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Ying Lung Tseng - One of the best experts on this subject based on the ideXlab platform.

  • confirming urinary excretion of Mephentermine and phentermine following the ingestion of oxethazaine by gas chromatography mass spectrometry analysis
    Journal of Analytical Toxicology, 2010
    Co-Authors: Weihsun Huang, Ying Lung Tseng
    Abstract:

    Mephentermine and phentermine, substances prohibited in sports by the World Anti-Doping Agency, were found for the first time in urine specimens following the administration of a therapeutic medication, oxethazaine. In a recent sporting event, a urine specimen donor who tested positive for Mephentermine and phentermine claimed consumption of Mucaine ® for treating stomach pain was the reason for testing positive. Five volunteers were administrated oxethazaine (a topical anesthetic found in the multi-ingredient medication Mucaine and its generic equivalent, Stoin, both of which are available inTaiwan), Mephentermine, and phentermine. Excretion profiles of Mephentermine and phentermine following the administration of these drugs were found to be similar. However, the Mephentermine/phentermine ratios found in urine specimens collected at different time points following the administration of oxethazine and Mephentermine were found to be characteristically different.

Hiroshi Kozuka - One of the best experts on this subject based on the ideXlab platform.

  • intestinal metabolism of Mephentermine and its biliary metabolites in male wistar rats
    Xenobiotica, 1992
    Co-Authors: Masaaki Mori, T Miyahara, M Kobayashi, Hiromi Uemura, Hiroshi Kozuka
    Abstract:

    1. Intestinal metabolites produced in the incubation (0–24 h) of Mephentermine (MP), phentermine (Ph), N-hydroxyMephentermine (N-hydroxy-MP), N-hydroxyphentermine (N-hydroxy-Ph), p-hydroxyMephentermine (p-hydroxy-MP) and p-hydroxyphentermine (p-hydroxy-Ph) with male Wistar rat intestinal contents under N2 were examined by g.l.c. and g.l.c.-electron impact (EI) mass spectrometry. Metabolites produced in the anaerobic incubation of bile from rats given MP, with the intestinal contents were also examined. In addition, urinary and biliary metabolites of p-hydroxy-MP and p-hydroxy-Ph dosed orally to rat were examined.2. Metabolites in the anaerobic incubation of N-hydroxy-MP and N-hydroxy-Ph were MP and Ph, and Ph, respectively. No metabolites were detected in the incubation of MP, Ph, p-hydroxy-MP and p-hydroxy-Ph.3. p-Hydroxy-MP and p-hydroxy-Ph (major), and MP and Ph (minor) were detected when bile from rats given MP was incubated with intestinal contents.4. Unchanged p-hydroxy-MP, and conjugates of p-hydro...

  • isolation of urinary p hydroxylated metabolites of Mephentermine and phentermine in male wistar rats
    Xenobiotica, 1990
    Co-Authors: Masaaki Mori, N Uyyu, K Sakai, Masami Inoue, T Miyahara, Hiroshi Kozuka
    Abstract:

    1. p-HydroxyMephentermine (p-hydroxy-MP) and p-hydroxyphentermine (p-hydroxy-Ph) were isolated as hydrochlorides from urine of male Wistar rats repeatedly dosed with Mephentermine (MP). In addition, p-hydroxy-Ph was isolated as the hydrochloride from urine of the rats dosed with phentermine (Ph).2. These results substantiate previous indications that p-hydroxylation of MP and Ph was a primary metabolic reaction in the rat.

Masaaki Mori - One of the best experts on this subject based on the ideXlab platform.

  • Metabolism of Mephentermine in male guinea pigs and male mice
    Xenobiotica, 2008
    Co-Authors: Masaaki Mori, M Kobayashi, K Nakafuku, Y Yumoto, T Miyahara, H Kozuka
    Abstract:

    1. Urinary metabolites of Mephentermine (MP), after i.p. administration of MP to male Hartley guinea pigs and mice, were identified by g.l.c.-electron impact (El) mass spectrometry. Excretion of urinary radioactivity, and metabolites of 3H-MP, after i.p. administration, were determined by preparative t.l.c.-liquid scintillation counting.2. About 27% of the radioactivity administered was excreted in the 24 h urine of guinea pigs, and 36% dose was excreted in 5 days. In mice, about 47% of the radioactivity was excreted in the 24 h urine, and 52% in 5 days.3. Excretion rates of metabolites detected in the 24 h urine of guinea pigs were phentermine (Ph, 7.8%), a conjugate of N-hydroxyphentermine (N-hydroxy-Ph, 3.6%), p-hydroxyphentermine (p-hydroxy-Ph, 1.0%) and its conjugate (2.9%), and other metabolites (conjugates of MP and Ph, N-hydroxyMephentermine (N-hydroxy-MP) and its conjugate, p-hydroxyMephentermine (p-hydroxy-MP) and its conjugate, and N-hydroxy-Ph;

