Oseltamivir Phosphate–Amberlite™ IRP 64 Ionic Complex for Taste Masking: Preparation and Chemometric Evaluation

The objective of the present work was to evaluate and characterize a pediatric- friendly formulation of a bitter tasting drug, oseltamivir phosphate (drug). Amberlite IRP64 (resin) was used to make ionic complexes for masking its bitterness. Complexes of four drug-to-resin ratios, 1:1, 1:2, 1:4, and 1:6 (w/w), were prepared and characterized. At buccal pH of 6.8, drug–resin complexes of 1:1,1:2,1:4, and 1:6 ratios released 42.13%, 23.26%, 4.13%, and 14.94%, respectively, of loaded drug after 20 s. However, at stomach pH of 1.2 (0.1 N HCl), 61.96%, 70.18%, 85.88%, and 91.42% of drug was released from the same complexes in 6 min. Near-infrared (NIR) chemical imaging of the complexes showed homogeneous distribution of drug in the resin. Chemometric partial least squares model using NIR data of the drug showed a high correlation between calibration and predicted data(R² > 0.998). Overall, these results indicated the complex formation between drug and resin. The pH dependence of drug release from these complexes could minimize drug release in the mouth, whereas immediately releasing it in the stomach. Electronic tongue used to evaluate taste indicated that conductivity taste signals were different from control, suggesting taste masking of the drug.     

Taste masking analysis in pharmaceutical formulation development using an electronic tongue

The purpose of this study is to assess the feasibility for taste masking and comparison of taste intensity during formulation development using a multichannel taste sensor system (e-Tongue). Seven taste sensors used in the e-Tongue were cross-selective for five basic tastes while having different sensitivity or responsibility for different tastes. Each of the individual sensors concurrently contributes to the detection of most substances in a complicated sample through the different electronic output. Taste-masking efficiency was evaluated using quinine as a bitter model compound and a sweetener, acesulfame K, as a bitterness inhibitor. In a 0.2 mM quinine solution, the group distance obtained from e-Tongue analysis was reduced with increasing concentration of acesulfame K. This result suggests that the sensors could detect the inhibition of bitterness by a sweetener and could be used for optimization of the sweetener level in a liquid formulation. In addition, the bitterness inhibition of quinine by using other known taste-masking excipients including sodium acetate, NaCl, Prosweet^® flavor, and Debittering^® powder or soft drinks could be detected by the e-Tongue. These results further suggest that the e-Tongue should be useful in a taste-masking evaluation study on selecting appropriate taste-masking excipients for a solution formulation or a reconstitution vehicle for a drug-in-bottle formulation. In another study, the intensity of the taste for several drug substances known to be bitter was compared using the e-Tongue. It was found that the group distance was 695 for prednisolone and 686 for quinine, which is much higher than that of caffeine (102). These results indicate that the taste of prednisolone and quinine is stronger or more bitter than that of caffeine as expected. Based on the group distance, the relative intensity of bitterness for these compounds could be ranked in the following order: ranitidine HCl > prednisolone Na > quinine HClphenylthiourea > paracetamol  sucrose octaacetate > caffeine. In conclusion, the multichannel taste sensor or e-Tongue may be a useful tool to evaluate taste-masking efficiency for solution formulations and to compare bitterness intensity of formulations and drug substances during pharmaceutical product development.     

Hot Melt Extrudates Formulated Using Design Space: One Simple Process for Both Palatability and Dissolution Rate Improvement

This work aimed at obtaining an optimized itraconazole (ITZ) solid oral formulation in terms of palatability and dissolution rate by combining different polymers using hot melt extrusion (HME), according to a simplex centroid mixture design. For this, the polymers Plasdone^® (poly(1-vinylpyrrolidone-co-vinyl acetate) [PVP/VA]), Klucel^® ELF (2-hydroxypropyl ether cellulose [HPC]), and Soluplus^® (SOL, polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol) were processed using a laboratory HME equipment operating without recirculation at constant temperature. Samples were characterized by physicochemical assays, as well as dissolution rate and palatability using an e-tongue. All materials became homogeneous and dense after HME processing. Thermal and structural analyses demonstrated drug amorphization, whereas IR spectroscopy evidenced drug stability and drug-excipient interactions in HME systems. Extrudates presented a significant increase in dissolution rate compared to ITZ raw material, mainly with formulations containing PVP/VA and HPC. A pronounced improvement in taste masking was also identified for HME systems, especially in those containing higher amounts of SOL and HPC. Data showed polymers act synergistically favoring formulation functional properties. Predicted best formulation should contain ITZ 25.0%, SOL 33.2%, HPC 28.9%, and PVP/VA 12.9% (w/w). Optimized response considering dissolution rate and palatability reinforces the benefit of polymer combinations.     

