Development of Centrifugal Partition Chromatography for the Purification of Antibody-Drug Conjugates

Monoclonal antibody-drug conjugates (ADCs) are an expanding therapeutic class of biomolecules for which relatively few analytical and preparative separation options exist. Purification of ADCs with a specific drug antibody ratio is even more challenging. We report the first application of countercurrent separation (CCS) to this problem. An ADC mimic was successfully chromatographed using an aqueous two-phase system (ATPS) consisting of PEG 1000/sodium citrate pH 7.5/water, 17.75/17.75/64.50 (w/w/w). Notably, different partition coefficients (K) in this ATPS for the ADC mimic (0.09 < K < 0.16) and its monoclonal antibody backbone, IgG (0.16 < K < 0.27), were observed using CCS. Differential elution behavior of such high-molecular-weight biomolecules, 146,441 vs. ∼150,000 Da, using CCS has no precedent. The results provide a proof of concept for further exploration of the application of ATPSs and CCS to the separation of ADCs.

Stability Indicating Method for Polysorbate 80 in Protein Formulations

Polysorbates (also known as "Tween") are common components of protein formulations used to minimize protein adsorption and stabilize the protein. These nonionic surfactants are heterogenous mixtures of fatty acids with a complex reversed-phase profile due to the inhomogeneity of the polymers present. Polysorbates can be oxidized, which can be hard to detect in the complex polymer profile. Further adding to the analytical challenge is the lack of a chromophore for the detection of these polymers. The routine analysis of polysorbates in protein formulations was greatly improved through the introduction of online solid-phase extraction (SPE) to simplify the polysorbate profile for quantification. However, this method combines many of the polysorbate polymers into a single peak for detection, thus limiting its effectiveness for detecting degradation. To address the need for a stability indicating method without the complexity of the reversed-phase profile, an optimized online SPE method was developed and investigated. Using polysorbate 80, this investigation shows that further expanding the step gradient can yield a profile that is stability indicating and available for routine testing of protein formulation.

Diagnosis of Agglomeration and Crystallinity of Active Pharmaceutical Ingredients in Over the Counter Headache Medication by Electrospray Laser Desorption Ionization Mass Spectrometry Imaging

Agglomeration of active pharmaceutical ingredients (API) in tablets can lead to decreased bioavailability in some enabling formulations. In a previous study, we determined that crystalline APIs can be detected as agglomeration in tablets formulated with amorphous acetaminophen tablets. Multiple method advancements are presented to better resolve agglomeration caused by crystallinity in standard tablets. In this study, we also evaluate three “budget” over-the-counter headache medications (subsequently labeled as brands A, B, and C) for agglomeration of the three APIs in the formulation: Acetaminophen, aspirin, and caffeine. Electrospray laser desorption ionization mass spectrometry imaging (ELDI-MSI) was used to diagnose agglomeration in the tablets by creating molecular images and observing the spatial distributions of the APIs. Brand A had virtually no agglomeration or clustering of the active ingredients. Brand B had extensive clustering of aspirin and caffeine, but acetaminophen was observed in near equal abundance across the tablet. Brand C also had extensive clustering of aspirin and caffeine, and minor clustering of acetaminophen. These results show that agglomeration with active ingredients in over-the-counter tablets can be simultaneously detected using ELDI-MS imaging.

Exploiting Kinetic Solubility Differences for Low Level Detection of Crystallinity in Amorphous Drug Formulations

Background:

Enabling formulations have been implemented by the pharmaceutical industry as an effective tool for keeping Active Pharmaceutical Ingredient (API) in an amorphous state. Upon dosing in the amorphous state, many drugs which fail to demonstrate bioactivity due to the limited solubility and bioavailability of their crystalline form become bioavailable.

Purpose:

The analytical techniques use today for crystallinity detection are challenged by the sensitivity and robustness needed to achieve a 5% quantitation limit in low dose drug products. Our laboratory has developed a novel procedure capable of meeting this sensitivity and selectivity requirement. This is achieved by exploiting the differences in kinetic solubility of the formulated amorphous and free crystalline forms of API currently being used in dosage form platforms.

Methods:

Representative amorphous drug formulations were prepared and spiked with varying levels of crystalline drug substances to evaluate the selectivity and recovery of the crystalline drug substance from the product formulation. Kinetic solubility testing using a (i) Particle wetting phase, (ii) Particle suspending/erosion phase, (iii) Sampling time point and (iv) A total recovery determination for the drug substance.

Results:

The method selectively and quantitatively distinguishes crystalline drug substance from amorphous drug substance for samples spiked from 2.5% to 10% of the nominal label concentration of the API in the dosage form matrix.

Conclusion:

The kinetic solubility approach reported here achieves sensitive crystallinity quantitation for low drug level amorphous drug formulations at levels not yet achieved by complimentary analytical techniques.

