A simple and universal headspace GC-FID method for accurate quantitation of volatile amines in pharmaceuticals.

Volatile amines are reagents commonly used in pharmaceutical manufacturing of intermediates, active pharmaceutical ingredients (APIs), and drug products as participating regents for chemical reactions and optimization of product yield. Due to their compound specific daily allowable intake, residual volatile amines are required by regulatory agencies to be monitored and controlled in pharmaceutical products intended for human consumption. However, the accurate quantification of residual volatile amines in pharmaceutical entities can often be challenging as these analytes may chemically react and/or interact with the sample matrix. Herein, we describe a simple and universal headspace gas chromatography with flame ionization detection (HS-GC-FID) method capable of separating 14 commonly used volatile amines. The chemical activity of the volatile amines with the API matrix were mitigated by using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as an additive to reduce matrix effects in conventional high-boiling diluents. The addition of DBU drastically improved the detectability and method accuracy of the residual volatile amines in an acidic API, namely, Ketoprofen®. Additionally, DBU was employed as a GC deactivation reagent to ensure interfacial adsorption of the analytes to GC components were reduced, thereby improving method precision. Method validation showed acceptable linearity, limit of detection, limit of quantitation, solution stability, precision, and robustness. Separation specificity, evaluated by observing the chromatographic resolution of the volatile amines with one-another and against a set of 23 common residual solvents, were shown to be acceptable for most peak pairs.

High-throughput determination of OROS drug release rate profile using micro parallel liquid chromatography.

A high throughput method with the use of micro parallel liquid chromatography (microPLC) technique was first applied for the determination of drug release profiles in OROS tablets. Currently, high-performance liquid chromatography (HPLC) is a preferred analytical tool to analyze samples released from OROS tablets. However, it usually takes more than 20 h to analyze a large number of release rate samples and generate a release-rate profile. In this study, with the use of a 24-column Brio cartridge, the microPLC enabled simultaneous analysis of 24 release-rate samples. The total analysis time including the generation of the release-rate profile was greatly reduced to 3 h. Two different OROS formulations were used to compare the drug release testing using both microPLC and conventional HPLC. The drug release profiles generated using microPLC were comparable with those obtained by HPLC. In addition, the reproducibility and sensitivity of microPLC analysis were examined. Overall, significant reductions in analysis time and solvent consumption were the major advantages of using microPLC in profiling the drug release rate for a controlled-release dosage.

Reduced toxicity and superior therapeutic activity of a mitomycin C lipid-based prodrug incorporated in pegylated liposomes.

PURPOSE: A lipid-based prodrug of mitomycin C [MMC; 2,3-(distearoyloxy)propane-1-dithio-4'-benzyloxycarbonyl-MMC] was designed for liposome formulation. The purpose of this study was to examine the in vitro cytotoxicity, pharmacokinetics, in vivo toxicity, and in vivo antitumor activity of this new lipid-based prodrug formulated in polyethylene glycol-coated (pegylated) liposomes. EXPERIMENTAL DESIGN: MMC was released from the MMC lipid-based prodrug (MLP) by thiolytic-induced cleavage with a variety of thiol-containing reducing agents. MLP was incorporated with nearly 100% efficiency in cholesterol-free pegylated liposomes with hydrogenated phosphatidylcholine as the main component and a mean vesicle size of approximately 90 nm. This formulation was used for in vitro and in vivo tests in rodents. RESULTS: In vitro, the cytotoxic activity of pegylated liposomal MLP (PL-MLP) was drastically reduced compared with free MMC. However, in the presence of reducing agents, such as cysteine or N-acetyl-cysteine, its activity increased to nearly comparable levels to those of free MMC. Intravenous administration of PL-MLP in rats resulted in a slow clearance indicating stable prodrug retention in liposomes and long circulation time kinetics, with a pharmacokinetic profile substantially different from that of free MMC. In vivo, PL-MLP was approximately 3-fold less toxic than free MMC. The therapeutic index and absolute antitumor efficacy of PL-MLP were superior to that of free MMC in the three tumor models tested. In addition, PL-MLP was significantly more active than a formulation of doxorubicin in pegylated liposomes (DOXIL) in the M109R tumor model, a mouse tumor cell line with a multidrug-resistant phenotype. CONCLUSIONS: Delivery of MLP in pegylated liposomes is a potential approach for effective treatment of multidrug-resistant tumors while significantly buffering the toxicity of MMC.

Ion chromatography for the determination of sulfate in STEALTH liposomes.

An ion chromatography (IC) method has been validated for the assay of sulfate ion content in the STEALTH liposome drug-delivery system (ALZA, Mountain View, CA, USA), which contains ammonium sulfate as an excipient. This method contains two assays. One assay determines the total sulfate ion content; the other determines the external sulfate ions. The total sulfate ion analysis measures the sulfate ion content of the formulation, inside and outside of the liposome. The analysis includes the disruption of the liposome bilayer with Triton-X, followed by dilution with 10% sucrose, and analysis using IC. The external sulfate analysis measures sulfate ions outside the liposome without disrupting the liposome structure. A neat sample of STEALTH liposome drug-delivery system is filtered through a 0.02 microm filter, and the filtrate is analyzed by IC. Sulfate ion is resolved on an anion exchange column and detected by a conductivity detector. Quantitation is performed by linear regression analysis of peak areas from a standard curve of sulfate ion containing at least five standard points. The method was validated for specificity, linearity, accuracy/recovery, precision, and stability of the standard and the sample. The validated method has been applied to the quantification of sulfate ion in STEALTH liposomes for product release and stability testing.