Hypotensives

Mention must be made of the u.se of o- or p-hydroxystyryl thiazolo dyes as indicators for protolytic titrations in nonaqueous media (145). and of the hypotensive action of some neotrinuclear thiazolo cyanines in experiments on animals (146). 

Many other bisben2ylisoquinoliae alkaloids, such as tetrandriae (80), from Cjcleapeltata Hook., are also known. Compound (80), for example, although it causes hypotension and hepatotoxicity ia mammals, ia other tests, possessed enough anticancer activity to be considered for preclioical evaluation (55). The arrow poison tubocurare prepared from Chondrendendron spp. also contains the bisben2yhsoquiQoline alkaloid tubocurariae (9). 

The resuspended and formulated Fraction II precipitate normally contains some aggregated IgG and trace substances that can cause hypotensive reactions in patients, such as the enzyme prekail ikrein activator (186). These features restrict this type of product to intramuscular adininistration. Further processing is required if products suitable for intravenous adininistration are required. Processes used for this purpose include treatment at pH 4 with the enzyme pepsin [9001-75-6] being added if necessary (131,184), or further purification by ion-exchange chromatography (44). These and other methods have been fiiUy reviewed (45,185,187,188). Intravenous immunoglobulin products are usually suppHed in the freeze-dried state but a product stable in the solution state is also available (189). 

Dorex is very toxic (see Table 2) and must be handled with extreme care. Because it may produce severe dermatitis on moist skin, it is difficult to use in hot, humid climates inhalation of the dust or spray may irritate the mucous membranes. Whereas symptoms may include a flushed face, tachycardia, headache, vertigo, and hypotension, it does not produce the typical cyanide effect. 

Combined Hj /H2 receptor stimulation by histamine is responsible for vasodilation-related symptoms, such as hypotension, flushing, and headache, as well as for tachycardia stimulated indirecdy through vasodilation and catecholamine secretion. 

Neurotensin. This hormone has been isolated and characterized from acid—acetone extracts of bovine hypothalamus (118) on the basis of its hypotensive activity. Immunoreactive neurotensin is present in mammalian gut and is distributed throughout the central nervous system its highest concentration is in the hypothalamus and in the substantia gelatinosa of the spinal cord (119). Its overall brain distribution is not unlike that of enkephalin ( ) ... 

Biologica.1 Activities a.ndAna.logues, The many pharmacological actions of neurotensin include hypotension, increased vascular permeabihty, hyperglycemia, increased intestinal motility, and inhibition of gastric acid secretion (120). In the brain, it produces analgesia at remarkably low doses (121). 

Acute intoxication with DHBs occurs mainly by the oral route symptoms are close to those induced by phenol poisoning including nausea, vomiting, diarrhea, tachypnea, pulmonary edema, and CNS excitation with possibiUty of seizures followed by CNS depression. Convulsions are more frequent with catechol as well as hypotension due to peripheral vasoconstriction. Hypotension and hepatitis seem more frequent with hydroquinone and resorcinol. Methemoglobinemia and hepatic injury may be noted within a few days after intoxication by DHBs. 

SRIF acts as an excitatory neuromodulator in the CNS inhibiting the release of TRH, corticotropin-releasing hormone (CRH), growth hormone releasing factor (GHRH), and NE. It produces general arousal and hypotension. It inhibits the release of a number of peptides and modulators in the GI tract. 

Eupatin (69, R = H) and Eupatoretin (69, R = CH3), which are isolated from thistle perennials, show moderate cytotoxicity against human carcinoma of the nasopharynx (236). Baicaleia (70) salts exhibit antiallergic and antiinflammatory activity. 3,4,5-Trimethoxyphenoxyacetamides are hypotensives and diuretics and are useful for controlling arrhythmia duting anesthesia (237). 

Isoflurane is a respiratory depressant (71). At concentrations which are associated with surgical levels of anesthesia, there is Htde or no depression of myocardial function. In experimental animals, isoflurane is the safest of the oral clinical agents (72). Cardiac output is maintained despite a decrease in stroke volume. This is usually because of an increase in heart rate. The decrease in blood pressure can be used to produce "deHberate hypotension" necessary for some intracranial procedures (73). This agent produces less sensitization of the human heart to epinephrine relative to the other inhaled anesthetics. Isoflurane potentiates the action of neuromuscular blockers and when used alone can produce sufficient muscle relaxation (74). Of all the inhaled agents currently in use, isoflurane is metabolized to the least extent (75). Unlike halothane, isoflurane does not appear to produce Hver injury and unlike methoxyflurane, isoflurane is not associated with renal toxicity. 