Optimization and Automation of AOAC Official Method 971.47 for Determination of Roxarsone in Feed

AOAC Official Method 971.47 was optimized for use with solid-phase extraction (SPE) using the same activated carbon referenced in the original method. The optimization of AOAC 971.47 begins after the roxarsone is extracted into the 2% K2HPO4 solution of the original method; instead of 30 mL, 9 mL is pipetted into a test tube. Next, to flocculate the protein, 300 μL HCI is pipetted into the tube and mixed. After 15 min, the contents of the tube are filtered through a 0.45 μm nylon membrane filter equipped with a glass prefilter. Next, 7 mL clear filtrate is pipetted into a new test tube, followed by the addition of 234 μL NaOH, and the contents of the tube are mixed. The filtrate is then passed through a 400 mg bed of activated carbon packed in a 3 mL SPE tube at a flow rate of 1 mL/min. The spectrophotometric analysis of the eluate is not changed from the original AOAC 971.47. The optimized method was validated and semiautomated. Results of roxarsone determination by the optimized procedure were found to be acceptable at all levels of approved claims. For the commercial feed samples analyzed, recoveries by the automated method ranged from 93.7 to 104% of the results reported by an independent laboratory using AOAC 971.47.

Liquid Chromatographic Analysis of Bacitracin Methylene Disalicylate in Feed

Because of its peptide structure, bacitracin is not chemically distinct from many matrixes such as feeds or residue samples. Thus, bacitracin must be isolated from the matrix components or chemically altered to form a distinct component. Because of the complexity of this problem, bacitracin is still analyzed almost exclusively by microbiological methods. However, advances in solid-phase extraction has made sample isolation from the matrix much more practical. In this investigation both strong-cation exchange and C8 columns were used to isolate bacitracin for liquid chromatographic (LC) analysis. Results of both LC and microbiological analyses are compared.

Investigation of Assay Interference with Microbiological Determinations of Chlortetracycline in Feed Grade and Premix Samples

Studies were initiated to determine whether tetracycline components such as tetracycline and 4-epichlortetracycline present in commercial feed grade chlorteracycline (CTC) products interfere with AOAC Method 967.39. These investigations confirmed that the microbiological result for feed grade concentrates and premix products is not affected by the biomass matrix containing low levels of these other tetracycline components. Thus, the microbiological result can be directly correlated to the single CTC peak response in liquid chromatographic analytical procedures.

Gas Chromatographic Analysis of Fosfomycin in Plasma for Pharmacokinetic Analysis

An efficient method for gas chromatographic analysis of fosfomycin in plasma was developed for preliminary investigations of the bioavailability in poultry of 3 commercial complexes of fosfomycin: a levorotatory Ca(−) salt, a racemic Ca(±) salt, and a tromethamine (THAM) salt. The method was used to determine whether the less expensive racemic mixture would provide equivalent levels of fosfomycin in blood as the pure Ca(−) form and the THAM salt. The THAM salt, a more expensive product to market, was thought to have the greatest bioavailability. The assay is selective, sensitive, and applicable to pharmacokinetic analysis.

Rapid diagnosis of drug agglomeration and crystallinity in pharmaceutical preparations by electrospray laser desorption ionization mass spectrometry imaging

In this study we evaluate the applicability of electrospray laser desorption ionization mass spectrometry imaging (ELDI-MSI) to interrogate tablet formulations for the spatial distributions of ingredients. Tablet formulations with varying amounts of crystalline acetaminophen (the active pharmaceutical ingredient, API) were analyzed to determine if crystallinity could be evaluated via ELDI-MSI. ELDI-MSI concurrently imaged the (API, binders, and surfactants. The spatial distributions of amorphous API were very similar to that of the surfactants and different from that of crystalline API. The higher the crystallinity in the tablet formulation, the more agglomeration of the active ingredient was observed by ELDI-MSI. This study shows the capability of ELDI-MSI to diagnose agglomeration and crystallinity content in pharmaceutical preparations with little to no sample preparation. The ability to concurrently image APIs with other components provides valuable information as to their form in the tablet.

In silico Tools at Early Stage of Pharmaceutical Development: Data Needs and Software Capabilities

In early drug development, the selection of a formulation platform and decisions on formulation strategies have to be made within a short timeframe and often with minimal use of the active pharmaceutical ingredient (API). The current work evaluated the various physicochemical parameters required to improve the prediction accuracy of simulation software for immediate release tablets in early drug development. DDDPlus™ was used in simulating dissolution test profiles of immediate release tablets of ritonavir and all simulations were compared with experimental results. The minimum data requirements to make useful predictions were assessed using the ADMET predictor (part of DDDPlus) and Chemicalize (an online resource). A surfactant model was developed to estimate the solubility enhancement in media containing surfactant and the software's transfer model based on the USP two-tiered dissolution test was assessed. One measured data point was shown to be sufficient to make predictive simulations in DDDPlus. At pH 2.0, the software overestimated drug release while at pH 1.0 and 6.8, simulations were close to the measured values. A surfactant solubility model established with measured data gave good dissolution predictions. The transfer model uses a single-vessel model and was unable to predict the two in vivo environments separately. For weak bases like ritonavir, a minimum of three solubility data points is recommended for in silico predictions in buffered media. A surfactant solubility model is useful when predicting dissolution behavior in surfactant media and in silico predictions need measured solubility data to be predictive.