Preparation and characterization of enrofloxacin/carbopol complex in aqueous solution

Since the bitter taste of enrofloxacin apparently limit the patient compliance in the oral formulations of the antibacterial agent, the masking of the taste is essential for the improvement of the therapeutic effectiveness. Therefore, this study was carried out to examine the feasibility of taste masking of enrofloxacin by the retardation of its dissolution rate using the formation of complex between the drug and Carbopol. The complexation between Carbopol and enrofloxacin was confirmed by turbidity, UV spectrophotometry, wide angle X-ray diffraction, and differential scanning calorimetry. The enrofloxacin content in the complexes was 34% (Carbo-enrofloxacin complex I) and 57% (Carbo-enrofloxacin complex II) depending on the preparation method. The dissolution rate of enrofloxacin from the complex increased as the pH was reduced. The dissolution rate of enrofloxacin from the Carbo-enrofloxacin complex I was significantly lower than that of the enrofloxacin powder. Therefore, these observations suggest that Carbo-enrofloxacin complex I can be used to mask the taste of enrofloxacin.     

Effect of chitosan crosslinking on bitterness of artemether using response surface methodology

This work examines the influence of various process parameters on artemether entrapped in crosslinked chitosan microparticles for masking bitterness. A central composite design was used to optimize the experimental conditions for bitterness masking. Critical parameters such as the amounts of artemether, chitosan and crosslinking agent have been studied to evaluate how they affect responses such as incorporation efficiency, particle size and drug release at pH 6.8. The desirability function approach has been used to find the best compromise between the experimental results. The optimized microparticles were characterized by Fourier transform infrared spectroscopy and differential scanning calorimetry. Bitterness score was evaluated by human gustatory sensation test. Multiple linear regression analysis revealed that the crosslinking of chitosan significantly affects incorporation efficiency, particle size and drug release at pH 6.8. The bitterness score of microparticles was decreased to 0, compared with 3+ for pure artemether. The proposed method completed masked the bitter taste of artemether.     

Specific interactions between diphenhydramine and alpha-helical poly(glutamic acid) - A new ion-pairing complex for taste masking and pH-controlled diphenhydramine release.

Formation of drug/excipient complex through ionic interactions has proven to be very effective for both controlled release and taste masking. Unfortunately, the ionic interactions between drugs and small molecule excipients are usually weak, and the stability of the formed complexes can be greatly influenced by solution ionic strength. In this study, we explored to formulate diphenhydramine (DPH), a very bitter tasting drug, using small molecular weight and carboxyl group containing polymers. Studies showed that DPH interacted with alpha-helical poly(glutamic acid) specifically to produce DPH/poly(glutamic acid) complexes, mostly spherical in shape with a diameter of around 1.0mum. Other drugs with similar chemical structures as DPH, such as phenylephrine and pseudoephedrine, could not form complexes with poly(glutamic acid) or other polymers under the same conditions. Although DPH in DPH/poly(glutamic acid) complexes existed amorphously, it showed increased stability.In vitro studies using electronic tongue demonstrated that poly(glutamic acid) might be as effective as sucralose for DPH bitter taste blocking. In addition, DPH/poly(glutamic acid) complexes were not stable in neutral or weak acidic (pH>5) environments and dissolved rapidly and completely. Therefore, DPH/poly(glutamic acid) complex may serve as a new formulation for taste masking and controlled DPH release in gastrointestinal tract. This is the first report that small molecule drugs can interact with peptides of specific secondary structures to form stable complexes. In addition to greatly expanded ion-pairing excipient pool, application of peptides in drug formulation may also solve the selectivity and stability problems faced by current small molecule excipients.     

