A multidisciplinary approach to identify a degradation product in a pharmaceutical dosage form

An unknown degradation product found in non-MS compatible HPLC analysis was studied using a multidisciplinary approach. The unknown was separated and isolated from other components in the drug product by HPLC followed by ion trap MS to obtain MS(n) fragmentation patterns. Its chemical formula was determined using a high resolution time-of-flight mass spectrometer (TOF MS). Nuclear Magnetic Resonance (NMR) was used to elucidate the molecular structure. The impurity was identified as 5-hydroxymethyl furfural, which was a degradation product of lactose, one of the excipients used in the formulation of this dosage form.     

Development of electrochemical methods for determination of tramadol--analytical application to pharmaceutical dosage forms

A square-wave voltammetric (SWV) method and a flow injection analysis system with amperometric detection were developed for the determination of tramadol hydrochloride. The SWV method enables the determination of tramadol over the concentration range of 15-75 microM with a detection limit of 2.2 microM. Tramadol could be determined in concentrations between 9 and 50 microM at a sampling rate of 90 h(-1), with a detection limit of 1.7 microM using the flow injection system. The electrochemical methods developed were successfully applied to the determination of tramadol in pharmaceutical dosage forms, without any pre-treatment of the samples. Recovery trials were performed to assess the accuracy of the results; the values were between 97 and 102% for both methods.     

Orally disintegrating mini-tablets (ODMTs) - A novel solid oral dosage form for paediatric use

The new European regulations on paediatric medicines and recent WHO recommendations have induced an increased need for research into novel child-appropriate dosage forms. The aim of this study was the development of orally disintegrating mini-tablets (ODMTs) as a suitable dosage form for paediatric patients. The suitability of five commercially available ready-to-use tableting excipients, Ludiflash®, Parteck® ODT, Pearlitol® Flash, Pharmaburst® 500 and Prosolv® ODT, to be directly compressed into mini-tablets, with 2 mm in diameter, was examined. All of the excipients are based on co-processed mannitol. Drug-free ODMTs and ODMTs with a child-appropriate dose of hydrochlorothiazide were investigated.ODMTs could be produced with all investigated excipients. ODMTs with a sufficient crushing strength >7 N and a low friability <1% could be obtained, as well as ODMTs with a short simulated wetting test-time <5 s. ODMTs made of Ludiflash® showed the best results with crushing strengths from 7.8 N up to 11.8 N and excellent simulated wetting test-times from 3.1 s to 5.0 s. For each excipient, ODMTs with accordance to the pharmacopoeial specification content uniformity could be obtained. The promising results indicate that orally disintegrating mini-tablets may serve as a novel platform technology for paediatrics in future.     

Developability assessment in pharmaceutical industry: An integrated group approach for selecting developable candidates

This article describes the role and responsibilities of the Developability Assessment Group (DAG), a pharmaceutical Research and Development (R&D) subgroup, which supports drug discovery and development scientists with screening, developability assessment, and selection of new molecular entities (NMEs) for clinical studies. A strong collaboration between discovery group and DAG is essential for selecting the right NMEs for late-stage development, and consequently decreasing the NME attrition rate in late-stage development as well as in bringing down the associated cost and timelines. The investigations performed by DAG for evaluating research leads as well as the significance of these investigations in the developability assessment, the value of cutting edge tools and technologies, and the usefulness of the data in the decision making process are discussed in this review. Developability assessment of NMEs often includes physicochemical and biopharmaceutical characterization, development of suitable formulations for pharmacokinetic (PK), efficacy, and toxicity studies, selection of suitable physical form (salt, polymorph, etc.), and formulation development for phase I clinical studies. Overall DAG activities not only contribute to streamlining efficacy-toxicology evaluation, but also in building developability screens, which allow pharmacologically effective, minimally toxic, and developable candidates to reach the clinic and eventually to the market.     