Simulated, biorelevant, clinically relevant or physiologically relevant dissolution media: The hidden role of bicarbonate buffer

In-vitro dissolution testing of pharmaceutical formulations has been used as a quality control test for many years. At early drug product development, in vivo predictive dissolution testing can be used for guidance in the rational selection of candidate formulations that best fit the desired in vivo dissolution characteristics. At present, the most widely applied dissolution media are phosphate-based buffers and, in some cases, the result of dissolution tests performed in such media have demonstrated reasonable/acceptable IVIVCs. However, the presence of phosphates in human GI luminal fluids is insignificant, which makes the use of such media poorly representative of the in vivo environment. The gastrointestinal lumen has long been shown to be buffered by bicarbonate. Hence, much interest in the development of suitable biorelevant in vitro dissolution media based on bicarbonate buffer systems has evolved. However, there are inherent difficulties associated with these buffers, such as maintaining the pH throughout the dissolution test, as CO₂ tends to leave the system. Various mathematical models have been proposed to analyze bicarbonate buffers and they are discussed in this review. Approaches such as using simpler buffer systems instead of bicarbonate have been proposed as surrogate buffers to produce an equivalent buffer effect on drug dissolution on a case-by-case basis. There are many drawbacks related to simpler buffers systems including their poor in vivo predictability. Considerable discrepancies between phosphate and bicarbonate buffer dissolution results have been reported for certain dosage forms, e.g. enteric coated formulations. The role and need of bicarbonate-based buffers in quality control testing requires scientific analysis. This review also encompasses on the use of bicarbonate-based buffers as a potentially in vivo predictive dissolution medium for enteric coated dosage forms.

Withdrawal of Life Support: How the Family Feels, and Why

The objectives of this study were to develop an instrument to assess the satisfaction of family members with withdrawal of life support (WLS), and to determine which factors are associated with greater levels of satisfaction. To do this, we developed a self-administered questionnaire that was sent to the next-of-kin of intensive care unit (ICU) patients dying following WLS. Over a six-month period, 69 patients died following WLS in the ICU. Three letters were returned “address unknown”, 33 did not respond, and 33 responded, of whom 29 agreed to participate (29/66 = 44% of those contacted). Of these, 24 (83%) strongly agreed with the patient's death being compassionate and dignified, one moderately agreed, one mildly agreed, one was neutral and two strongly disagreed. Items associated with greater satisfaction included: the process of WLS being well explained, WLS proceeding as expected, patient appearing comfortable, family/friends prepared for the decision, appropriate person initiating discussion, adequate privacy during WLS, chance to voice concerns. The study suggests factors that are important to consider in ensuring family comfort with the process of withdrawing life support.

Industry's View on Using Quality Control, Biorelevant, and Clinically Relevant Dissolution Tests for Pharmaceutical Development, Registration, and Commercialization

This article intends to summarize the current views of the IQ Consortium Dissolution Working Group, which comprises various industry companies, on the roles of dissolution testing throughout pharmaceutical product development, registration, commercialization, and beyond. Over the past 3 decades, dissolution testing has evolved from a routine and straightforward test as a component of end-product release into a comprehensive set of tools that the developer can deploy at various stages of the product life cycle. The definitions of commonly used dissolution approaches, how they relate to one another and how they may be applied in modern drug development, and life cycle management is described in this article. Specifically, this article discusses the purpose, advantages, and limitations of quality control, biorelevant, and clinically relevant dissolution methods.

Justification of disintegration testing beyond current FDA criteria using in vitro and in silico models

Drug product performance testing is an important part of quality-by-design approaches, but this process often lacks the underlying mechanistic understanding of the complex interactions between the disintegration and dissolution processes involved. Whereas a recent draft guideline by the US Food and Drug Administration (FDA) has allowed the replacement of dissolution testing with disintegration testing, the mentioned criteria are not globally accepted. This study provides scientific justification for using disintegration testing rather than dissolution testing as a quality control method for certain immediate release (IR) formulations. A mechanistic approach, which is beyond the current FDA criteria, is presented. Dissolution testing via United States Pharmacopeial Convention Apparatus II at various paddle speeds was performed for immediate and extended release formulations of metronidazole. Dissolution profile fitting via DDSolver and dissolution profile predictions via DDDPlus™ were performed. The results showed that Fickian diffusion and drug particle properties (DPP) were responsible for the dissolution of the IR tablets, and that formulation factors (eg, coning) impacted dissolution only at lower rotation speeds. Dissolution was completely formulation controlled if extended release tablets were tested and DPP were not important. To demonstrate that disintegration is the most important dosage form attribute when dissolution is DPP controlled, disintegration, intrinsic dissolution and dissolution testing were performed in conventional and disintegration impacting media (DIM). Tablet disintegration was affected by DIM and model fitting to the Korsmeyer-Peppas equation showed a growing effect of the formulation in DIM. DDDPlus was able to predict tablet dissolution and the intrinsic dissolution profiles in conventional media and DIM. The study showed that disintegration has to occur before DPP-dependent dissolution can happen. The study suggests that disintegration can be used as performance test of rapidly disintegrating tablets beyond the FDA criteria. The scientific criteria and justification is that dissolution has to be DPP dependent, originated from active pharmaceutical ingredient characteristics and formulations factors have to be negligible.

