Isolation and identification of a degradation product in a capsule formulation containing the elastase inhibitor, DMP 777.

An unexpected degradation product, greater than 0.10%, was observed in a DMP 777 capsule formulation stored at 40 degrees C/75% r.h. for 3 months and 25 degrees C/60% r.h. for 2 years. The degradant of interest was prepared in quantity by refluxing the drug substance in dilute acid. A preparative HPLC method was developed to separate the various degradants and to collect each as a separate fraction. Each fraction was analyzed by the analytical HPLC gradient test method to assure positive identification of each peak and to correlate each peak to the original capsule sample. Key isolated degradation products were used for structure elucidation with mass spectrometry and NMR. The major degradant of interest in the capsule formulation was found to be a carboxylic acid resulting from the acid hydrolysis of an amide bond.

Pharmaceutical development and specification of stereoisomers.

The pharmaceutical development of chiral drugs requires the activities of many different research and development groups. Guidelines which help to coordinate the activities of these groups and assist in the successful development of compounds with either single or multiple chiral centers are outlined and discussed.

Determination of raffinose and lactobionic acid in ViaSpan by anion exchange chromatography with pulsed amperometric detection.

An anion exchange chromatographic method has been developed to quantify raffinose and lactobionic acid in ViaSpan, an organ preservation product. Separation was accomplished using an aqueous sodium hydroxide/acetate solvent system (pH 13) on a Carbopac PA1 column. Detection was performed using a pulsed amperometric detector equipped with a gold working electrode. The method was able to resolve raffinose,lactobionic acid and other ingredients in the ViaSpan product. Validation testing of the method for routine use produced excellent linearity, precision and accuracy. The limits of detection for raffinose and lactobionic acid were 1.0 ng (1.7 x 10(-12) mol, S/N = 3) and 2.0 ng (5.6 x 10(-12) mol, S/N = 3) respectively. The total analysis time is less than 15 min.

Stability of nicardipine hydrochloride in intravenous solutions.

The stability of nicardipine hydrochloride in large-volume i.v. solutions was studied. Admixtures of nicardipine hydrochloride 0.05 and 0.5 mg/mL were prepared in 5% dextrose and 0.45% sodium chloride injection, 5% dextrose and 0.9% sodium chloride injection, 0.45% sodium chloride injection, 0.9% sodium chloride injection, 5% dextrose and lactated Ringer's injection, 5% dextrose injection, lactated Ringer's injection, 5% sodium bicarbonate injection, and 5% dextrose injection with potassium chloride 40 meq/L. Two glass and two polyvinyl chloride (PVC) containers of each solution were prepared and stored at ambient room temperature under normal fluorescent light. Samples were removed and tested for nicardipine concentration by stability-indicating high-performance liquid chromatography at 0, 24, 48, and 72 hours and seven days. Testing included visual checking and optical density measurements. The admixtures remained clear and slightly yellow except for nicardipine hydrochloride in sodium bicarbonate injection, which showed immediate precipitation, and nicardipine hydrochloride in lactated Ringer's injection, which increased in optical density at 400 nm over time. There were no significant changes in nicardipine concentrations in nicardipine concentrations in glass containers. Admixtures stored in PVC containers showed a slow, constant decline in nicardipine concentrations, sometimes to less than 85% of the initial drug concentration within 24 hours, except for nicardipine hydrochloride in lactated Ringer's injection or 5% dextrose and lactated Ringer's injection, which showed an immediate and continuing rapid loss. Nicardipine hydrochloride 0.5 and 0.05 mg/mL in eight i.v. solutions was stable in glass containers for up to seven days. Drug concentrations slowly decreased in PVC containers. The drug was not stable in 5% sodium bicarbonate injection or in PVC bags containing lactated Ringer's injection or 5% dextrose and lactated Ringer's injection.

Degradation kinetics and mechanisms of moricizine hydrochloride in acidic medium.

The degradation kinetics of moricizine hydrochloride (1) were examined over a pH range of 0.6 to 6.0 at an ionic strength of 0.3 and 60 degrees C. The disappearance of intact 1 was followed by a stability-indicating HPLC assay. The degradation products, which had approximate solubilities of less than 100 micrograms/mL, precipitated in aqueous solution. The precipitate was collected for HPLC analysis and identification of degradation products. Degradation of 1 was catalyzed by acetate and phosphate buffers and was pH dependent, with the pH of the minimum rate constant located between 2.8 and 3.2. At pH 0.6-2.0, 1 degraded via amide hydrolysis to yield first ethyl (10H-phenothiazin-2-yl) carbamate (2), an amide hydrolysis product, which further oxidized in parallel to give ethyl (3-oxo-3H-phenothiazin-2-yl) carbamate (3), ethyl (10H-phenothiazin-2-yl) carbamate S-oxide (4), and diethyl (3,10'-bi-10H-phenothiazine-2,2'-diyl)bis(carbamate) (5), the dimer of the amide hydrolysis product. At pH 2.2-6.0, 1 degraded via a reverse Mannich reaction, to form the reverse Mannich product ethyl [10-(1-oxo-2-propenyl)-10H-phenothiazin-2-yl] carbamate (6), and by parallel reaction via the described amide hydrolysis pathway. The dimer of the amide hydrolysis product was not detectable at pH greater than 2.8. At pH greater than 4.0, the reverse Mannich product was the predominant degradation product. Degradation of 1 was subject to positive and negative kinetic salt effects at pH 1.0 and 4.0, respectively. Arrhenius plots determined at pH 1.0 and 6.0 were linear between 37 and 70 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of nitro-polycyclic aromatic hydrocarbons in liquid chromatography by zinc reduction and peroxyoxalate chemiluminescence.

Detection limits in the range 0.25-8.5 pg have been obtained for nitro-polycyclic aromatic hydrocarbons (nitro-PAHs) in high-performance liquid chromatography (HPLC). The nitro-PAHs are reduced on-line to the corresponding amino-PAHs and detected by peroxyoxalate chemiluminescence. Quantitative reduction is achieved on a short (3.5 X 0.32 cm) column packed with a 1:1 mixture of glass beads (ca. 40 micron) and zinc particles (40-80 micron). The mobile phase consists of 70-80% acetonitrile, the balance being a 50-mM tris(hydroxymethyl)aminomethane hydrochloride (pH 6.5) buffer, which is necessary both for the reduction and for catalysis of the chemiluminescent reaction. The amino-PAHs are excited by energy transfer from the decomposition products of the reaction between hydrogen peroxide and bis(2,4,6-trichlorophenyl)oxalate. These reagents are introduced by post-column mixing, and the emission is detected by means of a conventional fluorescence detector with its light source turned off. We reported the high sensitivity and selectivity of peroxyoxalate chemiluminescence toward amino-PAHs in earlier work. The method yields a linear response over at least three orders of magnitude, and in most cases the detection limits are better than those obtained by fluorescence detection with the same fluorometer. The reduction column may be placed either before or after the analytical column, so that the analytes are eluted either as the nitro-PAHs or the corresponding amino-PAHs. This feature provides a second characteristic retention time and is useful in identifying the detected compounds. The technique has been applied to the selective detection of nitro-PAHs in carbon black. The carbon black samples were Soxhlet extracted with toluene, evaporated to dryness, and the extracts redissolved in methylene chloride for direct injection into the HPLC column. The principal compounds found in the carbon black samples were poly-substituted nitro-PAHs and unsubstituted PAHs. This method provides a sensitive and selective method for the analysis of complex samples for these environmentally important mutagens.