A validated stability-indicating UPLC method for desloratadine and its impurities in pharmaceutical dosage forms

A novel stability-indicating gradient reverse phase ultra-performance liquid chromatographic (RP-UPLC) method was developed for the determination of purity of desloratadine in presence of its impurities and forced degradation products. The method was developed using Waters Aquity BEH C18 column with mobile phase containing a gradient mixture of solvents A and B. The eluted compounds were monitored at 280 nm. The run time was 8 min within which desloratadine and its five impurities were well separated. Desloratadine was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Desloratadine was found to degrade significantly in oxidative and thermal stress conditions and stable in acid, base, hydrolytic and photolytic degradation conditions. The degradation products were well resolved from main peak and its impurities, thus proved the stability-indicating power of the method. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. This method was also suitable for the assay determination of desloratadine in pharmaceutical dosage forms.     

A sustained release dosage form of acyclovir for buccal application: An experimental study in dogs

Acyclovir is an antiviral agent and it has been particularly used for the treatment of herpes simplex infections. The treatment of infection in the oral cavity is often difficult, because of insufficient drug concentration in saliva when acyclovir is administered via the oral route in conventional tablet form for systemic uptake. Therefore, it was aimed to prepare a tablet for buccal administration and to investigate its effectiveness by performing in vitro and in vivo experiments.

The solubility (1.559–4.584) and octanol/water partition coefficients ( ? 2.176 to ? 1.625) of the acyclovir were investigated at different pH conditions. A series of tablet formulations were prepared for buccal application and their dissolution properties were determined in artificial saliva medium. The effect of tablet ingredients on the release rate and mucoadhesion force was investigated. The dissolution properties of commercially available acyclovir tablets were also determined in the artificial gastric juice.

Franz type diffusion cells were used to determine acyclovir penetration through buccal mucosa from prepared buccal tablets.

Selected buccal tablets, commercial tablets and intravenous acyclovir solutions were administered to mongrel dogs and drug levels in the blood determined by HPLC.

A pharmacokinetic model for buccal application was also developed and blood concentrations were calculated theoretically and compared with the experimental results. Prepared buccal tablets were found to be effective for the treatment of viral infections locally within the oral cavity and also for systemic treatment.     

Validation and application of Vierordt's spectrophotometric method for simultaneous estimation of tamoxifen/coenzyme Q10 in their binary mixture and pharmaceutical dosage forms

For the sake of improving patient compliance and sustainability of chemotherapy healthcare system, both TC and CoQ10 were formulated as solid lipid nanoparticles (SLNs). The study was focused on establishing and validating a simple and reproducible spectrophotometric method for simultaneous determination of TC and CoQ10 in their binary mixture or pharmaceutical dosage forms. A new method based on simultaneous estimation of drug mixture without prior separation was developed. Validation parameters were checked with International Conference on Harmonization (ICH) guidelines. The accuracy and reproducibility of proposed method was statistically compared to HPLC. The TC and CoQ10 were quantified at absorptivity wavelengths of 236 nm and 275 nm, respectively. Calibration curves obeyed Beer's law in range of 2–14 µg/ml with a correlation coefficient (R²) of 0.999 in both methanol and simplified simulated intestinal fluid (SSIF). The %means recovery of TC and CoQ10 in pure state or binary mixture at various concentration levels were all around 100%. The low values of SD and %RSD (<2%) confirm high precision and accuracy of the proposed method. Formulated SLNs showed different %means recovery in range 81–92% for TC and 32–59% for CoQ10. The data obtained by applying simultaneous Vierordt's equations showed no statistical significance in comparison to HPLC. Vierordt's method was successfully applied as a simple, accurate, precise, and economical analysis method for estimating TC and CoQ10 concentrations in pure state, binary mixture and pharmaceutical dosage forms.     