Influence of chitosan crosslinking on bitterness of mefloquine hydrochloride microparticles using central composite design

The present work examines the influence of various process and product parameters on mefloquine hydrochloride (MFL) entrapped in crosslinked chitosan microparticles for masking the bitterness. A central composite design (CCD) was employed to investigate the effect of three process and product variables, namely amount of MFL, chitosan and sodium hydroxide (crosslinking agent) on the incorporation efficiency, particle size, drug release at pH 6.8 and bitterness score. The microparticles were prepared by ionotropic gelation method, with a hardening time of 60 min. The optimum condition for process and product variables was evaluated using desirability function. The model is further cross validated for bias. The optimized microparticles were characterized by Fourier transform infrared spectroscopy and differential scanning calorimetry. Bitterness score was evaluated by human gustatory sensation test. Multiple linear regression analysis revealed that the crosslinking of chitosan significantly affects incorporation efficiency, particle size, drug release and bitterness score. The bitterness score was decreased to zero compared to 3+ of pure MFL. It can be inferred that the proposed methodology can be used to prepare MFL microparticles for bitter taste masking.     

Evaluation of the bitterness of antibiotics using a taste sensor

The bitterness of nine commercial antibiotics (clarithromycin, erythromycin, cefdinil, doxycycline, vancomycin, tetracycline, minocycline, oxytetracycline and bacampicillin) was evaluated in human gustatory sensation tests with nine volunteers. The bitterness of 0.1-0.3 mM solutions (or suspensions in the case of clarithromycin) of the antibiotics was then measured using an artificial multichannel taste sensor. In the sensor measurements, three variables were used to predict estimated bitterness in single and multiple regression analysis and principal component analysis: sensor output as relative value (R), the change of membrane potential caused by adsorption (C) and C/R. Particularly good correlation was obtained between obtained bitterness scores and predicted scores using C from channel 2 of the sensor (r2=0.870, P<0.005) and C/R values for channels 2 and 3 (r2=0.947, P<0.005). The taste sensor was also successful in assessing the bitterness intensity of clarithromycin powder suspensions of various concentrations. Clarithromycin has a low aqueous solubility but is the most bitter of the nine antibiotics. Sensory data from channel 3 of the sensor predicted the bitterness of clarithromycin powder suspensions and their filtered solutions well. Finally, the bitterness intensity of a commercial clarithromycin dry syrup product (Clarith dry syrup, Taisho Pharmaceutical Co. Ltd, Tokyo, Japan) was evaluated in gustatory sensation tests and using the taste sensor. In Clarith dry syrup the drug is coated with aminoalkyl methacrylate polymer using a spray congealing method. The taste sensor results confirmed that the polymer was successful in almost completely masking the bitter taste of the dry syrup product.     

A Polymer Carrier System for Taste Masking of Macrolide Antibiotics

A polymer carrier system was developed to reduce the bitterness of erythromycin and its 6-O-methyl derivative, clarithromycin, by absorption to Carbopol. The mechanism involves ionic bonding of the amine macrolide to the high molecular weight polyacrylic acid, thereby removing the drug from the solution phase in an ion-free suspension. After ingestion, endogenous cations displace the drug from the polymer in the gastrointestinal tract to achieve bioavailability. The macrolide-Carbopol complexes were prepared by dissolving or slurrying predetermined ratios of drug and polymer in water or hydroalcoholic mixtures. A series of in vitro equilibrium studies, taste screening, and bioavailability studies in dogs established the characteristics for the various drug-polymer ratios. Taste protection was further improved by encapsulating the adsorbate particles with polymer coatings. Hydroxypropyl methylcellulose phthalate (HP-55) provided the best combination of suspension stability, taste protection and bioavailability. Human bioavailability studies demonstrated that the microencapsulated Carbopol absorbates of erythromycin and clarithromycin gave blood levels comparable to those obtained from conventional solid formulations.     

