Hypotensive drug 2 receptor agonist

The hypotensive effects of most antihypertensive dru are increased when administered with diuretics and other antihypertensives. Many dnigp can interact with the antihypertensive drugs and decrease their effectiveness (eg, antidepressants, monoamine oxidase inhibitors, antihistamines, and sympathomimetic bronchodilators). When the ACE inhibitors are administered with the NSAIDs, their antihypertensive effect may be decreased. Absorption of the ACE inhibitors may be decreased when administered with the antacids. Administration of potassium-sparing diuretics or potassium supplements concurrently with the ACE inhibitors may cause hyperkalemia. When the angiotensin II receptor agonists are administered with... 

Salzmann R, Fozard JR (1994) The Haemodynamic basis of the hypotensive response to the putative adenosine A3 receptor agonist, N6-2-(4-amino-phenyl)ethyl adenosine (APNEA) in the rat. Drug Dev Res 31 270... 

Source Reprinted from Takagi, Y., Nakajima, /., Shimazaki, A., et al. Pharmacological characteristics of AFP-168 (tafluprost), a new prostanoid FP receptor agonist, as an ocular hypotensive drug. Exp. Eye Res., (2004) 78, 767-776, with permission from Elsevier)... 

Direct a agonists such as noradrenaline itself and phenylephrine are useful for treating hypotension. Drugs acting at ai receptors are used as nasal decongestants through their action in promoting vasoconstriction of the blood vessels in mucous membranes. 

Xylometazoline and oxymetazoline are direct-acting agonists. These drugs have been used as topical decongestants because of their ability to promote constriction of the nasal mucosa. When taken in large doses, oxymetazoline may cause hypotension, presumably because of a central clonidine-like effect (see Chapter 11). Oxymetazoline has significant affinity fortx receptors. 

Increasing peripheral resistance is one of the strategies to treat chronic orthostatic hypotension, and drugs activating receptors can be used for this purpose. Midodrine, an orally active 04 agonist, is frequently used for this indication. Other sympathomimetics, such as oral ephedrine or phenylephrine, can be tried. 

After intravenous injection, clonidine produces a brief rise in blood pressure followed by more prolonged hypotension. The pressor response is due to direct stimulation of partial agonist at a receptors because it also inhibits pressor effects of other agonists. 

Oxymetazoline (Afrin, Visine, many others). This drug is used in nose drops and nasal sprays to decrease nasal congestion through alpha- 1-mediated vasoconstriction. Higher or systemic doses may also cause hypotension, presumably because central nervous system (CNS) alpha-2 receptors are stimulated in a manner similar to clonidine (see Alpha-2-Selective Agonists ). Oxymetazoline can also be administered as eye drops to decrease redness and minor eye irritation. 

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