levorphanol and dihydrocodeine

Electrospray ionization (ESI) is the most widely used ionization method in on-line coupling of capillary electrophoresis-mass spectrometry (CE-MS). The conventional coaxial sheath flow electrospray interface is currently being replaced by the more sensitive nanoelectrospray technique. The usual limitation of nanoelectrospray CE-MS interface has been its short lifetime caused by deterioration of the metal coating on the CE capillary terminus. This article describes an easy way to construct a more durable and sensitive nanospray interface for nonaqueous CE-MS. In this approach a very thin glass spray capillary (ca. 30 microm outer diameter) is partly inserted inside the CE capillary, the junction being surrounded by the electrolyte medium, which is in contact with the platinum electrode. The interface was tested with five pharmaceuticals: methadone, pentazocine, levorphanol, dihydrocodeine, and morphine. Detection limits ranged from 12 to 540 fmol. Separation efficiency and reproducibility were also studied. The CE current was found to be stable and the migration times were highly reproducible. All the CE separations were carried out in a nonaqueous background electrolyte solution.

Topics: Codeine; Electrophoresis, Capillary; Equipment Design; Indicators and Reagents; Levorphanol; Methadone; Morphine; Pentazocine; Pharmaceutical Preparations; Sensitivity and Specificity; Spectrometry, Mass, Electrospray Ionization

The present study was designed to determine whether morphine-dependent rats have a decreased sensitivity to the cough-depressant effects of both opioid and nonopioid antitussives. Morphine dependence was induced by treatment with morphine-admixed food (0.5 mg/g of food) for 7 days. The cough reflex was induced by application of electrical stimulation to the tracheal mucosa by the puncture electrode-induced cough method. The cough-depressant effect was evaluated as the antitussive ED50 calculated by the method of Litchfield and Wilcoxon. The effects of both opioid (morphine and dihydrocodeine) and nonopioid (dextromethorphan and noscapine) antitussive drugs were diminished in morphine-dependent rats. The values of ED50 of these antitussive drugs in morphine-dependent rats were about 3-fold higher than those in control rats. A significantly lower number of serotonin receptors was found in the brainstem of morphine-dependent rats (Bmax: 2.88 +/- 0.32 pmoles/mg protein) than in controls (Bmax: 4.93 +/- 0.50 pmoles/mg protein). It is possible that the decreased sensitivity to both opioid and nonopioid antitussive drugs, in terms of the depression of the cough reflex, in morphine-dependent rats may be due to changes in the number of serotonin receptors.

Topics: Animals; Antitussive Agents; Brain Stem; Codeine; Cough; Dextromethorphan; Levorphanol; Male; Morphine; Noscapine; Rats; Rats, Inbred Strains; Receptors, Serotonin