Expanding the analytical toolbox: pharmaceutical application of quantitative NMR

In response to the changing market pressures being applied to the pharmaceutical industry, a greater emphasis is being made to advance new drugs to market with minimal investment in early development stages. The use of quantitative NMR (q-NMR) has been shown to be a single point replacement for routine early development testing which previously combined elements of identity testing, chromatographic assay, moisture analysis, residual solvent analysis, and elemental analysis. This Feature will highlight the applications of q-NMR to early phase drug development testing and its efficient potency, solvent quantification, and relative response factor determinations.

Screening of Pirkle-type chiral stationary phases for HPLC enantioseparations

The majority of enantiomeric separations for purity analysis and quality control continue to be performed by normal-phase liquid chromatography and supercritical fluid chromatography. In this chapter, representative chromatographic screening procedures for the enantioseparations using Pirkle-type stationary phases are presented. As Pirkle-type phases are commonly applied to the preparative chromatographic isolation of enantiomers, volatile modifiers are used in this screen in order to be subsequently compatible with the techniques used to recover analytes from preparative scale isolations. The Stage 1 screen presented here is used initially for screening chiral entities. The gradients use cyclohexane and ethanol both with and without chromatographic modifiers. The Stage 2 screen is used for more challenging to resolve compounds that do not exhibit resolution using the Stage 1 screening procedure.

The solubility-permeability interplay when using cosolvents for solubilization: revising the way we use solubility-enabling formulations

We have recently reported the interplay between apparent aqueous solubility and intestinal membrane permeability, showing the trade-off between the two when using cyclodextrin- and surfactant-based systems as solubility-enabling formulations. In these cases, the decreased permeability could be attributed directly to decreased free fraction of drug due to the complexation/micellization inherent in these solubilization methods. The purpose of this study was to investigate the direct solubility-permeability interplay, using formulations in which complexation is not the mechanism for increased solubilization. The apparent aqueous solubility (S(aq)) and rat intestinal permeability (P(eff)) of the lipophilic drug progesterone were measured in systems containing various levels of the cosolvents propylene glycol and PEG-400, since this solubilization method does not involve decreased free fraction. Thermodynamic activity was maintained equivalent in all permeability studies (75% equilibrium solubility). Both cosolvents increased progesterone S(aq) in nonlinear fashion. Decreased P(eff) with increased S(aq) was observed, despite the constant thermodynamic activity, and the nonrelevance of free fraction. A mass-transport analysis was developed to describe this interplay. The model considers the effects of solubilization on the membrane permeability (P(m)) and the unstirred water layer (UWL) permeability (P(aq)), to predict the overall P(eff) dependence on S(aq). The analysis revealed that (1) the effective UWL thickness quickly decreases with ↑S(aq), such that P(aq) markedly increases with ↑S(aq); (2) the apparent membrane/aqueous partitioning decreases with ↑S(aq), thereby reducing the thermodynamic driving force for permeability such that ↓P(m) with ↑S(aq); (3) since ↑P(aq) and ↓P(m) with ↑S(aq), the UWL is shorted out and P(eff) becomes membrane control with ↑S(aq). The model enabled excellent quantitative prediction of P(eff) as a function of S(aq). This work demonstrates that a direct trade-off exists between the apparent solubility and permeability, which must be taken into account when developing solubility-enabling formulations to strike the optimal solubility-permeability balance, in order to maximize the overall oral absorption.

Analysis of PEG 400 in perfusate samples by aqueous normal phase (ANP) chromatography with evaporative light scattering detection

A rapid method for the analysis of polyethylene glycol (PEG 400) in perfusate samples is presented. Because PEG 400 lacks a strong chromophore in the UV range, detection was accomplished using evaporative light scattering detection (ELSD). In order to optimize the ELSD signal performance for a volatile mobile phase, the chromatographic separation was optimized using aqueous normal phase conditions on a Cogent® Diamond Hydride column.

Estimating the number of coronary artery bypass graft and percutaneous coronary intervention procedures in Canada: a comparison of cardiac registry and Canadian Institute for Health Information data sources

BACKGROUND

Provincial cardiac registries and the Canadian Institute for Health Information (CIHI) pan-Canadian administrative databases are invaluable tools for understanding Canadian cardiovascular health and health care. Both sources are used to enumerate cardiovascular procedures performed in Canada.

OBJECTIVE

To examine the level of agreement between provincial cardiac registry data and CIHI data regarding procedural counts for coronary artery bypass grafts (CABGs) and percutaneous coronary interventions (PCIs).