基于苦味产生机制的掩味策略与评价

口服制剂中许多药物尤其是中药常常会由于不良口味的影响,致使患者的顺应性降低,限制了临床应用。文章以苦味产生机制为主线,综述目前药物掩味技术的原理、特点和制备过程,并简述掩味技术评价方法的最新进展。     

Palatable reconstitutable dry suspension of artemether for flexible pediatric dosing using cyclodextrin inclusion complexation

The present research was conducted to investigate the inclusion complexation of artemether (ARM) with beta-cyclodextrin (CD) with the aim of masking the bitterness along with improving the drug release and preparing a stable palatable formulation of ARM especially for pediatrics. A physical mixture and kneaded system were prepared to study the inclusion complexation. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM) were performed to identify the physicochemical interaction between drug and carrier, hence its effect on drug release. Reconstitutable dry suspension was evaluated for angle of repose, sedimentation characterization and pH. In vitro drug release studies for physical mixture and kneaded system were performed at pH, 1.2 and 6.8. Bitterness score was evaluated using gustatory sensation test. The FTIR, DSC and XRPD studies indicated inclusion complexation in physical mixture and kneaded system. In addition, physical mixture and kneaded system exhibited improved drug release at pH, 1.2 and 6.8. To formulate palatable reconstitutable dry suspension of ARM, the 1:20M physical mixture was selected based on bitterness score. Reconstitutable dry suspension prepared using physical mixture (DS4), showed complete bitter taste masking, good flowability and ease of redispersibility. Taste evaluation of reconstitutable dry suspension in human volunteers rated tasteless with a score of 0 to DS4 and 3 to DS5 (reconstitutable dry suspension prepared using pure ARM). This conclusively demonstrated a stable and palatable reconstitutable dry suspension of ARM using CD inclusion complexation for flexible pediatric dosing.     

Palatable reconstitutable dry suspension of artemether for flexible pediatric dosing using cyclodextrin inclusion complexation

The present research was conducted to investigate the inclusion complexation of artemether (ARM) with beta-cyclodextrin (CD) with the aim of masking the bitterness along with improving the drug release and preparing a stable palatable formulation of ARM especially for pediatrics. A physical mixture and kneaded system were prepared to study the inclusion complexation. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM) were performed to identify the physicochemical interaction between drug and carrier, hence its effect on drug release. Reconstitutable dry suspension was evaluated for angle of repose, sedimentation characterization and pH. In vitro drug release studies for physical mixture and kneaded system were performed at pH, 1.2 and 6.8. Bitterness score was evaluated using gustatory sensation test. The FTIR, DSC and XRPD studies indicated inclusion complexation in physical mixture and kneaded system. In addition, physical mixture and kneaded system exhibited improved drug release at pH, 1.2 and 6.8. To formulate palatable reconstitutable dry suspension of ARM, the 1:20M physical mixture was selected based on bitterness score. Reconstitutable dry suspension prepared using physical mixture (DS4), showed complete bitter taste masking, good flowability and ease of redispersibility. Taste evaluation of reconstitutable dry suspension in human volunteers rated tasteless with a score of 0 to DS4 and 3 to DS5 (reconstitutable dry suspension prepared using pure ARM). This conclusively demonstrated a stable and palatable reconstitutable dry suspension of ARM using CD inclusion complexation for flexible pediatric dosing.     

Preparation of roxithromycin-polymeric microspheres by the emulsion solvent diffusion method for taste masking

Microspheres of roxithromycin with Eudragit S100 and silica were prepared by the emulsion solvent diffusion method to mask the bitter taste of the antibiotic. The effect of different polymers and drug-polymer ratios on the taste masking and the characteristics of the microspheres were investigated. It was found that Eudragit S100 was the best for masking the unpleasant taste of roxithromycin among the six kinds of polymers investigated. The results of DSC, X-ray diffraction and IR showed that there were several combinations of roxithromycin and Eudragit S100. The influence of other formulation factors, i.e. dichloromethane-acetone ratios and silica-polymer ratios on the properties of the microspheres were also examined. In conclusion, the results of the present study will be helpful for the preparation of oral forms of roxithromycin with an acceptable taste.     