Modification of physicochemical characteristics of active pharmaceutical ingredients and application of supersaturatable dosage forms for improving bioavailability of poorly absorbed drugs

New chemical entities are required to possess physicochemical characteristics that result in acceptable oral absorption. However, many promising candidates need physicochemical modification or application of special formulation technology. This review discusses strategies for overcoming physicochemical problems during the development at the preformulation and formulation stages with emphasis on overcoming the most typical problem, low solubility. Solubility of active pharmaceutical ingredients can be improved by employing metastable states, salt forms, or cocrystals. Since the usefulness of salt forms is well recognized, it is the normal strategy to select the most suitable salt form through extensive screening in the current developmental study. Promising formulation technologies used to overcome the low solubility problem include liquid-filled capsules, self-emulsifying formulations, solid dispersions, and nanosuspensions. Current knowledge for each formulation is discussed from both theoretical and practical viewpoints, and their advantages and disadvantages are presented.     

A multi-mechanistic drug release approach in a bead dosage form and in vitro/in vivo correlations

An in vitro/in vivo relationship of a combined multi-mechanistic dosage form has now been established in the literature. In our previous study, we successfully prepared a combination of immediate release, enteric coated, and controlled-release (CR) beads and mathematically modeled in vitro and in vivo drug release characteristics of the combination based on the release profiles of individual beads. The objective of the present study is to develop in vitro/in vivo correlations (IVIVC) for three individual beads and the combination using theophylline as a model drug and the beagle dog as an animal model. In the study, an IVIVC correlation is estimated by two-stage procedures: deconvolution followed by comparison of the fraction of drug absorbed to the fraction of drug dissolved. The Wagner-Nelson mass balance method was used to deconvolute plasma drug concentration-time curves. In vitro, a two-stage medium (0.1 N HCl and pH 6.5 phosphate buffer) was used for the dissolution test; a 2h first stage (acidic) was selected based on the average gastric emptying time in a fasted dog. In vivo, t(lag) was used for the gastric emptying process for enteric coated beads and the combination, which contains enteric coated beads. A time-scaling technique was used to consider the rate difference between in vitro dissolution and in vivo absorption in the process of IVIVC. As shown in the results, a point-to-point correlation was established for each formulation. The linear regression analysis of the correlation was r2>0.99 for all three individual beads and 0.97 for the combined bead dosage form. The results suggest level A IVIVCs indicating an appropriateness for the in vitro and in vivo models used in this study.     

A biorelevant in vitro release/permeation system for oral transmucosal dosage forms

This research describes the development and validation of a biorelevant in vitro release/permeation system to predict the in vivo performance of oral transmucosal dosage forms. The system is a biorelevant bidirectional transmucosal apparatus which allows better simulation of oral cavity physiological variables in comparison to compendial dissolution apparatuses and therefore may be a better predictor of in vivo behavior. The feasibility of the bidirectional apparatus was studied using smokeless tobacco (snus) as a model oral transmucosal product. In this research, nicotine release and permeation was investigated from commercially available snus using a modified USP IV flow-through apparatus, a commercially available vertical diffusion cell and a fabricated novel bidirectional transmucosal apparatus. The percent nicotine released/permeated was utilized as an input function for the prediction of in vivo plasma nicotine profiles by back calculation based on the Wagner-Nelson method. The prediction errors in C(max) and AUC(0-∞) with the USP IV flow-through device, vertical diffusion cell and novel apparatus were 4.03, 22.85 and 1.59 and -5.85, 5.85 and -9.27% respectively. This work demonstrated the suitability of the novel bidirectional transmucosal apparatus for predicting the in vivo behavior of oral transmucosal products.     

A validated LC method for the quantitative determination of celecoxib in pharmaceutical dosage forms and purity evaluation in bulk drugs

A new reversed-phase, isocratic LC method was developed for the quantitative determination of COX-2 inhibitor celecoxib in bulk drugs and in pharmaceutical dosages. The proposed method is also applicable for the purity evaluation of celecoxib in bulk drugs. 5-Methyl 2-Nitro phenol has been used as internal standard for the quantitative determination of celecoxib. The method has been completely validated and proven to be rugged. The limit of detection (LOD) and limit of quantitation (LOQ) for celecoxib impurities namely, 4-hydrazino benzene sulfonamide (Intermediate I) and 1-(4-methyl phenyl)-4,4,4-trifluro butan-1,3-dione (Intermediate II) were found to be 32.0 and 97 ng, respectively. The active pharmaceutical ingredient was extracted from its finished dosage form (capsule) using methanol. The percentage recoveries ranged from 90.7 to 93.8. The stability studies were performed for celecoxib solution placed on laboratory bench and in refrigerator for hundred days. The samples were found to be stable for the study period.     

