discharge rate from an IBC was predicted using a simple model that takes into account gravity and aerodynamic drag. The predictions were experimentally verified by measuring the discharge rate from a 20 L IBC using five commonly-used excipients. The small-scale Erweka flow test provided the best prediction of the full-scale IBC discharge experiment. Furthermore, a simple model that relied only on the particle size of the material and the diameter of the discharge opening was found to predict the IBC discharge rate remarkably well.

Pharmaceutical Excipients and Drug Metabolism: A Mini-Review

Conclusions from previously reported articles have revealed that many commonly used pharmaceutical excipients, known to be pharmacologically inert, show effects on drug transporters and/or metabolic enzymes. Thus, the pharmacokinetics (absorption, distribution, metabolism and elimination) of active pharmaceutical ingredients are possibly altered because of their transport and metabolism modulation from the incorporated excipients. The aim of this review is to present studies on the interaction of various commonly-used excipients on pre-systemic metabolism by CYP450 enzymes. Excipients such as surfactants, polymers, fatty acids and solvents are discussed. Based on all the reported outcomes, the most potent inhibitors were found to be surfactants and the least effective were organic solvents. However, there are many factors that can influence the inhibition of CYP450, for instance type of excipient, concentration of excipient, type of CYP450 isoenzyme, incubation condition, etc. Such evidence will be very useful in dosage form design, so that the right formulation can be designed to maximize drug bioavailability, especially for poorly bioavailable drugs.

Spray-dried bacterial cellulose nanofibers: A new generation of pharmaceutical excipient intended for intestinal drug delivery

Defibrillation of bacterial cellulose by ultra-refining was efficient to release nanofibers (BCNF) which were spray dried with the matrices formers mannitol (MN), maltodextrin or hydroxypropylmethylcellulose. The best microsystem comprised the association of BCNF and MN, so the selected microparticles were loaded with diclofenac sodium or caffeine. Depending on the proportion of BCNF, the nanofibers collapse promoted by spray drying can occur onto surface or into microparticles core, leading to different release behaviors. Samples showed pH-dependent drug release, so the microsystem developed with the lowest BCNF concentration showed important trend to gastroresistance. Caffeine was spray dried as a free drug and for this reason it was devoid of any control over release rates. The set of results showed BCNF can be considered an interesting and potential pharmaceutical excipient for lipophilic drugs. Beyond that, BCNF association with MN can lead to novel enteric drug delivery systems based on natural polymers.

Delayed Hypersensitivity Reactions Caused by Drug Excipients: A Literature Review

The European Medicines Agency (EMA) defines excipients as the constituents of a pharmaceutical form apart from the active substance. Delayed hypersensitivity reactions (DHRs) caused by excipients contained in the formulation of medications have been described. However, there are no data on the prevalence of DHRs due to drug excipients. Clinical manifestations of allergy to excipients can range from skin disorders to life-threatening systemic reactions. The aim of this study was to perform a literature review on allergy to pharmaceutical excipients and to record the DHRs described with various types of medications, specifically due to the excipients contained in their formulations. The cases reported were sorted alphabetically by type of medication and excipient, in order to obtain a list of the excipients most frequently involved for each type of medication.

Immediate Hypersensitivity Reactions Caused by Drug Excipients: A Literature Review

The European Medicines Agency defines excipients as the constituents of a pharmaceutical form apart from the active substance. Immediate hypersensitivity reactions (IHRs) caused by excipients contained in the formulation of medications have been described. However, there are no data on the prevalence of IHRs due to drug excipients. Clinical manifestations of allergy to excipients can range from skin disorders to life-threatening systemic reactions. The aim of this study was to review the literature on allergy to pharmaceutical excipients and to record the IHRs described with various types of medications, specifically reactions due to the excipients contained in their formulations. The cases reported were sorted alphabetically by type of medication and excipient in order to obtain a list of the excipients most frequently involved for each type of medication.