METHODS

CIHI staff obtained CABG and PCI counts from seven provinces that, in 2004, performed these procedures and had a cardiac registry (ie, British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Nova Scotia, and Newfoundland and Labrador). Structured mail questionnaires, and e-mail and telephone follow-ups elicited information from a designated registry respondent. The CIHI derived its counts of CABG and PCI procedures by applying the geographical boundaries, procedural definitions and analytical case criteria used by the cardiac registries to CIHI inpatient and day procedure databases. Steps were taken to reduce double-counting procedures when combining results from the two CIHI databases. Two measures were calculated: the absolute difference between registry and CIHI estimates, and the per cent agreement between estimates from the two sources.

RESULTS

All seven cardiac registries identified as eligible for the study participated. Agreement was high between the two sources for CABG (98.8%). For PCI, the level of agreement was high (97.9%) when CIHI sources were supplemented with day procedure data from Alberta.

CONCLUSIONS

The high level of agreement between cardiac registry and CIHI administrative data should increase confidence in estimates of CABG and PCI counts derived from these sources.

Validation of pharmaceutical potency determinations by quantitative nuclear magnetic resonance spectrometry

With the changing development paradigms in the pharmaceutical industry, laboratories are challenged to release materials for clinical studies with rapid turnaround times. To minimize cost demands, many businesses are looking to develop ways of using early Good Manufacturing Practice (GMP) materials of active pharmaceutical ingredients (API) for Good Laboratory Practice (GLP) toxicology studies. To make this happen, the analytical laboratory releases the material by one of three scenarios: (1) holding the GLP release until full GMP testing is ready, (2) issuing a separate lot number for a portion of the GMP material and releasing the material for GLP use, or (3) releasing the lot of material for GLP using alternate (equivalent) method(s) not specified for GMP release testing. Many companies are finding the third scenario to be advantageous in terms of cost and efficiency through the use of quantitative nuclear magnetic resonance (q-NMR). The use of q-NMR has proved to be a single-point replacement for routine early development testing that previously combined elements of identity testing, chromatographic assay, moisture analysis, residual solvent analysis, and elemental analysis. This study highlights that q-NMR can be validated to meet current regulatory analytical method guidelines for routine pharmaceutical analysis.

An evaluation of four commercial HPLC chiral detectors: A comparison of three polarimeters and a circular dichroism detector

With increasing frequency, new drug candidates being introduced into pharmaceutical drug pipelines are chiral. Often only one enantiomer exhibits the desired biological activity and the other enantiomer may exhibit undesired side effects, thereby making chiral purity an important parameter. The introduction of chiral analysis adds additional complications in drug development. The pharmaceutical industry is constantly striving to streamline processes and improve efficiencies in an effort to move molecules to market quickly. In order to simplify the process of chiral method development, chiral screening can be set up, however a successful chiral screen depends on optimizing two factors: the column and the detector. The following work investigated the second factor and evaluated two types of commercially available chiral detectors for their possible use in chiral method development and screening: polarimeters and circular dichroism (CD) detectors. Linearity, precision, and the limit of detection (LD) of six compounds (trans-stilbene oxide, ethyl chrysanthemate, propranolol, 1-methyl-2-tetralone, naproxen, methyl methionine) on four commercial detectors (three polarimeters and one CD detector) were determined experimentally and the limit of quantitation (LQ) calculated from the experimental LD. Trans-stilbene oxide worked well across all the detectors, showing good linearity, precision and low detection limits. However, the other five compounds proved to be more discriminating and showed that the circular dichroism detector performed better as a detector for chiral screens, over the polarimeters.

Effects of liquid chromatography mobile phases and buffer salts on phosphorus inductively coupled plasma atomic emission and mass spectrometries utilizing ultrasonic nebulization and membrane desolvation

Atomic spectrometry, specifically inductively coupled plasma atomic emission spectrometry (ICP-AES) and mass spectrometry (ICP-MS) show promise for heteroatom-based detection of pharmaceutical compounds. The combination of ultrasonic nebulization (USN) with membrane desolvation (MD) greatly enhances detection limits with these approaches. Because pharmaceutical analyses often incorporate liquid chromatography, the study herein was performed to examine the effects of solvent composition on the analytical behaviors of these approaches. The target analyte was phosphorus, introduced as phosphomycin. AES response was examined at the 253.7 nm atom line and mass 31 ions were monitored for the MS experiments. With pure aqueous solutions, detection limits of 5 ppb (0.5 ng in 0.1 mL injection volumes) were obtained with ICP-MS. The ICP-AES detection limit was 150 ppb. Solvent compositions were varied from 0 to 80% organic (acetonitrile and methanol) with nine buffers at concentrations typically used in liquid chromatography. In general, solvents and buffers had statistically significant, albeit small, effects on ICP-AES sensitivities. A few exceptions occurred in cases where typical liquid chromatography buffer concentrations produced higher mass loadings on the plasma. Indications are that isocratic separations can be reliably performed. Within reasonable accuracy tolerances, it appears that gradient chromatography can be performed without the need for signal response normalization. Organic solvent and buffer effects were more significant with ICP-MS. Sensitivities varied significantly with different buffers and organic solvent content. In these cases, gradient chromatography will require careful analytical calibration as solvent and buffer content is varied. However, for most buffer and solvent combinations, signal and detection limits are only moderately affected. Isocratic separations and detection are feasible.

