Catecholamines pharmacokinetics

Pharmacology Lithium alters sodium transport in nerve and muscle cells, and effects a shift toward intraneuronal catecholamine metabolism. The specific mechanism in mania is unknown, but it affects neurotransmitters associated with affective disorders. Its antimanic effects may be the result of increases in norepinephrine reuptake and increased serotonin receptor sensitivity. Pharmacokinetics ... 

The pharmacokinetics of morphine have been studied,201-203 as has its receptor binding,204-206 and its effects on hypothermia,207 on calcium uptake by synaptosomes208 and lysed synaptosomes,209 on metabolism of catecholamine in brain,210 on levels of corticosteroids and growth hormone in plasma,211 on leuteinising hormone,212 follicle-stimulating hormone,212 and prolactin,212-215 on neuroendocrine function,216 on brain function and biochemistry,217-226 on behaviour,227-240 on the gastrointestinal tract241 and on the cardiovascular... 

Pharmacokinetics Epinephrine has a rapid onset but brief duration of action. In emergency situations epinephrine is given intravenously for the most rapid onset of action it may also be given subcutaneously, by endotracheal tube, by inhalation, or topically to the eye. Oral administration is ineffective, since epinephrine and the other catecholamines are inactivated by intestinal enzymes. Only metabolites are excreted in the urine. 

In addition to pharmacokinetic drug-drug interactions, pharmacodynamic effects have been reported as well. Halothane increases the susceptibility to ventricular arrhythmias under theophylline therapy as a result of increased sensitivity of the myocardium to endogenous catecholamine release by theophylUne. Ketamine lowers the theophyUine seizure threshold. Benzodiazepines Uke midazolam, diazepam, lorazepam, and Uurazepam increase the central nervous system concentration of adenosine, a potent central nervous system depressant. As theophyUine also blocks adenosine receptors, it counteracts benzodiazepine-induced sedation, resulting in increased dosage requirements for these compounds. ... 

Tranylcypromine is a chiral monoamine oxidase inhibitor used in the treatment of depression. The drug is similar to mefloquine in that it is contains a diastereomeric structure but is only administered as the 50 50 combination of the (- -)-lS,2R and (—)-lR,2S species. The enantiomers possess differences in their pharmacological properties in that (-I-) tranylcypromine is much more effective than its antipode in MAO inhibition, but the (—) enantiomer causes greater diminution of catecholamine reuptake and release than (-I-) enantiomer [147]. With respect to its pharmacokinetics (Table 1), the (-I-) enantiomer seemed to be cleared via the oral route 4 to 8 times more rapidly than antipode based on significantly... 

In one study, healthy subjects were given desipramine 25 mg three times daily for 3 days then 50 mg three times daily for 10 days. For the last 5 days they were also given levodopa/carbidopa 100/25 mg three times daily and either a placebo or tolcapone 200 mg three times daily. The addition of tolcapone to combined treatment with levodopa/carbidopa and desipramine did not lead to any changes in haemodynamics or catecholamine levels, nor to any changes in desipramine pharmacokinetics. ... 

Catechol bioisosteres are often utilized to overcome pharmacokinetic and toxicological issues linked to this moiety. SuccessfiJ examples of bioisosteric replacement of catechols can be found in catecholamines. Benzimidazole analogues of the adrenergic agonists norepinephrine and isoproterenol (Figure 2.10) were... 

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