  • the formation of metabolites of Mephentermine by microsomal and cytosolic preparations of male wistar rat livers
    Xenobiotica, 1992
    Co-Authors: Masaaki Mori, K Sakai, M Kobayashi, K Nakafuku, Y Mori, H Kozuka
    Abstract:

    1. Metabolites of Mephentermine (MP), phentermine (Ph), p-hydroxy-MP, p-hydroxy-Ph, N-hydroxy-MP and N-hydroxy-Ph on incubation with rat liver microsomal and cytosolic preparations were identified by g.l.c. and g.l.c.-mass spectrometry.2. Identification of the metabolites indicated the following new metabolic routes of MP: NADPH-dependent microsomal formation of p-hydroxy-MP from MP, of p-hydroxy-Ph from p-hydroxy-MP, and the NADH-dependent microsomal formation of Ph from N-hydroxy-Ph.

  • intestinal metabolism of Mephentermine and its biliary metabolites in male wistar rats
    Xenobiotica, 1992
    Co-Authors: Masaaki Mori, T Miyahara, M Kobayashi, Hiromi Uemura, Hiroshi Kozuka
    Abstract:

    1. Intestinal metabolites produced in the incubation (0–24 h) of Mephentermine (MP), phentermine (Ph), N-hydroxyMephentermine (N-hydroxy-MP), N-hydroxyphentermine (N-hydroxy-Ph), p-hydroxyMephentermine (p-hydroxy-MP) and p-hydroxyphentermine (p-hydroxy-Ph) with male Wistar rat intestinal contents under N2 were examined by g.l.c. and g.l.c.-electron impact (EI) mass spectrometry. Metabolites produced in the anaerobic incubation of bile from rats given MP, with the intestinal contents were also examined. In addition, urinary and biliary metabolites of p-hydroxy-MP and p-hydroxy-Ph dosed orally to rat were examined.2. Metabolites in the anaerobic incubation of N-hydroxy-MP and N-hydroxy-Ph were MP and Ph, and Ph, respectively. No metabolites were detected in the incubation of MP, Ph, p-hydroxy-MP and p-hydroxy-Ph.3. p-Hydroxy-MP and p-hydroxy-Ph (major), and MP and Ph (minor) were detected when bile from rats given MP was incubated with intestinal contents.4. Unchanged p-hydroxy-MP, and conjugates of p-hydro...

  • metabolism of Mephentermine in male guinea pigs and male mice
    Xenobiotica, 1991
    Co-Authors: Masaaki Mori, M Kobayashi, K Nakafuku, Y Yumoto, T Miyahara, H Kozuka
    Abstract:

    1. Urinary metabolites of Mephentermine (MP), after i.p. administration of MP to male Hartley guinea pigs and mice, were identified by g.l.c.-electron impact (El) mass spectrometry. Excretion of urinary radioactivity, and metabolites of 3H-MP, after i.p. administration, were determined by preparative t.l.c.-liquid scintillation counting.2. About 27% of the radioactivity administered was excreted in the 24 h urine of guinea pigs, and 36% dose was excreted in 5 days. In mice, about 47% of the radioactivity was excreted in the 24 h urine, and 52% in 5 days.3. Excretion rates of metabolites detected in the 24 h urine of guinea pigs were phentermine (Ph, 7.8%), a conjugate of N-hydroxyphentermine (N-hydroxy-Ph, 3.6%), p-hydroxyphentermine (p-hydroxy-Ph, 1.0%) and its conjugate (2.9%), and other metabolites (conjugates of MP and Ph, N-hydroxyMephentermine (N-hydroxy-MP) and its conjugate, p-hydroxyMephentermine (p-hydroxy-MP) and its conjugate, and N-hydroxy-Ph; <1.0%). The rates of excretion for mice were Ph (...