A validated stability-indicating normal phase LC method for clopidogrel bisulfate and its impurities in bulk drug and pharmaceutical dosage form

A novel stability-indicating normal phase liquid chromatographic (NP-LC) method was developed for the determination of purity of clopidogrel drug substance and drug products in bulk samples and pharmaceutical dosage forms in the presence of its impurities and degradation products. This method is capable of separating all the related substances of clopidogrel along with the chiral impurities. This method can be also be used for the estimation of assay of clopidogrel in drug substance as well as in drug product. The method was developed using Chiralcel OJ-H (250 mm × 4.6 mm, 5 μm) column. n-Hexane, ethanol and diethyl amine in 95:5:0.05 (v/v/v) ratio was used as a mobile phase. The eluted compounds were monitored at 240 nm. Clopidogrel bisulfate was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. The degradation products were well resolved from main peak and its impurities, proving the stability-indicating power of the method. The developed method was validated as per International Conference on Harmonization (ICH) guidelines with respect to specificity, limit of detection, limit of quantification, precision, linearity, accuracy, robustness and system suitability.     

A sustained release dosage form of acyclovir for buccal application: an experimental study in dogs

Acyclovir is an antiviral agent and it has been particularly used for the treatment of herpes simplex infections. The treatment of infection in the oral cavity is often difficult, because of insufficient drug concentration in saliva when acyclovir is administered via the oral route in conventional tablet form for systemic uptake. Therefore, it was aimed to prepare a tablet for buccal administration and to investigate its effectiveness by performing in vitro and in vivo experiments.The solubility (1.559-4.584) and octanol/water partition coefficients ( - 2.176 to - 1.625) of the acyclovir were investigated at different pH conditions. A series of tablet formulations were prepared for buccal application and their dissolution properties were determined in artificial saliva medium. The effect of tablet ingredients on the release rate and mucoadhesion force was investigated. The dissolution properties of commercially available acyclovir tablets were also determined in the artificial gastric juice.Franz type diffusion cells were used to determine acyclovir penetration through buccal mucosa from prepared buccal tablets.Selected buccal tablets, commercial tablets and intravenous acyclovir solutions were administered to mongrel dogs and drug levels in the blood determined by HPLC.A pharmacokinetic model for buccal application was also developed and blood concentrations were calculated theoretically and compared with the experimental results. Prepared buccal tablets were found to be effective for the treatment of viral infections locally within the oral cavity and also for systemic treatment.     

Pyrocatechol violet in pharmaceutical analysis. Part I. A spectrophotometric method for the determination of some beta-lactam antibiotics in pure and in pharmaceutical dosage forms.

A fairly sensitive, simple and rapid spectrophotometric method for the determination of some beta-lactam antibiotics, namely ampicillin (Amp), amoxycillin (Amox), 6-aminopenicillanic acid (6APA), cloxacillin (Clox), dicloxacillin (Diclox) and flucloxacillin sodium (Fluclox) in bulk samples and in pharmaceutical dosage forms is described. The proposed method involves the use of pyrocatechol violet as a chromogenic reagent. These drugs produce a reddish brown coloured ion pair with absorption maximum at 604, 641, 645, 604, 649 and 641 nm for Amp, Amox, 6APA, Clox, Diclox and Flucolx, respectively. The colours produced obey Beer's law and are suitable for the quantitative determination of the named compounds. The optimization of different experimental conditions is described. The molar ratio of the ion pairs was established and a proposal for the reaction pathway is given. The procedure described was applied successfully to determine the examined drugs in dosage forms and the results obtained were comparable to those obtained with the official methods.     

