Pharmacology
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The present study was designed to investigate the effects of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (atorvastatin, pravastatin, simvastatin) on the pharmacokinetics of losartan and its active metabolite EXP-3174 in rats. Pharmacokinetic parameters of losartan and EXP-3174 in rats were determined after oral and intravenous administration of losartan (9 mg/kg) without and with HMG-CoA reductase inhibitors (1 mg/kg). The effect of HMG-CoA reductase inhibitors on P-gp and cytochrome (CYP) 3A4 activity were also evaluated. ⋯ Consequently, the absolute bioavailability (F) of losartan after oral administration with simvastatin was significantly increased by 59.4% compared to that of control. The metabolite-parent AUC ratio was significantly decreased by 25.7%, suggesting that metabolism of losartan was inhibited by simvastatin. In conclusion, the enhanced bioavailability of losartan might be mainly due to inhibition of P-gp in the small intestine and CYP3A subfamily-mediated metabolism of losartan in the small intestine and/or liver and to reduction of the CL/F of losartan by simvastatin.
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Recently, paeoniflorin (PF) administered systemically was found to have analgesic effects against inflammatory pain and hypersensitivity in a naloxone-reversible manner. In the present study, we adopted intrathecal administration to evaluate whether PF has direct antinociceptive actions at the spinal level. Pain-related behaviors and spinal c-Fos expression were induced by subcutaneous injection of bee venom (BV) into one hind paw of a rat. ⋯ We further evaluated the intrathecal effects of the drug on the BV-induced c-Fos expression. The result showed that intrathecal PF preconditioning was effective to suppress spinal c-Fos expression in both superficial (lamina I-II) and deep (lamina IV-VI) layers of the L(4-5) dorsal spine. This result showed that PF has a direct pharmacological action in the spinal cord dorsal horn via activation of opioid receptors.
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Comparative Study
Effects of hydroxyethyl starch, gelatin and dextran on endothelium-derived relaxation in porcine coronary arteries.
In a pilot study we could show that hydroxyethyl starch (HES) induced a significant reduction of endothelium-dependent relaxation (EDR) and the endothelium-derived hyperpolarizing factor (EDHF). In this follow-up study we investigated whether this effect of HES was dose-dependent and whether it could be replicated with other colloids like dextran (DX) and gelatin (GL). ⋯ For clinically relevant concentrations of HES, DX and GL a significant reduction in both NO-induced and NO-/prostacyclin-independent EDR can be found in epicardial coronary arteries of the pig.
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Comparative Study
Analgesic and antiallodynic effects of antidepressants after infiltration into the rat.
Tricyclic antidepressants (TCA) have potent local anesthetic properties and may produce a long-lasting pain blockade that could be of interest in relieving chronic pain states such as neuropathic pain, but there are only few data comparing their dose-response curves of analgesic activity under the same experimental conditions. This study examines the time course of pain-relieving properties of 7 TCA in heat-induced paw withdrawal after subcutaneous administration. Mixed inhibitors of norepinephrine and serotonin uptake (amitriptyline, nortriptyline, imipramine, desipramine, doxepin) and selective inhibitors of serotonin uptake (fluoxetine and fluvoxamine) were assayed. ⋯ The antiallodynic effect always lasted less long than the analgesic effect. These observations provide support for the potential use of TCA as durable analgesics. Doxepin overall showed the most outstanding results in pain relief.
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Comparative Study
Pharmacokinetic-pharmacodynamic modeling of methylxanthine derivatives in mice challenged with high-dose lipopolysaccharide.
Pentoxifylline and lisofylline are methylxanthine derivatives that exhibit anti-inflammatory activity both in vitro and in vivo. This study was designed to develop a pharmacokinetic-pharmacodynamic (PK/PD) model to describe the inhibitory effect of these compounds on TNF-alpha production in mice challenged with bacterial lipopolysaccharide (LPS). ⋯ It seems that pentoxifylline is more potent than lisofylline in inhibiting TNF-alpha production in vivo. The proposed PK/PD model allowed a better understanding of the pharmacological properties of both methylxanthine derivatives and may be helpful in appropriate dosage selection for further studies.