Catecholamines pharmacological properties

The neuronal membrane norepinephrine transporter (NET), the dopamine transporter (DAT) and the vesicular membrane transporter (VMAT-2), which is the same in all catecholamine-containing neurons, have similar numbers of predicted transmembrane segments. They have different numbers of amino acids, pharmacological properties and chromosomal localizations. 

When fluid resuscitation is insufficient to maintain tissue perfusion, the use of inotropes and vasoactive drugs is necessary. Selection and dosage are based on the pharmacologic properties of various catecholamines and how they influence hemodynamic parameters (Table 45-5). 

Isoflurane (Forane) is a structural isomer of enflurane and produces similar pharmacological properties some analgesia, some neuromuscular blockade, and depressed respiration. In contrast, however, isoflurane is considered a particularly safe anesthetic in patients with ischemic heart disease, since cardiac output is maintained, the coronary arteries are dilated, and the myocardium does not appear to be sensitized to the effects of catecholamines. Also, blood pressure falls as a result of vasodilation, which preserves tissue blood flow. Isoflurane causes transient and mUd tachycardia by direct sympathetic stimulation this is particularly important in the management of patients with myocardial ischemia. 

EDS is usually treated using amphetamine-like CNS stimulants or modaflnil, a novel wake-promoting compound unrelated to amphetamines. The most commonly used amphetamine-like compounds aremethamphetamine, D-amphetamine, methylpheni-date, pemoline, and mazindol. The most important pharmacological property of these compounds is to release catecholamines, i.e., dopamine and norepinephrine. Amphetamine-like compounds also share the property of blocking the reuptake and the degradation of these monoamines (monoamine oxidase inhibition at high doses). All these properties presynaptically enhance dopamine transmission, which are likely to contribute to the EEG arousal effects of amphetamines. 

I. Pharmacology. Isoproterenol is a catecholamine-like drug that stimulates beta-adrenergic receptors (beta-1 and -2). Pharmacologic properties include positive inotropic and chronotropic cardiac effects, periphery vasodilation, and bron-chodilation. Isoproterenol is not absorbed orally and shows variable and erratic absorption from sublingual and rectal sites. The effects of the drug are rapidly terminated by tissue uptake and metabolism effects persist only a few minutes after intravenous injection. 

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... 

The pharmacological properties of the catecholamines (3-hydroxytyr-amine, /-noradrenaline, adrenaline) are of a sympathomimetic nature. 3-Hydroxy tyramine increases the blood pressure in animals and in man. 60, 63. 212, 299, 823, 998,1020, 1022,1033-43) rcspective potcncy of adrenaline, hydroxytyramine, and tyramine on the blood... 

I. Pharmacology. Epinephrine is an endogenous catecholamine with alpha- and beta-adrenergic agonist properties, used primarily in emergency situations to treat anaphylaxis or cardiac arrest. Beneficial effects include inhibition of histamine release from mast cells and basophils, bronchodilation, positive inotropic effects, and peripheral vasoconstriction. Epinephrine is not active after oral administration. Subcutaneous injection produces effects within 5-10 minutes, with peak effects at 20 minutes. Intravenous or inhalational administration produces much more rapid onset. Epinephrine is rapidly inactivated in the body, with an elimination half-life of 2 minutes. 

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