Determination of active pharmaceutical ingredients by heteroatom selective detection using inductively coupled plasma mass spectrometry with ultrasonic nebuilization and membrane desolvation sample introduction

The combination of ultrasonic nebulization with membrane desolvation (USN-MD) is utilized to determine active pharmaceutical ingredients (API) by heteroatom inductively coupled mass spectroscopy (ICP-MS) detection. Ultrasonic nebulization provides efficient sampling while use of the membrane desolvator acts to reduce solvent-based interferences. This approach reduces interferences sufficiently so that a standard argon ICP-quadrupole MS can be utilized. Examined APIs and associated heteroatoms included: phosphomycin (P), amoxicillin (S), chlorpropamide (Cl), and ofloxacin (F). The optimum plasma r.f. powers for P, S, and Cl were in the 1000 to 1200 watts range. The high ionization energy of F required that the plasma be operated at 1500 W. The 16O2+ interference at mass 32 precluded determinations using the sulfur-32. The sulfur-34 (4.2% natural isotopic abundance), however, was relatively free of isobaric interferences. Interferences were relatively small at the mass 35 isotope of Cl, but increased with higher ICP r.f. powers. Overlaps were significant at the masses of monoisotopic species, fluorine-19 and phosphorus-31. Detection limits for P, S, Cl, and F of 2, 3, 90, and 3000 ng/mL, respectively, were generally lower than those produced with other quadrupole systems and comparable to or better than values published utilizing high-resolution instruments.

Plate Number Requirements for Establishing Method Suitability

Establishing the suitability of an analytical system has become a routine requirement in the testing of modern pharmaceuticals. Acceptable parameters that illustrate the system is performing as intended and in an equivalent manner to the original validation are often set at the time of method validation and transferred with the method to the production laboratory. For chromatographic methods, these parameters include--but are not limited to--resolution, tailing, and plate number specifications. Transferring methods is often a seamless transition from research to quality control. However, far too often the quality group receives arguably "overzealous" and strict requirements for the method. More specifically, chromatographic methods get issued with plate number specifications that far exceed the minimum number required to achieve sufficient resolution of the analytes. Presented here is a discussion of the setting of realistic plate number specifications that still maintain the minimum resolution of the chromatographic critical pair.

An Investigation into Detector Limitations Using Evaporative Light-Scattering Detectors For Pharmaceutical Applications

Evaporative light-scattering detection (ELSD) high-performance liquid chromatography (HPLC) is an alternative technology to low-wavelength UV analysis that is often employed when compounds lack sufficient absorptivity. Although ELSD provides an additional detector option for liquid chromatographers, studies in our laboratory indicate analyte properties may adversely affect the ability to detect certain molecules. In this investigation, a series of low-molecular-weight compounds of pharmaceutical interest are evaluated with two commercially available ELSDs. It is observed that melting point is a useful analyte property to consider in optimizing ELSD detectors. The melting point of the analyte should be significantly higher than what the compound will experience in the nebulizer/evaporator chambers to achieve the best analyte response. It is found that some analytes could not be distinguished from the evaporated mobile phase background when ELSD temperatures exceed the melting point of the compound. Though useful for many applications and of particular interest for compounds that are weak chromophores, ELSD falls short of being a "universal detector" technology. In addition to boiling points of mobile phase components, scientists should also consider the melting point and volatility of the analyte(s) when optimizing ELSD response.

Use of near-infrared spectrometry for quantitative determinations of selamectin and moisture in topical formulations

A rapid near-infrared spectrometric (NIR) method was qualified for use with the quantitative analysis of selamectin and moisture in topical formulations. Selamectin is currently marketed as a pet endectocide and is available in several formulations for cats and dogs. The use of NIR in this investigation replaces the in-process testing by liquid chromatography and concurrently provided moisture content that would otherwise only be available with additional Karl Fischer titration investigations. A seven-factor partial least square regression (PLS) of the second derivative spectra encompassing the wavelength region of 1450-2200 nm was used to quantify both selamectin and moisture content. A second three-factor PLS solely for water content was also applied and compared with the full model. This qualification confirms that this method may be used to quantitate selamectin and moisture as a process tool or to examine finished good samples. Each sample can be rapidly analyzed within 5 min on the current bench top system.

Liquid chromatographic determination of pyrantel tartrate in medicated formulations

The validation of a novel liquid chromatographic (LC) method for the determination of pyrantel tartrate in feed is presented. The method provides a significant improvement over the efficiency and precision of AOAC Official Method 978.30. The method was shown to be accurate, precise, linear, and robust for medicated articles. Unlike the official method, the LC method was shown to be a superior stability-indicating method. After the method was validated by using laboratory blends, the effectiveness of the method was demonstrated with marketed product as well.

Liquid Chromatographic Determination of Pyrantel Tartrate in Medicated Formulations

The validation of a novel liquid chromatographic (LC) method for the determination of pyrantel tartrate in feed is presented. The method provides a significant improvement over the efficiency and precision of AOAC Official Method 978.30. The method was shown to be accurate, precise, linear, and robust for medicated articles. Unlike the official method, the LC method was shown to be a superior stability-indicating method. After the method was validated by using laboratory blends, the effectiveness of the method was demonstrated with marketed product as well.