Antioxidant properties of probucol released from mesoporous silica

Antioxidants play a vital role in scavenging reactive oxygen species (ROS) produced by the reduction of molecular oxygen from various cellular mechanisms. Under oxidative stress, an increase in the levels of ROS overwhelms the antioxidant response, causing oxidative damage to biological molecules, and leading to the development of various diseases. Drug compounds with potent antioxidant properties are typically poorly water soluble and highly hydrophobic. An extreme case is Probucol (PB), a potent antioxidant with reported water solubility of 5 ng/ml, and oral bioavailiability of <10%. In this study, PB was loaded in mesoporous silica at various drug loadings to understand the changes to the physical properties of the loaded drug, and it's in vitro drug release. Further in vitro studies were conducted in endothelial and microglia cell models to compare the free radical scavening efficiency of ascorbic acid, PB, and PB release from mesoporous silica particles. Out of the three different mesostructured particles studied, the maximum loading of PB was achieved for large pore mesoporous particles (SBA-15) at 50 wt% drug loading, before complete pore filling was observed. For all materials, loadings above complete pore filling resulted in the recrystallization of PB on the external surface. In vitro drug release measurements showed a rapid dissolution rate at low drug loadings compared to a bimodal release profile of amorphous and crystalline drug at higher drug loadings. PB loaded in mesoporous particle was shown to enhance the antioxidant response to extracellular ROS in the endothelial cell line model, and to intracellular ROS in the microglia cell model. Our results indicate that the antioxidant properties of PB can be significantly improved by using mesoporous silica as a delivery vehicle.

Pharmaceutical excipients properties and screw feeder performance in continuous processing lines: a Quality by Design (QbD) approach

Screw feeder performance is a critical aspect in continuous manufacturing processes. Pharmaceutical excipients, such as mannitol, microcrystalline cellulose, lactose monohydrate, and anhydrous dibasic calcium phosphate can present problems in ensuring a continuous stable feed rate due to their sub-optimal flow properties. In alignment with Quality by Design (QbD) goals, the aim of this work was to identify and explain critical sources of variability of some powder excipients delivery by screw feeding, in particular to continuous processing lines. Pharmaceutical excipients with a wide range of material properties were selected, and the impact of their flow and density properties on screw feeder performance was investigated. The analysis of the powder conveying by the screws was performed at different hopper fills and different screw speeds. A multivariable model involving bulk density (CBD) and parameters from FT4 dynamic downwards testing (SI) and dynamic upwards testing (SE) explained 95.7% of excipients feed rates (p < .001). The study gathers valuable information about the screw feeder performance and input materials properties that can help process understanding and QbD-based development of solid dosage forms in continuous processing lines.

Influence of breast cancer resistance protein and P-glycoprotein on tissue distribution and excretion of Ko143 assessed with PET imaging in mice

Ko143 is a reference inhibitor of the adenosine triphosphate-binding cassette (ABC) transporter breast cancer resistance protein (humans: ABCG2, rodents: Abcg2) for in vitro and in vivo use. Previous in vitro data indicate that Ko143 binds specifically to ABCG2/Abcg2, suggesting a potential utility of Ko143 as a positron emission tomography (PET) tracer to assess the density (abundance) of ABCG2 in different tissues. In this work we radiolabeled Ko143 with carbon-11 (¹¹C) and performed small-animal PET experiments with [¹¹C]Ko143 in wild-type, Abcg2^(-/-), Abcb1a/b^(-/-) and Abcb1a/b^(-/-)Abcg2^(-/-) mice to assess the influence of Abcg2 and Abcb1a/b on tissue distribution and excretion of [¹¹C]Ko143. [¹¹C]Ko143 was extensively metabolized in vivo and unidentified radiolabeled metabolites were found in all investigated tissues. We detected no significant differences between wild-type and Abcg2^(-/-) mice in the distribution of [¹¹C]Ko143-derived radioactivity to Abcg2-expressing organs (brain, liver and kidney). [¹¹C]Ko143 and possibly its radiolabeled metabolites were transported by Abcb1a and not by Abcg2 at the mouse blood-brain barrier. [¹¹C]Ko143-derived radioactivity underwent both hepatobiliary and urinary excretion, with Abcg2 playing a possible role in mediating the transport of radiolabeled metabolites of [¹¹C]Ko143 from the kidney into urine. Experiments in which a pharmacologic dose of unlabeled Ko143 (10 mg/kg) was co-administered with [¹¹C]Ko143 revealed pronounced effects of the vehicle used for Ko143 formulation (containing polyethylene glycol 300 and polysorbate 80) on radioactivity distribution to the brain and the liver, as well as on hepatobiliary and urinary excretion of radioactivity. Our results highlight the challenges associated with the development of PET tracers for ABC transporters and emphasize that inhibitory effects of pharmaceutical excipients on membrane transporters need to be considered when performing in vivo drug-drug interaction studies. Finally, our study illustrates the power of small-animal PET to assess the interaction of drug molecules with membrane transporters on a whole body level.