  • isolation of urinary p hydroxylated metabolites of Mephentermine and phentermine in male wistar rats
    Xenobiotica, 1990
    Co-Authors: Masaaki Mori, N Uyyu, K Sakai, Masami Inoue, T Miyahara, Hiroshi Kozuka
    Abstract:

    1. p-HydroxyMephentermine (p-hydroxy-MP) and p-hydroxyphentermine (p-hydroxy-Ph) were isolated as hydrochlorides from urine of male Wistar rats repeatedly dosed with Mephentermine (MP). In addition, p-hydroxy-Ph was isolated as the hydrochloride from urine of the rats dosed with phentermine (Ph).2. These results substantiate previous indications that p-hydroxylation of MP and Ph was a primary metabolic reaction in the rat.

Asha Tyagi - One of the best experts on this subject based on the ideXlab platform.

  • comparison of phenylephrine hydrochloride and Mephentermine sulphate for prevention of post spinal hypotension
    Anaesthesia, 2010
    Co-Authors: Medha Mohta, D Agarwal, A K Sethi, Sai S Janani, Asha Tyagi
    Abstract:

    Summary This study compared the effects of intravenous infusions of phenylephrine and Mephentermine on the prevention of maternal hypotension and neonatal outcome in patients receiving spinal anaesthesia for caesarean section. Sixty ASA 1-2 patients with term, uncomplicated singleton pregnancy undergoing caesarean section under spinal anaesthesia were randomly divided into two groups of 30 each, to receive a prophylactic intravenous infusion of either phenylephrine or Mephentermine. The incidence of hypotension was statistically similar in the two groups. However, in patients receiving phenylephrine, 7 (23%) developed bradycardia and 6 (20%), reactive hypertension. Neonatal outcome, in terms of Apgar scores and umbilical artery pH, was similar in both the groups. To conclude, phenylephrine and Mephentermine infusions are equally effective in preventing post spinal hypotension in patients undergoing caesarean section and are associated with a similar neonatal outcome.

  • potency of Mephentermine for prevention of post spinal hypotension
    Anaesthesia and Intensive Care, 2009
    Co-Authors: Medha Mohta, D Agarwal, L K Gupta, A K Sethi, Asha Tyagi
    Abstract:

    This study was designed to determine the minimum effective dose (ED 50 of Mephentermine for prevention of post-spinal hypotension in women undergoing elective caesarean section. Dixon's up-down method of sequential allocation was used to determine the patient's dose of vasopressor drug. In our previous study, Mephentermine appeared to be much more potent than ephedrine, so the present study was conducted using a lower initial dose and smaller dose interval for this vasopressor. Following administration of spinal anaesthesia, a prophylactic infusion of Mephentermine was started with 5 mg infused over a period of 30 minutes as the initial dose and a dose interval of 1 mg. The ED 50 of Mephentermine of 3.7 mg (95% confidence interval 2.4 to 5.7 mg) was much less than that of ephedrine, as calculated in our previous study using the same methodology. Using these values gives a potency ratio of ephedrine to Mephentermine of 1:6.8 (95% confidence interval 6.0 to 7.5).

  • comparison of potency of ephedrine and Mephentermine for prevention of post spinal hypotension in caesarean section
    Anaesthesia and Intensive Care, 2008
    Co-Authors: Medha Mohta, D Agarwal, L K Gupta, Asha Tyagi, A Gupta, A K Sethi
    Abstract:

    The dosages and potency of intravenous Mephentermine for prevention of post-spinal hypotension are not available in English literature. This study was designed to determine the minimum effective dose (ED 50 ) of Mephentermine and to compare its potency with that of ephedrine for prevention of post-spinal hypotension in parturients undergoing caesarean section. Dixon's up-down method of sequential allocation was used for vasopressor doses. Following administration of spinal anaesthesia, patients received a prophylactic infusion with 50 mg infused over a period of 30 minutes as the initial dose and dose intervals of 5 mg, of either ephedrine or Mephentermine. The ED 50 of ephedrine was 25.0 mg (95% CI 15.5 to 40.4 mg). For Mephentermine, the up-down method was abandoned due to the success of the minimum dose possible but the ED 50 appeared to be less than 5 mg. In conclusion, the minimum effective dose of Mephentermine is much less than that of ephedrine for prevention of post-spinal hypotension. Another trial with a lower starting dose and smaller dose interval of Mephentermine is required to determine the potency ratio of Mephentermine and ephedrine.

