Sympathomimetics direct

CENTRALLY ACTING ANTI HYPERTENSIVES SYMPATHOMIMETICS-DIRECT Risk of t BP when donidine is given with epinephrine or norepinephrine Additive effect donidine use associated with t circulating catecholamines Monitor BP at least weekly until stable... 

VASODILATOR ANTIHYPERTENSIVES SYMPATHOMIMETICS-DIRECT Cases of t tachycardia when epinephrine is given for perioperative i BP in patients on hydralazine Additive effect Avoid co-administration... 

Direct-acting Sympathomimetics Directly stimulate receptors... 

Sympathomimetics (directly acting) Combining MAOis with agents such as epinephrine or norepinephrine is relatively safe since MAOis cause them to accumulate in the nerve terminal (thus, they do not directly act on postsynaptic receptors). 

Direct-acting sympathomimetics—directly stimulate receptors. 

COMT inhibitors may inhibit the normal metabolism of ephedrine (and the catecholamines it releases at adrenergic nerve endings), which could result in a marked exaggeration of its normal effects. See also COMT inhibitors -I- Sympathomimetics Directly-acting , above. 

Note that drugs with directly-acting sympathomimetic effects (of which beta agonists are an example) do not normally interact to cause hypertension with MAOIs, see sympathomimetics directly-acting , (below). However, phenylephrine (which has some indirect actions, see sympathomimetics phenylephrine , (p.l 148)) may have contributed to the reaction between toloxatone and terbutaline, and the fact that terbutaline seems to have been given orally would also have eontributed. The hypomania reaction is not understood. 

Increased pharmacologic effects of direct-acting sympathomimetics decreased effects of indirect-acting sympathomimetics Increased therapeutic and possibly toxic effects of both drugs CNS stimulation tachycardia... 

In rats, we know that tolerance does not occur to parasympathomimetic effects of LSD at a time when sympathomimetically mediated and behavioral effects show tolerance. Apart from the postreserpine LSD-induced pupillary changes, such differential effects in man are not known. We know also that the bradycardia in unrestrained rats (19) converts readily to a tachycardia, and assertions that LSD elevates blood pressure or pulse in man should be viewed as reactivity rather than a direct effect. 

Predictable interactions occur between the MAOIs and any amine precursors, or directly or indirectly acting sympathomimetic amines (e.g. the amphetamines, phenylephrine and tyramine). Such interactions can cause pronounced hypertension and, in extreme cases, stroke. 

Unlike guanethidine, t-octylguanidine shows little sympathomimetic activity. A direct vasodilatation has been demonstrated, but it is doubtful whether this plays a very important role in the action of this drug. The possibility of a central... 

Isoetharine is a direct-acting sympathomimetic with relatively low selectivity with j32-adrenoreceptors. However, it quickly calms bronchospasms better than more selective bronchodilators. It is used in treating chronic obstructive illnesses of outer respiratory tract. Synonyms of this drug are asthmalitan and bronkosol. 

Terbutaline is a synthetic sympathomimetic amine. It is one of the most selective direct-acting stimulants of )32 dr6noreceptors. It stimulates smooth muscle )32-adrenoreceptors in the bronchi, relaxing them and relatively minutely acting on the — receptors of the heart. 

Metaraminol is a sympathomimetic amine of both direct and indirect action that has hemodynamic characteristics similar to norepinephrine. It has the ability to elevate both systohc and diastolic blood pressure. 

Phentolamine is also a derivative of imidazoline that exhibits a direct a-adrenoblocking, muscle-relaxant effect on smooth muscle as well as cholinomimetic, histamine, and sympathomimetic effects. The chemical variation of its stmcture permits a few of its properties to be more expressed. For example, the aforementioned tolazoline, 2-benzyl-2-imidazoline, a structural analog of phentolamine, has more of an expressed muscle-relaxant effect on smooth muscle than an a-adrenoblocking effect. 

Pharmacology Epinephrine, a direct-acting sympathomimetic agent, acts on and receptors. Topical application, therefore, causes conjunctival decongestion (vasoconstriction), transient mydriasis (pupillary dilation), and reduction in intraocular pressure (lOP). It is believed lOP reduction primarily is caused by reduced aqueous production and increased aqueous outflow. The duration of decrease in lOP is 12 to 24 hours. 

Bromocriptine (Parl el) [Antiparkinsonian Agent/Dopamine Receptor Agonist] Uses Parkin on Dz, hyperprolactinemia, acromegaly, pituitary tumors Action Direct-acting on the striatal dopamine receptors X prolactin secretion Dose Initial, 1.25 mg PO bid titrate to effect, w/ food Caution [B, ] Contra Severe ischemic heart Dz or PVD Disp Tabs, caps SE X BP, Raynaud phenomenon (vasospastic disorder resulting in discoloration of the fmgers/toes), dizziness, N, hallucinations Interactions T Effects W/ erythromycin, fluvoxamine, nefazodone, sympathomimetics, antihypertensives X effects W/ phenothiazines, antipsychotics EMS Monitor BP may cause intolerance to EtOH OD May cause NA, severe hypotension give IV fluids symptomatic and supportive... 

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