Ruben Lozano

Determination of inorganic pharmaceutical counterions using hydrophilic interaction chromatography coupled with a Corona CAD detector.

A simple generic approach was investigated for the determination of inorganic pharmaceutical counterions in drug substances using conventional high performance liquid chromatographic (HPLC) instruments. An intuitive approach combined Corona charged aerosol detection (CAD) with a polymer-based zwitterionic stationary phase in the hydrophilic interaction chromatography (HILIC) mode. Two generic methods based on this HILIC/CAD technique were developed to quantitate counterions such as Cl-, Br-, SO(4)(2-), K+, Ca2+ and Mg2+ in different pharmaceutical compounds. The development and capability of this HILIC/CAD technique analysis were examined. HILIC/CAD was compared to ion chromatography (IC), the most commonly used methodology for pharmaceutical counterion analysis. HILIC/CAD was found to have significant advantages in terms of: (1) being able to quantitate both anions and cations simultaneously without a need to change column/eluent or detection mode; (2) imposing much less restriction on the allowable organic percentage of the eluents than IC, and therefore being more appropriate for analysis of counterions of poorly water-soluble drugs; (3) requiring minimal training of the operating analysts. The precision and accuracy of counterion analysis using HILIC/CAD was not compromised. A typical precision of <2.0% was observed for all tested inorganic counterions; the determinations were within 2.0% relative to the theoretical counterion amount in the drug substance. Additionally, better accuracy was shown for Cl- in several drug substances as compared to IC. The main drawback of HILIC/CAD is its unsuitability for many of the current silica-based HILIC columns, because slight dissolution of silica leads to high baseline noise in the CAD detector. As a result of the universal detection characteristics of Corona CAD and the unique separation capabilities of a zwitterionic stationary phase, an intuitive and robust HPLC method was developed for the generic determination of various counterions in different drug substances. HILIC/CAD technique is a useful alternative methodology, particularly for determination of counterions in low-solubility drugs.

Influence of Formaldehyde Impurity in Polysorbate 80 and PEG‐300 on the Stability of a Parenteral Formulation of BMS‐204352: Identification and Control of the Degradation Product

The purpose of this study was to identify a degradation product formed in the clinical parenteral formulation of BMS‐204352, investigate the role of excipients in its formation, and develop a strategy to minimize/control its formation. The degradant was identified as the hydroxy methyl derivative (formaldehyde adduct, BMS‐215842) of the drug substance based upon liquid chromatography/mass spectroscopy (LC/MS), liquid chromatography/mass spectroscopy/mass spectroscopy (LC/MS/MS), nuclear magnetic resonance (NMR), and chromatographic comparison to an authentic sample of hydroxymethyl degradation product, BMS‐215842. An assay method for the detection of formaldehyde based on HPLC quantitation of formaldehyde dinitrophenylhydrazone was developed to quantitate its levels in various Polysorbate 80 and PEG 300 excipient lots. A direct relationship between the levels of formaldehyde in the excipients and the formation of the hydroxymethyl degradant was found. To confirm the hypothesis that the formaldehyde impurity in these two excipients contributed to the formation of the hydroxymethyl degradant, several clinical formulation lots were spiked with formaldehyde equivalent to 1, 10, and 100 mg/g of BMS‐204352. A correlation was found between the formaldehyde level and the quantity of the hydroxymethyl degradant formed upon storage at 5 and 25°C. From these experiments, a limit test on the formaldehyde content in polysorbate 80 and PEG 300 can be set as part of a strategy to limit the formation of the degradation product.

In-Situ Dissolution Testing Using Different UV Fiber Optic Probes and Instruments

