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He E. Kang - One of the best experts on this subject based on the ideXlab platform.
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Interaction between udenafil and tamsulosin in rats: Non-Competitive Inhibition of tamsulosin metabolism by udenafil via hepatic CYP3A1/2
British Journal of Pharmacology, 2009Co-Authors: He E. KangAbstract:Background and purpose: Orthostatic hypotension has been observed when PDE 5 (cGMP-specific phosphodiesterase type 5) inhibitors are co-administered with α-adrenoceptor antagonists. Here we assessed the pharmacokinetic and haemodynamic interactions between udenafil and tamsulosin in rats, as both drugs are metabolized via rat hepatic cytochrome P450 3A1/2. Experimental approach: Interactions between the two drugs were evaluated in rats after simultaneous 1 or 15 min i.v. infusion or after p.o. administration of udenafil (30 mg·kg−1) and/or tamsulosin (1 mg·kg−1). In vitro metabolism of tamsulosin with udenafil was measured to obtain the Inhibition constant (Ki) and [I]/Ki ratio of udenafil. Key results: The total area under the plasma concentration–time curve from time zero to time infinity (AUC)s (or AUC0–4h) of tamsulosin were significantly greater after 15 min of i.v. infusion or after oral administration with udenafil, compared with tamsulosin alone. The hepatic first-pass metabolism of tamsulosin was inhibited by udenafil, and the Inhibition in vitro was in a Non-Competitive mode. The arterial systolic blood pressure was significantly lower at 5, 10 and 60 min after oral co-administration of the drugs. Conclusions and implications: The significantly greater AUC of tamsulosin after i.v. and p.o. administration of both drugs may be attributable to Non-Competitive Inhibition of cytochrome P450 3A1/2-mediated hepatic tamsulosin metabolism by udenafil. The Inhibition was also observed in human liver S9 fractions, suggesting that a reassessment of the oral dosage of tamsulosin is necessary when udenafil and tamsulosin are co-administered to patients with benign prostatic hyperplasia.
Dayashankar Singh - One of the best experts on this subject based on the ideXlab platform.
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enzyme Inhibition by molluscicidal component of areca catechu and carica papaya in the nervous tissue of vector snail lymnaea acuminata
Pesticide Biochemistry and Physiology, 2008Co-Authors: Preetee Jaiswal, Vinay Kumar Singh, Dayashankar SinghAbstract:Abstract In the present study toxic effects of active molluscicidal component of Areca catechu and Carica papaya was studied on certain enzymes in the nervous tissue of freshwater snail Lymnaea acuminata. In in vivo and in vitro exposure of arecoline (active component of Areca catechu seed) and papain (C. papaya latex and seed) significantly inhibited the acetylcholinesterase (AChE), acid and alkaline phosphatase (ACP/ALP) activity in the nervous tissue of L. acuminata. The Inhibition kinetics of these enzymes indicate that arecoline and papain caused competitive and uncompetitive Inhibition of AChE, respectively, whereas arecoline caused competitive–Non-Competitive Inhibition of ACP/ALP and papain caused Non-Competitive Inhibition of ACP/ALP. Thus the Inhibition of AChE, ACP and ALP by arecoline and papain in the nervous tissue of L. acuminata may be the cause of molluscicidal activity of A. catechu and C. papaya, respectively.
Dinesh Kumar Singh - One of the best experts on this subject based on the ideXlab platform.
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Inhibition kinetics of certain enzymes in the nervous tissue of vector snail Lymnaea acuminata by active molluscicidal components of Sapindus mukorossi and Terminalia chebula.
Chemosphere, 2011Co-Authors: Aparna Upadhyay, Dinesh Kumar SinghAbstract:Effect of active molluscicidal components of Sapindus mukorossi and Terminalia chebula on the acetylcholinesterase (AChE), acid and alkaline phosphatase (ACP/ALP) activity in the nervous tissue of freshwater snail Lymnaea acuminata were studied. In vivo and in vitro exposure of saponin (active component of S. mukorossi pericarp) and tannic acid (active component of T. chebula) significantly inhibited the AChE, ACP and ALP activity in the nervous tissue of L. acuminata. The Inhibition kinetics of these enzymes indicate that saponin and tannic acid caused competitive and competitive-Non-Competitive Inhibition of AChE, respectively. Saponin also caused competitive and competitive-Non-Competitive Inhibition of ACP and ALP, respectively, whereas tannic acid caused competitive-Non-Competitive Inhibition of ACP and ALP. Thus the Inhibition of AChE, ACP and ALP by saponin and tannic acid in the nervous tissue of L. acuminata may be the cause of molluscicidal activity of S. mukorossi and T. chebula.
Warren D. Blackburn - One of the best experts on this subject based on the ideXlab platform.
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Effects of tenidap on superoxide-generating enzymes: Non-Competitive Inhibition of xanthine oxidase
Biochemical pharmacology, 1995Co-Authors: W. Winn Chatham, Joseph E. Baggott, Leland D. Loose, Warren D. BlackburnAbstract:Abstract The anti-rheumatic drug tenidap has been shown previously to attenuate superoxide production by activated neutrophils. Given the importance of leukocyte as well as endothelial cell derived superoxide in mediating inflammatory responses, the effects of tenidap on mammalian enzymes capable of generating superoxide were determined. Tenidap had no effect on the generation of superoxide by NADPH oxidase reconstituted from fractionated neutrophil lysates. However, significant Inhibition of superoxide production by mixtures of hypoxanthine and xanthine oxidase was observed in the presence of 3–30 μg/mL tenidap. The kinetics of xanthine oxidase Inhibition by tenidap were Non-Competitive; the Ki of tenidap for xanthine oxidase was 11 μg/mL (34 μM). No Inhibition of xanthine oxidase was observed in the presence of other known inhibitors of cyclooxygenase. Inhibition of xanthine oxidase may be a heretofore unrecognized mechanism of the antirheumatic effects of tenidap.
Preetee Jaiswal - One of the best experts on this subject based on the ideXlab platform.
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enzyme Inhibition by molluscicidal component of areca catechu and carica papaya in the nervous tissue of vector snail lymnaea acuminata
Pesticide Biochemistry and Physiology, 2008Co-Authors: Preetee Jaiswal, Vinay Kumar Singh, Dayashankar SinghAbstract:Abstract In the present study toxic effects of active molluscicidal component of Areca catechu and Carica papaya was studied on certain enzymes in the nervous tissue of freshwater snail Lymnaea acuminata. In in vivo and in vitro exposure of arecoline (active component of Areca catechu seed) and papain (C. papaya latex and seed) significantly inhibited the acetylcholinesterase (AChE), acid and alkaline phosphatase (ACP/ALP) activity in the nervous tissue of L. acuminata. The Inhibition kinetics of these enzymes indicate that arecoline and papain caused competitive and uncompetitive Inhibition of AChE, respectively, whereas arecoline caused competitive–Non-Competitive Inhibition of ACP/ALP and papain caused Non-Competitive Inhibition of ACP/ALP. Thus the Inhibition of AChE, ACP and ALP by arecoline and papain in the nervous tissue of L. acuminata may be the cause of molluscicidal activity of A. catechu and C. papaya, respectively.