Nitroglycerin Nitroprusside

Noninterfering alfentanil, aprotinin, atropine, bupivacaine, chlorpromazine, dalteparin, dexamethasone, diazepam, dopamine, droperidol, etomidate, fentanyl, furosemide, gallamine, haloperidol, midazolam, morphine, neostigmine, nitroglycerin, nitroprusside, oxytocin, pancuronium, pentobarbital, phenylephrine, phenytoin, pipecuronium, piperacillin, promethazine, propofol, ranitidine, succinylcholine, sufentanil, terbutaline, thiopental, vecuronium, verapamil... 

Cyclic GMP is made from GTP by the enzyme gua-nylyl cyclase, which exists in soluble and membrane-bound forms. Each of these isozymes has unique physiologic properties. The atriopeptins, a family of peptides produced in cardiac atrial tissues, cause natriuresis, diuresis, vasodilation, and inhibition of aldosterone secretion. These peptides (eg, atrial natriuretic factor) bind to and activate the membrane-bound form of guanylyl cyclase. This results in an increase of cGMP by as much as 50-fold in some cases, and this is thought to mediate the effects mentioned above. Other evidence links cGMP to vasodilation. A series of compounds, including nitroprusside, nitroglycerin, nitric oxide, sodium nitrite, and sodium azide, all cause smooth muscle re-... 

FIGURE 8-2. General treatment algorithm for acute decompensated heart failure (ADHF) based on clinical presentation. IV vasodilators that may be used include nitroglycerin, nesiritide, or nitroprusside. Metolazone or spironolactone may be added if the patient fails to respond to loop diuretics and a second diuretic is required. IV inotropes that may be used include dobutamine or milrinone. (D/C, discontinue HF, heart failure SBP, systolic blood pressure.) (Reprinted and adapted from J Cardiac Fail, Vol 12, pages el-el 22, copyright 2006, with permission from Elsevier.)... 

Tolerance to nitrates is defined as the reduction in hemodynamic effect or the requirement for higher doses to achieve a persistent effect with continuous use in the face of constant plasma concentrations [15]. Nitrate tolerance was first described for nitroglycerin in 1888 [36] it occurs with all organic nitrates, albeit to different extents. For reasons that are not understood, PETN appears to be the least susceptible to the development of tolerance. No, or much less, tolerance is observed with nitrite esters, such as amyl nitrite [37], molsidomine, and sodium nitroprusside. Earlier investigations suggested that a depletion of intracellular thiols is involved in tolerance development [17], but this has not been substantiated in later studies [38, 39]. As with organic nitrate bioactivation, the precise mechanism(s) involved in nitrate tolerance remain(s) unknown, but it is likely to be complex and multifactorial. Two principal... 

Drugs for the control of hypertensive crises include nifedipine (capsule, to be chewed and swallowed), nitroglycerin (sublingually), clonidine (p.o. or i.v., p. 96), dihydralazine (i.v.), diazoxide (i.v.), fenoldopam (by infusion, p. 114) and sodium nitroprusside (p. 120, by infusion). The nonselective a-blocker phentolamine (p. 90) is indicated only in pheochromocytoma... 

Sotalol Nitroglycerin Amiodarone Beclomethasone Sodium nitroprusside... 

Since these nitrate-based compounds cause blood vessels to dilate, they are called nitrovasodilators. Nitrovasodilators have clinical utility in the treatment of angina and in the treatment of malignant hypertension (high blood pressure that is severely out of control). Some of the available nitrovasodilator products include amyl nitrite (4.228), nitroglycerin (4.229), isosorbide dinitrate (4.230), erythrityl tetranitrate (4.231), pentaery-thritol tetranitrate (4.232) and sodium nitroprusside (4.233). 

Figure 8.2 Proposed mode of action of the organic nitrates, nitroglycerin and nitroprusside. Note that nitroprusside acts as a direct donor of nitric oxide (NO), whereas the nitrates require the presence of nitrosothiols to produce NO.

Calcium channel blockers with vasodilator effects, such as nifedipine, nicardipine, and nimodipine, will potentiate the effect of vasodilator effects of, e.g. halothane or isoflurane, potentiating any hypotension. This is especially obvious in hypertensive patients and when combined with similarly acting agents, such as sodium nitroprusside or nitroglycerin. Similarly, they also enhance the tendency of volatile anaesthetics to reduce hypoxic pulmonary vasoconstriction, which might exacerbate ventilation/perfusion mismatching during anaesthesia. 

Aronson S et al The ECLIPSE trials Comparative studies of clevidipine to nitroglycerin, sodium nitroprusside, and nicardipine for acute hypertension in cardiac surgery patients. Anesth Alang 2008 107 1110. [PMID 18806012]... 

---