Introduction: Fiber optic technology for dissolution testing has been a topic of interest for many researchers for some years. Josefson, Johansson, and Tortensson 1 published early research in this field in 1988. They explored the feasibility of using UV fiber optics for in-situ dissolution and to overcome sample turbidity interference without filtration. In 1993, Brown and Lin 2 used a single optical fiber and a photo diode array (PDA) UV/vis spectrometer to track dissolution in a single vessel. Their work was extended thereafter to use six optical fibers and a PDA spectrometer for multiple dissolution vessels 3. In 1995, Cho and coworkers developed a sevenchannel fiber optic dissolution system using a spectrometer with two-dimensional chargecoupled devices (CCD), which allowed the simultaneous monitoring of six dissolution vessels and a seventh reference vessel 4,5. Several other studies around the same time further explored the possibility of using fiber optic technology for special dissolution applications. For example, Chen and his group 6,7 employed a fiber optic based chemical sensor for continuous monitoring of in-situ dissolution. Gemperline et al 8 applied a CCD/fiber optic system for determining two-component dissolution profiles of a pharmaceutical product, which used a full-range spectral principal component regression methodology. Aldridge and coworkers 9 automated a single-probe fiber optic system that used a robot arm to move the probe from vessel to vessel for sequential testing. All these breakthrough studies had great impact on subsequent development of commercial instruments and established the platform for modern in-situ fiber optic dissolution testing. Commercial UV fiber optic dissolution instruments became available in 1999. Several manufacturers in the United States introduced their independently developed instruments one after another. These commercial instruments employed either a spectrometer with multi-channel CCDs 10, 11, multiple PDA spectrometers 12,13, or a scanning spectrometer with a mechanical multiplexer 14,15. Commercialization of this technology and its consequent availability to a broad range of users has attracted much attention from the pharmaceutical industry. Recent publications and research works further described the capability of this technology 16-18 and demonstrated that UV fiber optics is a breakthrough for dissolution testing. A regulatory perspective on this technology has also been discussed in a recent article 19.

Quantitative analysis of fosinopril sodium by capillary zone electrophoresis and liquid chromatography

A capillary zone electrophoresis (CZE) method was developed for the quantitative analysis of fosinopril sodium. Validation parameters of the CZE method were evaluated and compared to an existing LC method. In terms of precision and sensitivity. LC performance was superior to that of the CZE method for this application. The CZE method achieved better selectivity for several degradants of interest within a much shorter analysis time than did the LC method. Effects of detection wavelength, applied voltage and buffer concentration on optimization of the CZE method are presented. Effects of diluent composition on capillary loading and peak behaviour are also discussed.

Analytical Method Quality by Design for an On-Line Near-Infrared Method to Monitor Blend Potency and Uniformity

In this work, an example of analytical method quality by design (AQbD) principles applied to an in-line NIR method to monitor blend potency and uniformity in the manufacturing of an oral solid dosage product is presented. An integrated process analytical technology (PAT) method was developed following the AQbD workflow, including risk assessment, design of experiments (DoE), method control strategy, and method maintenance. Several aspects particular to partial least square (PLS) chemometric method development and validation (such as the combined use of DoE, optimization, and multivariate data analysis) are addressed. Results from the risk assessment showed that the active pharmaceutical ingredient (API) particle size was the most significant risk factor due to the presence of aggregates. This risk was reduced by introducing changes in the API crystallization procedure and by including a wide range of calibration blends within the expected range of particle size. Other potential risks related to the instrumentation, the API and excipient properties, and the environment were further studied and minimized. System suitability tests based on Mahalanobis distance and discriminant analysis (DA) techniques were developed to ensure the quality of the spectral data before blend potency calculation. The use of AQbD provided a robust and rugged method that has the potential to be used as part of the product real-time release (RTR) control strategy.

Temperature, pH and agitation rate as dissolution test discriminators of zofenopril calcium tablets

Comparative in vitro dissolution studies were performed on several tablet batches of zofenopril calcium, an ACE inhibitor, to determine if they could be differentiated on the basis of their release rates. The samples included six batches produced at Site 1 and one batch produced at Site 2. Using regular dissolution conditions (USP paddle method at a 50-rpm agitation speed in phosphate buffer, pH 7.5, at 37 degrees C), release rates of all the tablet batches were similar. By independently altering one of the dissolution test parameters, either a lower pH or a slower agitation rate, discrimination between the Site 1 and Site 2 tablets was enhanced. Discrimination was only slightly enhanced when a lower dissolution medium temperature was used. Tablets made from different polymorphs of zofenopril calcium could not be differentiated by their dissolution profiles, even with the more discriminating conditions. The dissolution profiles of certain other zofenopril calcium tablets (including film-coated vs uncoated tablets, and tablets made with micronized vs unmicronized drug particles) were indistinguishable using a 50-rpm agitation rate, but they could be clearly differentiated using a 40-rpm agitation rate.

