Complexities of particulate matter measurement in parenteral formulations of small-molecule amphiphilic drugs.

Reconstituted parenteral solutions of three surface-active anti-infective small-molecule drugs and solutions of sodium dodecyl sulfate (SDS, a model surfactant) were studied to quantify the impact of sample preparation and handling on particle counts. Turbidimetry and light obscuration profiles were recorded as a function of agitation and shearing with and without the introduction of foam into the solutions. SDS solutions at concentrations above the critical micelle concentration (CMC) show significantly greater sensitivity to shear and foam presence than SDS solution below the CMC: Values of >10 µm particles increased 8 fold over control (an unsheared sample) in the micellar solution vs. 4 fold particle count increase over control at a sub-micellar concentration. An even more significant increase in the ratio of particle count in sheared/unsheared solution is seen for >25 µm unit counts, due to the increased interference of foam with the measurement. Two commercial products, injection formulations of teicoplanin and cefotaxime sodium, as well as an investigational compound 1, showed an increase in scattering as a function of foam production. The impact of foaming was significant, resulting in an increase of turbidity and light obscuration measurements in all solutions. The results illustrate some of the challenges that are inherent to optically clear, homogeneous pharmaceutical injections containing compounds which have a tendency toward self-association and surfactant-like behavior.

Compatibility of ceftobiprole medocaril with selected drugs during simulated Y-site administration.

PURPOSE: The physical compatibility of the new cephalosporin ceftobiprole medocaril with 70 other drugs during simulated Y-site injection was studied. METHODS: Ceftobiprole was reconstituted with sterile water for injection. Dilutions of ceftobiprole 2 mg/mL (as ceftobiprole medocaril 2.67 mg/mL) were prepared in 5% dextrose injection, 0.9% sodium chloride injection, and lactated Ringer's injection. For testing compatibility with the other drugs, a 5-mL sample of the ceftobiprole 2-mg/mL admixtures was combined with a 5-mL sample of the other drug either undiluted or diluted with one of the three vehicles. Each combination was prepared in duplicate, switching the order of drug addition, and kept at room temperature. At intervals up to four hours after preparation, samples were examined visually and with the aid of a Tyndall beam and measured with a turbidimeter and a particle sizer and counter. Compatibility with propofol was evaluated by checking for emulsion separation and particles after centrifugation. RESULTS: In all three vehicles, ceftobiprole was compatible with 31 other drugs and incompatible with 32. With 7 drugs, compatibility was dependent on the vehicle used. Signs of incompatibility included the presence of visible and subvisible particles, haze, and turbidity. No incompatibilities were related to the order of mixing. CONCLUSION: Of the 70 drugs evaluated for compatibility with ceftobiprole 2 mg/ mL (as medocaril) in 5% dextrose injection, 0.9% sodium chloride injection, and lactated Ringer's injection, 31 were found to be compatible and 32 were found to be incompatible in all three of the infusion solutions. For 7 of the drugs, compatibility was dependent on which infusion solution was used. Ceftobiprole medocaril should not be simultaneously administered via a Y site with drugs with which it was shown to be incompatible.

Micellar electrokinetic chromatography-electrospray ionization mass spectrometry for the identification of drug impurities.

Previously, we have presented a system hyphenating continuous micellar electrokinetic chromatography (MEKC) with electrospray ionization mass spectrometry (ESI-MS). Here we evaluate this technique for its applicability in impurity profiling of drugs using galantamine and ipratropium as test samples. A background electrolyte (BGE) of 10mM sodium phosphate (pH 7.5), 12.5-15% acetonitrile and 20mM sodium dodecylsulfate (SDS) was used for the MEKC-MS analysis of a galantamine sample containing a number of related impurities, and a heat-treated solution of ipratropium containing a number of unknown degradation products. MEKC provided efficient separation of all sample constituents. Despite the presence of non-volatile BGEs, all impurities in the galantamine sample could be detected by ESI-MS in their respective extracted ion traces (XICs) with a detection sensitivity in the sub-microg/ml range (full-scan mode). MS/MS detection provided useful product spectra allowing the structural characterization of the respective galantamine impurities. With the MEKC-MS/MS system, two degradation products could be revealed and identified in the heat-stressed ipratropium sample. The presented method shows good potential for the detection and structure elucidation of minor impurities in drug substances.

Interlaboratory study of a NACE method for the determination of R-timolol content in S-timolol maleate: assessment of uncertainty.

Analyses of statistical variance were applied to evaluate the precision and practicality of a CD-based NACE assay for R-timolol after enantiomeric separation of R- and S-timolol. Data were collected in an interlaboratory study by 11 participating laboratories located in Europe and North America. General qualitative method performance was examined using suitability descriptors (i.e. resolution, selectivity, migration times and S/N), while precision was determined by quantification of variances in the determination of R-timolol at four different impurity levels in S-timolol maleate samples. The interlaboratory trials were designed in accordance with the ISO guideline 5725-2. This allowed estimating for each sample, the different variances, i.e. between-laboratory (s2(Laboratories)), between-day (s2(Days)) and between-replicate (s2(Replicates)). The variances of repeatability (s2r) and reproducibility (s2R) were then calculated. The estimated uncertainty, derived from the precision estimates, seems to be concentration-dependent above a given threshold. This example of R-timolol illustrates how a laboratory can evaluate uncertainty in general.

Capillary electrophoresis-mass spectrometry in impurity profiling of pharmaceutical products.

Generally reversed-phase high-performance liquid chromatography (RP-HPLC) methods are extensively applied during quality control of pharmaceutical products. Since capillary electrophoresis (CE) is based on a different separation principle and consequently results in a unique selectivity compared to RP-HPLC, it can advantageously be used as an orthogonal technique. CE equipped with a mass spectrometer detector provides even more information that can be helpful for identification and structural elucidation purposes. CE-MS was recently implemented in the method development approach to support impurity profiling of pharmaceutical products. In this paper the application of CE-electrospray ionization (ESI)-MS/MS to the impurity profiling of galantamine hydrobromide in stressed Reminyl Extended Release (ER) capsules is discussed. Reminyl ER samples were stressed at different storing conditions. The impurity profile of these samples was compared with the current RP-HPLC and chiral CE method, but also with CE-ESI-MS/MS. The combination of these three methods provided valuable data that allowed understanding comprehensively the impurity profile of these samples. Two impurities were detected at concentrations lower than 0.05%, which did not occur in nonstressed samples. Chromatographic data and the fragmentation patterns of galantamine and related compounds were also examined for identification of these two degradation products.