Anhydrous Carbopol polymer gels for the topical delivery of oxygen/water sensitive compounds

PURPOSE: The purpose of this study was the development and evaluation of an anhydrous glycerin-based Carbopol gel in order to study the stability of the oxygen/water-sensitive agent epigallocatechin gallate (EGCG). METHODS: Various Carbopol polymers were investigated rheologically at concentrations of 0.25-1% using a Brookfield viscometer in order to evaluate their ability to form anhydrous glycerin-based formulations. The addition of Transcutol P was evaluated in order to create a gel that can be utilized for the incorporation of more lipophilic compounds. The suitability of standard neutralizers and their useful concentrations were determined to develop guidelines for formulation optimization. An accelerated stability study was performed at 50 degrees C to evaluate the degradation of EGCG in an anhydrous glycerin gel. RESULTS: It was found that Carbopol 974 is the most efficient thickener for anhydrous glycerin formulations. In contrast to aqueous gels, anhydrous gels are formed without the addition of neutralizers. The rank-order viscosity of the nonneutralized gels studied was 974 > 971 > 981 > Pemulen TR-2 approximately 980. The addition of neutralizers resulted in a further increase in gel viscosity, with a maximum being reached at a concentration of approximately 0.5% w/w. The incorporation of Transcutol P resulted in a concentration-dependent loss of gel viscosity. The stability data showed that no degradation of EGCG had occurred. CONCLUSION: It was shown that anhydrous glycerin-based Carbopol gels can be prepared without the need for neutralization. Such vehicles are promising for the incorporation of oxygen/water-sensitive drugs.     

壬苯醇醚阴道用缓释凝胶的研制

目的制备壬苯醇醚阴道用缓释凝胶并优化其处方与工艺。方法采用正交试验设计 ,考察了聚卡波菲用量、卡波沫用量、pH值、甘油用量、液体石蜡用量、山嵛酸甘油酯用量及不同工艺对释放度的影响 ,与国外产品进行残差平方和、拟合度、区分因子和相似因子比较 ,确定壬苯醇醚阴道用缓释凝胶的处方工艺 ,并考察了其初步稳定性。结果优化所得处方工艺为 :聚卡波菲用量0 5 % (w) ,卡波沫用量 1% (w) ,甘油用量为 5 % (w) ,液体石蜡用量为 5 % (w) ,山嵛酸甘油酯用量为 1% (w) ,pH值为 4 5 ,选用工艺 1。 结论按优化处方工艺制得的壬苯醇醚阴道用缓释凝胶稳定 ,与国外产品比较具有相似的释放度 ,且以复合模式释放。     

Nasal mucoadhesive delivery systems of the anti-parkinsonian drug, apomorphine: influence of drug-loading on in vitro and in vivo release in rabbits.

Lyophilized polyacrylic acid powder formulations loaded with apomorphine HCl were prepared and the influence of drug loading on in vitro release and in vivo absorption studied after intranasal administration in rabbits. These formulations prepared with Carbopol 971P, Carbopol 974P and polycarbophil sustained apomorphine release both in vitro and in vivo. The in vitro release rate and mechanism were both influenced by the drug loading. There was no large influence of drug loading on the time to achieve the peak (Tmax) for a particular polymer, but Tmax differed between different polymers. For a particular drug loading, the Tmax from Carbopol 971P was the slowest compared with that for Carbopol 974P and polycarbophil; however, only the Tmax from Carbopol 971P loaded with 15% w/w of apomorphine was significantly longer than polycarbophil of similar drug loading (P=0.0386). The trend further observed was that increasing drug loading led to increased peak plasma concentration and area under the curve (AUC). In the second part of this study, a mixture containing an immediate release component and sustained release formulation was administered in an attempt to increase the initial plasma level, as this could be therapeutically beneficial. Only one peak plasma concentration was observed and the initial plasma concentrations were no higher than those obtained with solely sustained release formulation. The Tmax, the peak plasma drug concentration (Cmax) and AUC from the lactose-containing formulation were lower than the formulation without lactose but the differences were only marginally statistically significant for Cmax (P=0.0911) and AUC (P=0.0668), but not Tmax (P=0.2788).     

