Adrenoreceptor stimulation

Ritodrine is a selective Sj-adrenoreceptor stimulant, predominantly of the urino-genital system. It is used as a tocolytic agent for problems associated with premature miscarriages, and only in specialized medical facilities. Synonyms of ritodrine are yutopar and pre-par. 

Clinical studies showed that elderly patients are more sensitive to drugs such as sedatives, hypnotics, and analgesics. The most extensive studies show a decrease in responsiveness to /3-adrenoreceptors, stimulants, and blockers. Hypothermia is poorly tolerated by the elderly, as their body temperature regulation is impaired. 

Hall, I.P. and Hill, S.J. (1988). -Adrenoreceptor stimulation inhibits histamine-stimulated inositol phospholipid hydrolysis in bovine tracheal smooth muscle. Br. J. Pharmacol. 95, 1204-1212. 

Psychotomimetic drugs biochemistry and pharmacology. 7. 165 Purine receptors and their pharmacological roles, 18. 292 The Rate of contemporary drug discovery. 8. I Recent /3-adrenoreceptor stimulants. 5. 197... 

Beta2 adrenoreceptor stimulants cause bronchodilation by acting on adrenoreceptors in bronchial smooth muscle. Although they are selective for 2 receptors these drugs do have some affect on cardiac Pi receptors. Cardiac side effects are not usually a problem at therapeutic doses, but could be if a patient decided to increase the dose above that recommended. 

P2 adrenoreceptor stimulants are used as first choice for the rapid relief of an acute asthmatic attack and maintenance treatment of chronic asthma. They are more effective in treatment of the immediate phase reaction than the late phase reaction. P2 adrenoreceptor stimulants are less effective in chronic bronchitis, possibly because in this disease bronchoconstriction is due to reflex stimulation of acetylcholine receptors following stimulation of local irritant receptors in lung tissue. 

Side effects of P2 adrenoreceptor stimulants are rare but include ttemor, nervous tension, headache, peripheral vasodilation, tachycardia (increased heart rate), and hypokalae-mia (low potassium levels) after high doses, and hypersensitivity reactions. 

Antimuscarinic drugs are used to relieve, or at least partially reverse, bronchoconstriction that is refractory to P2 adrenoreceptor stimulants. These drugs work by blocking acetylcholine receptors (the so-called muscarinic receptors) in the bronchioles. This effectively prevents bronchoconstriction in response to parasympathetic stimulation. They may be used in combination with other bronchodilators. Antimuscarinics are of particular use in chronic bronchitis where the airways seem resistant to P2 receptor stimulation and because they also reduce mucus secretion. They are most frequently used as aerosol inhalers and in nebulizers. 

It is closely related structurally to salbutamol, the only difference being that the former has a basic-pyridine nucleus while the latter has a benzene ring (nucleus). It is also a direct-acting sympathomimetic agent having a most prominent P-adrenoreceptor stimulant action, and a selective aetion on P2-receptors. 

The sulfamlde has B-adrenoreceptor stimulant potency intermediate between the ethyl (18) and isopropyl (19) carbani-lates. ... 

PROBLEM 16.67 Metaproterenol (orciprenaline, 1) is a P-adrenoreceptor stimulant used therapeutically as a bron-chodilator. In the synthesis of the hydrobromide salt of racemic 1, outlined below, supply the appropriate reagents. 

BS 110—141, N-amidino-2-(2,6-dichlo-rophenyljacetamide HCl is a guanidine derivative, but its pharmacological action resembles that of clonidine it possesses a central os-adrenoreceptor stimulant activity and causes a centrally induced fall in blood pressure, due probably to lowering of sympathetic activity and reduction of circulatory pressor reflexes. Apparently because of this, postural hypotension seems to be rare. In a series of 15 patients some general side effects were recorded and (surprisingly) the development of a tremor in 5 on a 3—6 mg daily dose (22 =). 

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