Ethyl Tropic Acid - CAS 3979-14-4

In vivo and in vitro metabolism of scopolamine is investigated using a highly specific and sensitive liquid chromatography-mass spectrometry (LC-MSn) method. Feces, urine, and plasma samples are collected individually after ingestion of 55 mg/kg scopolamine by healthy rats. Rat feces and urine samples are cleaned up by a liquid-liquid extraction and a solid-phase extraction procedure (C18 cartridges), respectively. Methanol is added to rat plasma samples to precipitate plasma proteins. Scopolamine is incubated with homogenized liver and intestinal flora of rats in vitro, respectively. The metabolites in the incubating solution are extracted with ethyl acetate. Then these pretreated samples are injected into a reversed-phase C18 column with mobile phase of methanol-ammonium acetate (2 mM, adjusted to pH 3.5 with formic acid) (70:30, v/v) and detected by an on-line MSn system. Identification and structural elucidation of the metabolites are performed by comparing their changes in molecular masses (DeltaM), retention-times and full scan MSn spectra with those of the parent drug. The results reveal that at least 8 metabolites (norscopine, scopine, tropic acid, aponorscopolamine, aposcopolamine, norscopolamine, hydroxyscopolamine, and hydroxyscopolamine N-oxide) and the parent drug exist in feces after administering 55 mg/kg scopolamine to healthy rats. Three new metabolites (tetrahydroxyscopolamine, trihydroxy-methoxyscopolamine, and dihydroxy-dimethoxyscopolamine) are identified in rat urine. Seven metabolites (norscopine, scopine, tropic acid, aponorscopolamine, aposcopolamine, norscopolamine, and hydroxyscopolamine) and the parent drug are detected in rat plasma. Only 1 hydrolyzed metabolite (scopine) is found in the rat intestinal flora incubation mixture, and 2 metabolites (aposcopolamine and norscopolamine) are identified in the homogenized liver incubation mixture.

Aim:To establish a LC-MS(n) method for the identification of anisodamine and its metabolites in rat feces.Methods:Feces samples were collected after single administration of 25 mg x kg(-1) anisodamine to rats, and dipped in water for 1 h. Samples were then extracted by ethyl acetate. The pretreated samples were separated on a reversed-phase C18 column using a mobile phase of methanol / 0.01% triethylamine (adjusted to pH 3.5 with formic acid) (60 : 40, v/v) and detected by LC-MS". Identification of the metabolites and elucidation of their structures were performed by comparing their changes in molecular masses (deltaM), retention-times and full scan MS(n) spectra with those of the parent drug and blank feces.Results:The parent drug and its seven metabolites (6beta-hydroxytropine, nor-6beta-hydroxytropine, aponoranisodamine, apoanisodamine, noranisodamine and hydroxyanisodamine, tropic acid) were found in rat feces.Conclusion:This method is sensitive, rapid, simple, effective, and suitable for the rapid identification of drug and its metabolites in biologic samples.

Hydroxyurea is an antineoplastic drug, which is also widely used in the treatment of sickle cell disease. Various methods including colorimetry, high performance liquid chromatography, and gas chromatography-mass spectrometry (GC-MS) are available for the assay of hydroxyurea. In the gas chromatography method described, the drug is extracted from serum, plasma, or urine using ethyl acetate and phosphate buffer (pH 6). The organic phase containing drug is separated and dried under a stream of nitrogen. After trimethylsilyl derivatization, samples are analyzed using GC-MS. Quantitation of the drug in a sample is achieved by comparing responses of the unknown sample to the responses of the calibrators using selected ion monitoring. Tropic acid is used as an internal standard.