Sympathomimetics pharmacokinetics

Pharmacology Amphetamines are sympathomimetic amines with CNS stimulant activity. CNS effects are mediated by release of norepinephrine from central noradrenergic neurons. Peripheral activities include elevation of systolic and diastolic blood pressures and weak bronchodilator and respiratory stimulant action. Pharmacokinetics ... 

Mechanism of Action A sympathomimetic amine that stimulates the release of norepinephrine and dopamine. Therapeutic Effect Decreases appetite. Pharmacokinetics Rapidly absorbed from the gastrointestinal (GI) tract. Widely distributed. Metabolized in liverto active metabolite and undergoes extensive first-pass metabolism. Excreted in urine. Unknown if removed by hemodialysis. Half-life 4-6 hr. 

Mecfianism of Action A phenylalkylamine sympathomimetic with activity similar to amphetamines that stimulates the central nervous system (CNS) and elevates blood pressure (BP) most likely mediated via norepinephrine and dopamine metabolism. Causes stimulation of the hypothalamus. Therapeutic Effect Decreases appetite. Pharmacokinetics The pharmacokinetics of phendimetrazine tartrate has not been well established. Metabolized to active metabolite, phendimetrazine. Excreted in urine. Half-life 2-4 hr. 

Mechanism of Action A sympathomimetic, adrenergic agonist, t hat st i mulates betaj-adrenergic receptors in the lungs, resulting in relaxation of bronchial smooth muscle. Therapeutic Effect Relieves bronchospasm, reduces airway resistance. Pharmacokinetics Absorbed from bronchi following inhalaf ion. Metabolized in liver. Primarily excreted in urine. Unknown if removed by hemodialysis. Half-life 2-3 hr. 

Mechanism of Action A sympathomimetic that directly acts on alpha-adrenergic receptors in arterioles of the nasal mucosa to produce vasoconstriction resulting in decreased blood flow. Therapeutic Effect Decreased nasal congestion. Pharmacokinetics Onset of acf ion occurs wif hin 5-10 minuf es for a duration of action of 5-6 hours. Well absorbed fhrough nasal mucosa. May also be systemically absorbed from bofh nasal mucosa and gasfroinfesfinal (GI) fracf. Half-life Unknown. 

All the clinically available (J-blockers are competitive antagonists. Nonselective [3-blockers act at both (3 and (32 receptors, whereas car-dioselective ( -antagonists primarily block 3i receptors. These drugs also differ in intrinsic sympathomimetic activity, in central nervous system (CNS) effects, and in pharmacokinetics (Figure 7.5). Although all (3-blockers lower blood pressure in hypertension, they do not induce postural hypotension because the a-adrenoceptors remain functional therefore, normal sympathetic control of the vasculature is maintained. P-blockers are also effective in treating angina, cardiac arrhythmias,... 

Tabla 9-3. Pharmacokinetics and ciinicai appiications of some sympathomimetics. 

B. Pharmacokinetics Many shorter-acting local anesthetics are readily absorbed into the blood from the injection site after administration. The duration of local action is therefore limited unless blood flow to the area is reduced. This can be accomplished by administration of a vasoconstrictor (usually an a agonist sympathomimetic) with the local anesthetic agent. Cocaine is an important exception to this rale since it has intrinsic sympathomimetic action (because it in-... 

Table 13.6. Pharmacologic Effects and Pharmacokinetic Properties of Sympathomimetic Bronchodiiators Sympathomimetic ...

Kaddoumi, A. Kubota, A. Nakashima, M.N. Takahashi, M. Nakashima, K. High performance liquid chromatography with UV detection for the simultaneous determination of sympathomimetic amines using 4-(4,5-diphenyl-lH-imidazole-2-yl)benzoyl chloride as a label, Biomed.Chromatogr., 2001, 15, 379-388. [human rat plasma derivatization LOD 50-100 nM ephedrine norephedrine 2-phenylethylamine fenfluramine phentermine cyclohexylamine fluoxetine is internal standard pharmacokinetics]... 

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