The effect of naloxone given at various times after morphine administration on the development of tolerance to and dependence on a single dose of morphine was studied. Naloxone antagonized the analgesic effect of morphine and the development of tolerance to and dependence on morphine, dose dependently. The time course of the development of tolerance to a single dose of morphine almost parallele...

After epidural administration of 15 mg 3, 6-dinicotinoylmorphine (nicomorphine) in 10 patients undergoing pulmonary surgery, the parent compound was quickly metabolized into the metabolites 6-mononicotinoylmorphine and morphine. The mean apparent half-lives (+/- SD) of elimination were 10 min (0.165 h +/- 0.053 h) for 3,6-dinicotinoylmorphine and 1.77 h +/- 1.23 h for 6-mononicotinoylmorphine. ...

The bioavailability of oral controlled release morphine tablets (MST, Napp Laboratories) and oral morphine sulphate in aqueous solution (MSS) was compared in 10 patients with advanced cancer. Serum samples were analysed for morphine, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) using a specific HPLC assay. The relative bioavailability of morphine with MST was significantly less...

The opponent-process theory posits that the aversive state of acute opiate withdrawal is a consequence of, and depends on, the previous rewarding state evoked by acute morphine reward. Although the brainstem tegmental pedunculopontine nucleus (TPP) is crucial for the rewarding component of morphine, the source of the later aversive component is not known. It is possible that (i) the second aver...

Our previous studies have shown that morphine withdrawal induced an increase in the expression of protein kinase (PK) A and mitogen-activated extracellular kinase (MAPK) pathways in the heart during morphine withdrawal. The purpose of the present study was to evaluate the interaction between PKA and extracellular signal-regulated kinase (ERK) signaling pathways mediating the cardiac adaptive ch...

BACKGROUND Morphine and lidocaine are known to influence the perception of pain. The present study sought to determine the influence of local administration of morphine on lidocaine-induced analgesia in morphine non-dependent (MND), morphine dependent (MD) and morphine withdrawal (MW) animals. METHODS Adult male Wistar rats were divided into four groups: Control, MND, MD and MW rats. Lidocain...

The contribution of fetal metabolism to drug disposition in pregnancy is poorly understood. With maternal administration of morphine, like many drugs, steady-state concentrations in fetal plasma are less than in maternal plasma. The contribution of fetal metabolism to this difference is unknown. Morphine was used as a model drug to test the hypothesis that fetal metabolism contributes significa...

BACKGROUND/AIM It is known that bile acids improve the absorption, bioavailability and pharmacodynamic characteristics of some drugs. Morphine analgesia is produced by activation of opioid receptors within the central nervous system (CNS) at both spinal and supraspinal levels. Since a morphine molecule contains 3 polar groups and therefore hard to transfer through the blood-brain barrier, the a...

An assay technique, homogeneous enzyme immunoassay, is described for the quantitative determination of morphine derivatives in biological fluids. An enzyme is labeled with morphine. When the enzymelabeled morphine is bound by antimorphine antibodies, the enzyme is rendered inactive. Free morphine competes with enzyme-morphine for antibody binding sites preventing inhibition of enzyme activity. ...

BACKGROUND Many clinical and experimental studies have suggested that diabetes or hyperglycemia alter opioid responsiveness. However, little information is available on the effects of diabetes mellitus on opioid requirements in the postoperative period. METHODS Sixty-four patients scheduled for elective, total abdominal hysterectomy were included into this prospective study to evaluate the ef...