Isoproterenol adverse effects

Isoproterenol is given sublingually or by iv. It is metabolized by monoamine oxidase and catechol-0-methyltransferase in brain, Hver, and other adrenergically innervated organs. The pharmacological effects of isoproterenol are transient because of rapid inactivation and elimination. About 60% is excreted unchanged. Adverse effects using isoproterenol therapy include nervousness, hypotension, weakness, dizziness, headache, and tachycardia (86). 

At recommended dosages, adverse effects from inhaled isoproterenol are infrequent and not serious. When excessive dosages are used, tachycardia, dizziness, and nervousness may occur, and some patients may have arrhythmias. 

One of the most important uses of sympathomimetic drugs is in the therapy of bronchial asthma. This use is discussed in Chapter 20. Nonselective drugs (epinephrine), -selective agents (isoproterenol), and B2-selective agents (albuterol, metaproterenol, terbutaline) all are available for this indication. Sympathomimetics other than the 32-selective drugs are now rarely used because they are likely to have more adverse effects than the selective drugs. 

Adverse effects Isoproterenol s adverse effects are similar to those of epinephrine. 

The correct answer = A. Doxazosin is an competitive blocker at the oci receptor and lowers blood pressure. In addition it blocks the smooth muscle of the bladder neck and prostate to improve urine flow. Labetalol and propranolol, while effective for treating the hypertension, are contraindicated in an asthmatic. They would not improve urine flow. Phentolamine has too many adverse effects to be used as an hyper-I tensive agent. Isoproterenol is a p agonist and is not employed as an hypertensive nor would it affect urinary function. 

Tolcapone and entacapone inhibit the enzyme oateohol-O-methyl transferase (COMT), whioh is oonoemed with the metabolism of drugs such as adrenaline (epinephrine) and isoprenaline (isoproterenol). There is therefore a possibility of inoreased serum levels and related adverse effects of these drugs. 

The pressor effects of intravenous infusions of noradrenaline were increased four to eightfold, of adrenaline two to fourfold, and of phenylephrine two to threefold in 4 healthy subjects who had been taking imipramine 75 mg daily for 5 days. There were no noticeable or consistent changes in their response to isoprenaline (isoproterenol). However, in a study of possible adverse interactions between imipramine and isoprenaline, although no abnormalities of heart rhythm were seen, one out of the 4 healthy subjects studied showed potentiation of isoprenaline- induced tachycardia. ... 

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