Sympatholytic drugs

Beta-adrenergic blockers have been used extensively to decrease blood pressure and are a mainstay of antihypertensive therapy in many patients.4,81 Beta blockers exert their primary effect on the heart, where they decrease heart rate and force myocardial contraction. In hypertensive patients, these drugs lower blood pressure by slowing down the heart and reducing cardiac output. This statement, however, is probably an oversimplification of how beta blockers produce an antihypertensive effect. In addition to their direct effect on the myocardium, beta blockers also produce a general decrease in sympathetic tone.19,39 Although their exact effects on sympathetic activity remain to be determined, beta blockers may decrease sympathetic activi- 

Nadolol (Corgard) Oxprenolol (Trasicor) Penbutolol (Levatol) Methyldopa (Aldomet) 

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Sympatholytic drugs are a group of drugs, which decrease the activity of the sympathetic nervous system, mainly by blocking the action of adrenaline and noradrenaline at adrenoceptors. 

Nevertheless, this method was successfully applied by Gulyaeva et al. for the log P and log D determination of 15 P-sympatholytic drugs [56]. Another study by Welerowicz and Buszewski compared the HpophiHcity values of P-blockers obtained with a column made of a monoHthic-silica Cjg with a conventional porous silica particles Cjg as reference material [27]. A modified method was used for evaluating logP with two main differences (i) logfeg was considered rather than retention times, and (ii) benzene and butyl-benzene were used as calibration compounds. 

We will conclude this chapter by referring to a term often used for those symptomatic drugs inhibiting the action of the autonomic nervous system by interfering with the effect of the chemical mediators involved. There are two groups. (1) Para-sympatholytic drugs block the action of acetylcholine. These are included within the wider class of spasmolytics which, as the name suggests, check or eliminate spasms. (2) Sympatholytics inhibit the action of adrenaline, noradrenaline and the sympathetic nervous system. 

There is recent evidence that a third form of interaction is possible. If a receptor system has a basal activity without a receptor-agonist interaction then there exist the possibility of an so-called inverse ag-onism, that is a drug that actually inhibits the basal activity as a result of its binding to the receptor. This phenomenon has been shown for various sympatholytic drugs. 

Class 2 action is sympatholytic. Drugs with this action reduce B-adrenergic activity in the heart. 

Sympatholytics Drugs that inhibit or antagonize function within the sympathetic nervous system. 

Discuss the advantage of the use of sympatholytic drugs that have partial beta activity. 

THERAPEUTIC USES Minoxidil is reserved for the treatment of severe hypertension that responds poorly to other antihypertensive medications, especially in male patients with renal insufficiency. Minoxidil must be given concurrently with a diuretic to avoid fluid retention and with a sympatholytic drug (usually a fi receptor antagonist) to control reflex cardiovascular effects. The drug usually is administered either once or twice a day, but some patients may require more frequent dosing for adequate control of blood pressure. The initial daily dose of minoxidil may be as little as 1.25 mg, which can be increased gradually to 40 mg in one or two daily doses. 

IV. Diagnosis. The findings of hypotension and bradycardia, particularly with sinus arrest or AV block, in the absence of QRS interval prolongation should suggest calcium antagonist intoxication. The differential diagnosis should include beta blockers and other sympatholytic drugs. 

Use in ambidatory patients patients with reduced circidating blood volume, impaired myocardial function or on sympatholytic drugs should be monitored for the possible occmrence of orthostatic hypotension, a frequent complication in single-dose neuraxial morphine analgesia Epidmal morphine should not be given to outpatient singical patients. 

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