Rapid analysis of phentolamine by high-performance liquid chromatography

A rapid liquid chromatographic method is validated for the quantitative analysis of phentolamine. Phentolamine exists in three forms for this investigation: as a mesylate salt, hydrochloride salt, and free base. In solution, phentolamine dissociates from its salt and is chromatographed as free phentolamine. This validation confirms the analysis of each form, which is simply based upon molar mass differences encountered in weighing. As such, both the United States Pharmacopeia hydrochloride and mesylate standards are used throughout this validation to demonstrate this equivalency. The validation demonstrates that this method may be used to quantitate phentolamine, regardless of its salt form.

Column robustness case study for a liquid chromatographic method validated in compliance with ICH, VICH, and GMP guidelines

This article presents a case study in dealing with robustness investigations and attempts by our analytical laboratory to address these issues without sacrificing valuable time in revamping the method validation prior to submission. A liquid chromatographic method is developed for the analysis of a novel triazinetrione anticoccidial product. The method effectively separates the active pharmaceutical ingredient (API), impurities, and preservatives in the API and product formulation. For much of the validation, the method holds up to the rigorous guidelines of the International Conference of Harmonization, the International Cooperation on Harmonization of Technical Requirements for Registration of Veterinary Medicinal Products, and the Good Manufacturing Practices. However, in analyzing a base-degraded sample one of the impurity peaks yields inconsistent retention times (RTs) during a series of injections. When switching the system to another analytical column from the same supplier, this impurity peak elutes at a different retention window and the remaining peaks in the chromatographic profile remain essentially the same. This RT variation of a single peak in the chromatographic profile is observed with additional columns from the same supplier and from different manufacturing lots. This suitability problem is not encountered with the columns used in the method development stage. The method no longer meets the robustness criteria established for pharmaceutical methods. An investigation is commenced and it is discovered that with the addition of tetrabutylammonium hydroxide to the mobile phases, the impurity peak gives a consistent RT in relation to the active peak. The peak shows comparable RTs relative to that of the API peak with columns of different silica lots and bond lots. All peaks, including the aforementioned impurity peak, are well-resolved under the revised high-performance liquid chromatographic conditions. This temporary solution enables continued submission work for FDA, but the robustness of this method is still a concern. After further investigation, it is determined that inhomogeneity of the active sites on the column's stationary phase is the likely culprit. Fortunately, a new column is found to be more suitable for this method and a column qualification study is initiated.

Withdrawal of life support: how the family feels, and why

The objectives of this study were to develop an instrument to assess the satisfaction of family members with withdrawal of life support (WLS), and to determine which factors are associated with greater levels of satisfaction. To do this, we developed a self-administered questionnaire that was sent to the next-of-kin of intensive care unit (ICU) patients dying following WLS. Over a six-month period, 69 patients died following WLS in the ICU. Three letters were returned "address unknown", 33 did not respond, and 33 responded, of whom 29 agreed to participate (29/66 = 44% of those contacted). Of these, 24 (83%) strongly agreed with the patient's death being compassionate and dignified, one moderately agreed, one mildly agreed, one was neutral and two strongly disagreed. Items associated with greater satisfaction included: the process of WLS being well explained, WLS proceeding as expected, patient appearing comfortable, family/friends prepared for the decision, appropriate person initiating discussion, adequate privacy during WLS, chance to voice concerns. The study suggests factors that are important to consider in ensuring family comfort with the process of withdrawing life support.

Gas chromatographic analysis of fosfomycin in plasma for pharmacokinetic analysis

An efficient method for gas chromatographic analysis of fosfomycin in plasma was developed for preliminary investigations of the bioavailability in poultry of 3 commercial complexes of fosfomycin: a levorotatory Ca(-) salt, a racemic Ca(+/-) salt, and a tromethamine (THAM) salt. The method was used to determine whether the less expensive racemic mixture would provide equivalent levels of fosfomycin in blood as the pure Ca(-) form and the THAM salt. The THAM salt, a more expensive product to market, was thought to have the greatest bioavailability. The assay is selective, sensitive, and applicable to pharmacokinetic analysis.

Liquid chromatographic analysis of bacitracin methylene disalicylate in feed

Because of its peptide structure, bacitracin is not chemically distinct from many matrixes such as feeds or residue samples. Thus, bacitracin must be isolated from the matrix components or chemically altered to form a distinct component. Because of the complexity of this problem, bacitracin is still analyzed almost exclusively by microbiological methods. However, advances in solid-phase extraction has made sample isolation from the matrix much more practical. In this investigation both strong-cation exchange and C8 columns were used to isolate bacitracin for liquid chromatographic (LC) analysis. Results of both LC and microbiological analyses are compared.

The impact of musculoskeletal disorders in the population: are they just aches and pains? Findings from the 1990 Ontario Health Survey

OBJECTIVE

In light of the high frequency of symptoms of musculoskeletal (MSK) disorders in the population, our objective was to establish the impact of these disorders on morbidity and health care utilization.