Degradation of a Lyophilized Formulation of BMS-204352: Identification of Degradants and Role of Elastomeric Closures

The purpose of this study was to identify two degradation products formed in the parenteral lyophilized formulation of BMS-204352, investigate the possible role of elastomeric closures in their formation, and develop a strategy to minimize/control their formation. The first degradant was identified as the hydroxymethyl derivative (formaldehyde adduct, BMS-215842) of the drug substance formed by the reaction of BMS-204352 with formaldehyde. Structure confirmation was based on liquid chromatography/mass spectroscopy (LC/MS), nuclear magnetic resonance (NMR), and chromatographic comparison to an authentic sample of the hydroxymethyl degradation product, BMS-215842. To confirm the hypothesis that formaldehyde originated from the rubber closure, migrated into the product, and reacted with BMS-204352 drug substance to form the hydroxymethyl degradant, lyophilized drug product was manufactured, the vials were stoppered with two different rubber closure formulations, and its stability was monitored. The formaldehyde adduct degradant was observed only in the drug product vials stoppered with one of the rubber closures that was evaluated. Although formaldehyde has not been detected historically as leachable and is not an added ingredient in the rubber formulation, information obtained from the stopper manufacturer indicated that the reinforcing agent used in the stopper formulation may be a potential source of formaldehyde. The second degradant was identified as the desfluoro hydroxy analog (BMS-188929) based on LC/MS, NMR, and chromatographic comparison to an authentic sample of the desfluoro hydroxy degradation product.

Development of a Single In Vitro Dissolution Method for a Combination Trilayer Tablet Formulation of Clopidogrel and Pravastatin

A fixed-combination dose, trilayer tablet formulation was developed for two drugs already marketed as individual pr oducts, Plavix in which clopidogrel, an anti-clotting agent, is the active ingredient and pravastatin, an HMG-CoA reductase inhibitor for the treatment of hypercholesterolemia. To simplify quality control testing, the preference is to use a single dissolution method for the analysis of multiple active components in a combination tablet. However, development of one dissolution method for clopidogrel and pravastatin is particularly challenging because of the divergent pH solubility and pH dependent stability of these two drugs. At low pH (<3), clopidogrel bisulfate is most soluble and stable, whereas pravastatin sodium rapidly degrades due to lactonization and oxidation. Conversely, at a neutral pH and higher, pravastatin sodium is most soluble and stable, but clopidogrel bisulfate undergoes hydrolysis and racemization. This article describes the development of a single dissolution method to accommodate both drugs, including selection of medium pH and surfactant. The method uses USP Apparatus 2 (paddles) at 75 rpm in 1000 mL of citrate buffer (0.05 M, pH 5.5) medium containing 2% CTAB (cetyltrimethyl ammonium bromide, a cationic surfactant) at 37 °C. This dissolution methodology provides good dissolution profiles for both clopidogrel and pravastatin and is able to discriminate the changes in composition, manufacturing process, and stability for the combination tablets. To quantitate both drugs simultaneously, a rapid isocratic reversed-phase liquid chromatographic method was developed and validated.

AAPS Workshop on the Role of Dissolution in QbD and Drug Product Life Cycle: A Commentary

This is a summary report of the “AAPS Workshop on the Role of Dissolution in QbD and Drug Product Life Cycle” or ganized by the AAPS In Vitro Release and Dissolution Testing (IVDRT) Focus Group. Representatives from the pharmaceutical industry, regulatory authorities, and academia in the U.S. and Europe attended this workshop to discuss the role of dissolution in a Quality by Design (QbD) setting and its relevance in drug product development. Other areas of discussion included IVIVC/R and hot topics like alcohol dose-dumping. Numerous case studies were presented, and issues relevant to the dissolution scientist and areas needing further research were highlighted at this workshop. Views expressed in this paper are those of the participants from the industry and the agency and do not necessarily represent those of the FDA and USP.

Feasibility Study on Qualification of USP Dissolution Apparatus 1 and 2 Using the Enhanced Mechanical Calibration Procedure

A feasibility study was conducted in an analytical laboratory to evaluate implementation of the alternative procedure pr oposed by the FDA for enhanced mechanical calibration of USP dissolution Apparatus 1 and 2. The investigation started with a historical review of qualification data for more than 50 systems, generated through our current practice of combining USP mechanical calibration with the USP Performance Verification Test (PVT) using prednisone tablets. The data were compared with the more comprehensive FDA procedures and more stringent criteria for enhanced mechanical calibration. All the historical results met both USP and FDA criteria for shaft wobble, basket wobble, basket/paddle height check, and rotational speed and, in addition, passed the USP PVT. Shaft verticality was the mechanical parameter that infrequently did not meet the enhanced calibration criterion. Further investigations were conducted on a few representative dissolution systems to examine shaft verticality and determine what factors affect it. System levelness greatly affected whether shaft verticality met the tolerance. It is concluded from the results of the evaluation that it may be difficult for certain older units to consistently meet the criteria for shaft verticality. Therefore, our plan is to continue the current practice of a combination of USP mechanical calibration with PVT and to monitor shaft verticality data.