Formulation and evaluation of new long acting metoprolol tartrate ophthalmic gels

The rationale of the present work is to formulate and evaluate metoprolol tartrate (MT), which is a beta-1 selective adrenergic blocking agent in a new ocular gel delivery system; this is our way and method to increase its contact to the cornea, giving a longer time of drug contact to the eye and slow possible release from the preparation. Metoprolol tartrate is chosen as a candidate for gel formulation because although it has been available for a few years as ophthalmic solutions, it has not been marketed as an ocular gel yet. Two polymers; Carbopol 934 and Pluronic F127 (PF127) were used in two different concentrations in this study. Metoprolol tartrate was used in two concentrations, 0.5% and 1% (w/w). All formulations were exposed to visual examinations, pH measurement, in vitro release, rheological study and differential scanning calorimetry (DSC). Results showed that all formulations were clear, showed pH within the acceptable range suitable to be administered in the eye, and exhibited pseudoplastic flow behavior. DSC results concluded that, MT was compatible with different polymers used. In vitro release results showed that the release rate of metoprolol tartrate from gel preparations decreased as an inverse function of polymer concentration, and the release rate of the drug increased as the initial concentration increased. Intra-ocular pressure (IOP) measurements of rabbit’s eye treated with 1% (w/w) metoprolol tartrate in gel formulations with different concentrations of the polymer were determined. Carbopol 934 gel formulations showed that this polymer extended the duration of pressure reducing effect of MT to more than 5hr when compared with Pluronic F127 gel formulations. The area above the curve (AAC), maximum response, time of maximum response (t_max), and the duration of the drug action were also calculated.     

Optimizing the taste-masked formulation of acetaminophen using sodium caseinate and lecithin by experimental design

In a previous study of ours, the association of sodium caseinate and lecithin was demonstrated to be promising for masking the bitterness of acetaminophen via drug encapsulation. The encapsulating mechanisms were suggested to be based on the segregation of multicomponent droplets occurring during spray-drying. The spray-dried particles delayed the drug release within the mouth during the early time upon administration and hence masked the bitterness. Indeed, taste-masking is achieved if, within the frame of 1–2 min, drug substance is either not released or the released amount is below the human threshold for identifying its bad taste. The aim of this work was (i) to evaluate the effect of various processing and formulation parameters on the taste-masking efficiency and (ii) to determine the optimal formulation for optimal taste-masking effect. Four investigated input variables included inlet temperature (X₁), spray flow (X₂), sodium caseinate amount (X₃) and lecithin amount (X₄). The percentage of drug release amount during the first 2 min was considered as the response variable (Y). A 2⁴-full factorial design was applied and allowed screening for the most influential variables i.e. sodium caseinate amount and lecithin amount. Optimizing these two variables was therefore conducted by a simplex approach. The SEM and DSC results of spray-dried powder prepared under optimal conditions showed that drug seemed to be well encapsulated. The drug release during the first 2 min significantly decreased, 7-fold less than the unmasked drug particles. Therefore, the optimal formulation that performed the best taste-masking effect was successfully achieved.     

Multiresponse optimization of the properties of albendazole-chitosan microparticles

The loading of albendazole into biodegradable polymeric microparticles provides an attractive alternative to improve the drug dissolution rate. Experimental design and optimization techniques were implemented for the development of albendazole-chitosan microparticles using the ionic interaction method. The effect of seven different factors (chitosan concentration, pH of chitosan solution, stirring rate, stirring time, temperature, ionic agent and pH of ionic solutions) were studied on six responses: the yield, pH, morphology, size, dissolution rate and encapsulation efficiency of the microparticles. During the screening phase, the factors were evaluated at three levels each, in order to identify those which exert a significant effect. Multiple response simultaneous optimization by using the desirability function was then used to find experimental conditions where the system shows the most adequate results. The optimal conditions were found to be: NaOH as ionic agent at a pH value of 13.0, chitosan concentration, 0.50% (w/v) at a pH value of 1.0 and stirring rate, 1,000 rpm.     

掩盖药物苦味技术的新进展

目的为掩盖药物苦味提供参考依据。方法将近年来国内外的有关文献分类、整理,归纳。结果和结论近年来涌现出许多掩盖药物苦味的新技术,如流化床技术、熔融制粒技术等;这些技术可有效掩盖药物的苦味,增加患者尤其是儿童和老年患者服药时的顺应性。