METHODS

Analysis of interview data from the 1990 Ontario Health Survey (sample size 45,650 from the household population age > or = 16 years) has provided one of the first opportunities to relate reported MSK morbidity to disability, illness duration, and use of health services.

RESULTS

Overall, MSK disorders were reported as a cause of morbidity or health care utilization by 29% of the population aged > or = 16 years. The prevalence of chronic MSK disorders was 22%; this includes the 5% of the population who reported longterm disability due to MSK disorders. Of reported MSK disorders, 79% had a duration of over 6 months, and the median duration was 5 years. MSK disorders impact in the previous 2 weeks, defined as reduced activity or use of health care (seeing a health professional or taking prescription or nonprescription medication) specifically because of MSK disorders, was reported by 12% of the population, of whom 72% reported chronic MSK disorders. A health professional had been consulted within the previous year for 72% of the reported MSK disorders. The proportion with consultations was over 80% for durations of one year or less, and remained over 50% for disease durations > or = 10 years.

CONCLUSIONS

Reported MSK disorders cannot be dismissed as minor problems not requiring ongoing care in view of their long duration, disabling impact, and continuing consumption of health care services and resources.

Relative importance of musculoskeletal disorders as a cause of chronic health problems, disability, and health care utilization: findings from the 1990 Ontario Health Survey

OBJECTIVE

Musculoskeletal disorders (MSD) are a leading cause of morbidity in the population, yet their prominence seems to be insufficiently appreciated. We describe the ranking compared with other major body systems of the prevalence of MSD, including arthritis and rheumatism, and back/neck disorders, as a cause of chronic health problems, longterm disability, restricted activity days, consultation with health professionals, and use of both prescription and nonprescription drugs.

METHODS

We analyzed data from the 1990 Ontario Health Survey, a stratified random sample of the household dwelling population in Ontario, based on 45,650 individuals aged 16 years and over.

RESULTS

MSD ranked first in prevalence as the cause of chronic health problems, longterm disabilities, and consultations with a health professional and ranked 2nd for restricted activity days and use of both prescription and nonprescription drugs. No other body systems ranked invariably within the top 2 ranks for the morbidity indices examined. Even when compared to other major disease groups, arthritis and rheumatism ranked consistently in the top 3 and back/neck disorders also ranked high. MSD were mentioned as a reason for 40% of all chronic conditions, 54% of all longterm disability, 24% of restricted activity days and almost 20% of health care utilization. The impact of MSD was even greater in the 65 and over age group.

CONCLUSIONS

MSD have a major role in the health profile of the population. This high burden of illness should be considered in planning health care services and setting research priorities.

Use of Standard Additions to Diagnose Matrix Effects in the Atomic Absorption Spectrophotometric Analysis of Feed Blended for a Roxarsone Combination Study

Roxarsone (3-nitro-4-hydroxyphenylarsonic acid) is a feed additive commonly used in the poultry industry. Its use is approved at levels ranging from 0.0025 to 0.005% in feed. This additive is routinely assayed in industry by AOAC Official Methods 971.47 (Roxarsone In Feeds and Premixes: Spectrophotometric Method) and 986.39 (Roxarsone in Feeds: Atomic Absorption Spectrophotometric Method). The atomic absorption spectrophotometric method is quite advantageous, because it is accurate and efficient. Occasionally, analysis of feeds by this method yields questionable results. This communication details the investigation of such an occurrence and the application of standard additions to detect this problem in future analyses.

Uses of barium meal examination in dyspeptic patients under 50

No abnormality was found in 76 of 100 dyspeptic out-patients under the age of 50 who underwent barium meal examination, while various non-malignant lesions were found in the remaining 24. Only 10% of those under 30, and 10% of those with symptoms for less than a year proved to have any abnormality. Because of the radiographic results treatment was altered in only 11 patients, and most of these changes were small.

Progressive intrahepatic cholestasis of infancy and childhood. A clinicopathological study of patient surviving to the age of 18 years

A patient who developed chronic cholestatic jaundice during the 1st year of life and eventually died of liver cell failure at the age of 18 years is described. During the terminal illness Kayser-Fleischer-like rings were observed and the serum concentrations of total copper and ceruloplasmin were elevated. At autopsy, a mixed macronodular and micronodular cirrhosis was found and cholangiography and dissection of bile ducts revealed no obstructive lesion of the biliary tract. There was no family history of hepatobiliary disease. Liver biopsies obtained at the ages of 5 and 7 years showed accumulation of bile droplets in hepatocytes, normal-appearing bile ducts, no significant fibrosis, and intact lobular architecture. Striking features of the terminal cirrhosis were the presence of Mallory bodies and a marked excess of copper in the liver (2,175 mug per g dry weight). The latter two findings, as well as the elevated serum concentrations of total copper and ceruloplasmin, may be attributable to chronic cholestasis per se. This study emphasizes the clinical and therapeutic problems posed by chronic cholestasis of unknown etiology in childhood.

Pancytopenia after administration of distalgesic

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