  • randomised trial of intravenous infusion of ephedrine or Mephentermine for management of hypotension during spinal anaesthesia for caesarean section
    Anaesthesia, 2005
    Co-Authors: A. Kansal, Medha Mohta, Asha Tyagi, A K Sethi, P. Kumar
    Abstract:

    Summary This study compared the effects of intravenous infusions of ephedrine and Mephentermine for maintenance of maternal arterial pressure and neonatal outcome in pregnant women receiving subarachnoid block for lower segment Caesarean section. Sixty patients who developed hypotension following subarachnoid block for Caesarean section were randomly divided into two groups of 30 each to receive an intravenous infusion of ephedrine or Mephentermine. Hypotension was defined as a decrease in systolic blood pressure of ≥ 20% from the baseline value or an absolute value of <100 mmHg, whichever was higher. The vasopressor infusion was titrated to maintain systolic blood pressure between ‘hypotension’ and baseline values. Baseline haemodynamic parameters, haemodynamic changes subsequent to the start of vasopressor infusion, duration of hypotension and amount of vasopressor required were statistically similar for both groups. Neonatal APGAR scores and acid-base profiles were also comparable. To conclude, Mephentermine can be used as safely and effectively as ephedrine for the management of hypotension during spinal anaesthesia in patients undergoing elective Caesarean section.

  • Randomised trial of intravenous infusion of ephedrine or Mephentermine for management of hypotension during spinal anaesthesia for Caesarean section.
    Anaesthesia, 2004
    Co-Authors: A. Kansal, Medha Mohta, Asha Tyagi, A K Sethi, P. Kumar
    Abstract:

    Summary This study compared the effects of intravenous infusions of ephedrine and Mephentermine for maintenance of maternal arterial pressure and neonatal outcome in pregnant women receiving subarachnoid block for lower segment Caesarean section. Sixty patients who developed hypotension following subarachnoid block for Caesarean section were randomly divided into two groups of 30 each to receive an intravenous infusion of ephedrine or Mephentermine. Hypotension was defined as a decrease in systolic blood pressure of ≥ 20% from the baseline value or an absolute value of

T Miyahara - One of the best experts on this subject based on the ideXlab platform.

  • intestinal metabolism of Mephentermine and its biliary metabolites in male wistar rats
    Xenobiotica, 1992
    Co-Authors: Masaaki Mori, T Miyahara, M Kobayashi, Hiromi Uemura, Hiroshi Kozuka
    Abstract:

    1. Intestinal metabolites produced in the incubation (0–24 h) of Mephentermine (MP), phentermine (Ph), N-hydroxyMephentermine (N-hydroxy-MP), N-hydroxyphentermine (N-hydroxy-Ph), p-hydroxyMephentermine (p-hydroxy-MP) and p-hydroxyphentermine (p-hydroxy-Ph) with male Wistar rat intestinal contents under N2 were examined by g.l.c. and g.l.c.-electron impact (EI) mass spectrometry. Metabolites produced in the anaerobic incubation of bile from rats given MP, with the intestinal contents were also examined. In addition, urinary and biliary metabolites of p-hydroxy-MP and p-hydroxy-Ph dosed orally to rat were examined.2. Metabolites in the anaerobic incubation of N-hydroxy-MP and N-hydroxy-Ph were MP and Ph, and Ph, respectively. No metabolites were detected in the incubation of MP, Ph, p-hydroxy-MP and p-hydroxy-Ph.3. p-Hydroxy-MP and p-hydroxy-Ph (major), and MP and Ph (minor) were detected when bile from rats given MP was incubated with intestinal contents.4. Unchanged p-hydroxy-MP, and conjugates of p-hydro...

  • isolation of urinary p hydroxylated metabolites of Mephentermine and phentermine in male wistar rats
    Xenobiotica, 1990
    Co-Authors: Masaaki Mori, N Uyyu, K Sakai, Masami Inoue, T Miyahara, Hiroshi Kozuka
    Abstract:

    1. p-HydroxyMephentermine (p-hydroxy-MP) and p-hydroxyphentermine (p-hydroxy-Ph) were isolated as hydrochlorides from urine of male Wistar rats repeatedly dosed with Mephentermine (MP). In addition, p-hydroxy-Ph was isolated as the hydrochloride from urine of the rats dosed with phentermine (Ph).2. These results substantiate previous indications that p-hydroxylation of MP and Ph was a primary metabolic reaction in the rat.