The development and stability assessment of extemporaneous pediatric formulations of Accupril.

Quinapril, the active ingredient in Accupril tablets, is an ACE inhibitor used to treat hypertension. Quinapril is unstable in aqueous solution and therefore the development of a liquid formulation is a significant challenge. Previous studies show the rate of degradation of quinapril into its two major degradants to be pH dependent, indicating the parent compound to be most stable in the narrow pH range of 5.5-6.5. Accupril (20 mg) and readily available pharmaceutical components were combined to generate three formulations that are stable for at least 28 days, possess acceptable appearance, and are palatable to pediatric patients. To combat the presence of magnesium carbonate in the Accupril tablets, which increase the pH of the solution above 6.5, several pharmaceutically available buffers were incorporated. Nine prototypes were developed and their characteristics evaluated after 1 week under stressed conditions. The three that most closely matched the stability criteria were chosen for a definitive stability study. A stability-indicating method was developed and validated for these studies. All three formulations met the following specifications when stored at 5 degrees C for 6 weeks; Quinapril remained >or=90% intact and the two known degradants did not reach values >or=3.0% individually or >or=5.0% combined.

Improving the detection of degradants and impurities in pharmaceutical drug products by applying mass spectral and chromatographic searching.

Liquid chromatography/mass spectrometry (LC/MS) and NMR are commonly used to identify metabolites, impurities and degradation products in the pharmaceutical industry. To more efficiently deal with the large volumes of data these techniques generate, software programs have been developed by various vendors to assist in the identification of these compounds through the use of spectral and chromatographic search algorithms. The feasibility of using such programs for detecting drug degradants and impurities is assessed. A number of compounds encompassing a wide range of both chemical and pharmaceutical properties were tested using LC/UV/MS and the spectral/chromatographic search algorithm MetaboLynx (Micromass UK Ltd.) to determine the feasibility of detecting analytes at low concentrations. In addition, drug product and stressed drug substance samples containing quinapril hydrochloride, the active ingredient in Accupril tablets, were determined by liquid chromatography with atmospheric pressure ionization-time-of-flight (API LC-TOF) and an API LC-quadrupole (Q) mass spectrometer, and the resulting data was processed using MetaboLynx. The ability of this program to detect and list a variety of analytes known to be present in the samples was evaluated. The combination of LC/UV, LC/MS and spectral/chromatographic searching is a valuable tool for the detection of impurities at low levels.

Quantitative bioanalysis of enantiomeric drugs using capillary electrophoresis and electrospray mass spectrometry.

A novel assay method for an enantiomeric pair of drugs has been developed using a combination of capillary electrophoresis and electrospray tandem mass spectrometry connected with a homemade interface. Accurate quantification was demonstrated in plasma from 0.25 to 50 microg/ml. A liquid-liquid sample preparation technique allowed improvement in the quantitation limit to 10 ng/ml. Variables for the enantiomeric separation, including chiral selective reagent, organic solvents, buffer and acid concentration as well as injection technique, were optimized. This assay proved adequate for analysis of neat, spiked plasma, and plasma from a pharmacological study of the drug enantiomers.

Integrating automation and LC/MS for drug discovery bioanalysis.

A novel, integrated approach for automated sample handling in drug discovery bioanalysis is described. The process includes aspects of animal study design, biological sample collection, sample processing and high-throughput APILC/MS operating in under multiple reaction monitoring (MRM). A semi-automated 96-well liquid-liquid extraction technique for biological fluid sample preparation was developed and used in conjunction with the integrated sample-handling approach. One plate of samples could be prepared within 1.5 h compared with 4 h for a manual approach, and the resulting 96-well plate of extracts was directly compatible with the LC/MS. Feasibility studies for the development of the process included sample collection map generation and information management, sample collection formatting, evaluation of alternative dilution schemes for high-concentration samples, choice of biological fluid, and evaluating the capabilities of the two liquid-handling workstations. Numerous comparisons between the new approach and conventional sample-handling approaches gave equivalent drug-quantitation results for several example compounds. This new sampling process has approximately doubled the efficiency (as measured by studies assayed per month) of drug discovery bioanalysis in our laboratory. The approach was also used in conjunction with time-of-flight mass spectrometry instrumentation (LC/TOF/MS) to quantify and characterize the disposition of simultaneously dosed example drug compounds in the rat. Likely strategies for future automated sample preparation workstations are described.