A reversed‐phase high‐performance liquid chromatography method for bovine serum albumin assay in pharmaceutical dosage forms and protein/antigen delivery systems

Bovine serum albumin (BSA) is among the most widely used proteins in protein formulations as well as in the development of novel delivery systems as a typical model for therapeutic/diagnostic proteins and the new versions of vaccines. The development of reliable and easily available assay methods for quantitation of this protein would therefore play a crucial role in these types of studies. A simple gradient reversed‐phase high‐performance liquid chromatography with ultra‐violet detection (HPLC‐UV) method has been developed for quantitation of BSA in dosage forms and protein delivery systems. The method produced linear responses throughout the wide BSA concentration range of 1 to 100 µ g/mL. The average within‐run and between‐run variations of the method within the linear concentration range of BSA were 2.46% and 2.20%, respectively, with accuracies of 104.49% and 104.58% for within‐run and between‐run samples, respectively. The limits of detection (LOD) and quantitation (LOQ) of the method were 0.5 and 1 µg/mL, respectively. The method showed acceptable system suitability indices, which enabled us to use it successfully during our particulate vaccine delivery research project. Copyright © 2009 John Wiley & Sons, Ltd.     

A validated method for the determination and purity evaluation of benazepril hydrochloride in bulk and in pharmaceutical dosage forms by liquid chromatography

A gradient liquid chromatographic (LC) method has been developed for the determination and purity evaluation of benazepril hydrochloride in bulk and pharmaceutical dosage forms. The method is simple, rapid and selective. 5-Methyl-2-nitro phenol has been used as internal standard. The method is linear in the range of 50-800 microg. The precision for inter and intra-day assay variation of benazepril hydrochloride is below 1.6% RSD. The accuracy determined as relative mean error (RME) for the intra-day assay is within +/- 2.0%. The method is stability indicating, and is useful in the quality control of bulk manufacturing and also in pharmaceutical formulations.     

Development of a standardized analysis strategy for basic drugs, using ion-pair extraction and high-performance liquid chromatography - III. Analysis of pharmaceutical dosage forms

The usefulness of the standardized analysis strategy previously described for the determination of basic drugs in pharmaceutical dosage forms is evaluated. Several examples which typify experience in applying the strategy are reported. Ion-pair extraction techniques are compared with each other and with a classical extraction method in terms of their efficiency. The extraction technique with di(2-ethylhexyl)-phosphoric acid (HDEHP) is found to be the method of choice. The use of an internal standard is recommended. The selection of a suitable compound is greatly facilitated by referring to the chromatographic properties. It is shown that it is not necessary for the analyte and internal standard to be structurally similar. The combination of the HDEHP extraction technique with the preferred HPLC systems has been shown to be very useful in the routine analysis of pharmaceutical dosage forms.     

Development and validation of an assay for citric acid/citrate and phosphate in pharmaceutical dosage forms using ion chromatography with suppressed conductivity detection

The paper describes the development and validation of a simple, rapid, accurate, and sensitive ion chromatographic procedure to assay total citrate (citric acid/citrate) and phosphate in nine dosage forms. The dosage forms chosen represent all dosage forms in USP27-NF22 for which the respective monographs require an assay for either citric acid/citrate or citric acid/citrate and phosphate. Citrate and phosphate were separated in <10min by a hydroxide-selective column using anion-exchange chromatography with a 20mM potassium hydroxide eluent and detected by suppressed conductivity. The method showed linear responses over the concentration ranges 0.2-100microg ml(-1) (r(2) > 0.9990) for citrate and 0.2-60microg ml(-1) (r(2) = 0.9999) for phosphate, with limits of quantitation (signal-to-noise (S/N) = 10) of 0.2microg ml(-1) for both analytes. The accuracy of the procedure, determined by spiked recovery measurements, was within 95-105%. The intraday and the interday precision were demonstrated by the relative standard deviations (R.S.D.) of <1 and <2%, respectively, for both analytes. The ruggedness was determined by a full factorial design using analyst, equipment, column lot, and eluent preparation procedure as variables. The results show an overall R.S.D. of <3% and that an electrolytically generated 20mM KOH eluent produces assay results equivalent to a manually prepared 20mM NaOH eluent.