Propanidid. Propanidid [1421-14-3] (Epontol), C gH2yNO, (7) a derivative of the propyl ester of homo vanillic acid, has been in clinical use in Europe for a number of years. Its main advantage is rapid onset of action and a fast recovery which, like etomidate, is because of rapid metaboHsm by esterases rather than redistribution (108). Excretion is rapid 75 to 90% of the dmg is eliminated as metaboUtes within two hours. Propanidid side effects include hypotension, tachycardia, and hyperventilation followed by apnea, as well as excitatory side effects such as tremor and involuntary muscle movement (109). 

Morphine has certain undesirable side effects. Among these are respiratory depression, nausea, and vomiting, depression of the cough reflex, cardiovascular depression and hypotension, smooth muscle contraction (constipation), and histamine release (93). Morphine s onset of action, duration, and low therapeutic indices have prompted a search for a more effective opiate iv anesthetic. Extreme simplification of the complex morphine molecule has resulted in anilido —piperidines, the fentanyl class of extremely potent opiate iv anesthetics (118,119). 

Normally, dietary tyramine is broken down in the gastrointestinal tract by MAO and is not absorbed. In the presence of MAOI, however, all of its potent sympathomimetic actions are seen. Other side effects of MAOI include excessive CNS stimulation, orthostatic hypotension, weight gain, and in rare cases hepatotoxicity. Because the monoamine oxidase inhibitors exhibit greater toxicity, yet no greater therapeutic response than other, newer agents, clinical use has been markedly curtailed. The primary use for MAOIs is in the treatment of atypical depressions, eg, those associated with increased appetite, phobic anxiety, hypersomnolence, and fatigues, but not melancholia (2). 

Agent or class CNS effects Orthostatic hypotension Arrhythmias Anticholinergic effects Weight change... 

Doridosine. Doridosine, AJ -methyhsoguanosine, (35) was isolated from the dorid nudibranchs of Anisodoris nobilis and the sponge, Tedania (106,107). The injection of (35) into the saphenous vein of anesthetized rats produces hypotension and bradycardia almost immediately. The observed changes in the electrocardiograms are minor and indicate Httie interference with conduction of the impulse within the heart (see Cardiovascularagents). 

The Class I agents have many similar side effects and toxicities. The anticholinergic side effects include dry mouth, constipation, and urinary hesitancy and retention. Common gastrointestinal (GI) side effects include nausea, vomiting, diarrhea, and anorexia. Cardiovascular adverse effects are hypotension, tachycardia, arrhythmias, and myocardial depression, especially in patients with congestive heart failure. Common central nervous system (CNS) side effects are headache, dizziness, mental confusion, hallucinations, CNS stimulation, paraesthesias, and convulsions. 

The cardiovascular adverse effects associated with quinidine therapy are hypotension and tachycardia, both of which are related to its a-adrenoceptor blocking actions. The tachycardia may be a reflex adjustment to the fall in blood pressure or may also be a direct action of the dmg on sympathetic nerve terminals leading to an increased release of NE. Quinidine also produces ringing in the ears (cinchonism) (1,2). 

Toxic effects of propranolol are related to its blocking P-adrenoceptor blocking actions. They include cardiac failure, hypotension, hypoglycemia, and bronchospasm. Propranolol is lipophilic and crosses the blood—brain barrier. Complaints of fatigue, lethargy, mental depression, nightmares, hallucinations, and insomnia have been reported. GI side effects include nausea, vomiting, diarrhea, and constipation (1,2). 

Because of its brief half-life and minimal hpid solubihty, the side effects of esmolol are transient and include hypotension, cold extremities, dyspnea (from bronchospasms), bradycardia, nausea, vomiting, and headaches (41). 

The side effects and toxic reactions to verapamil iaclude upper GI upset, constipation, di22iaess, headaches, flushing and burning, edema, hypotension, bradycardia, and various conduction disturbances. Verapamil has negative iaotropic activity and may precipitate heart failure ia patients having ventricular dysfunction (1,2). 

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). 

Adenosine in large doses produces vasodilation resulting in facial flushing, Hghtheadedness, dizziness, and hypotension. Shortness of breath and... 

Amiodarone dilates arteriolar vascular smooth muscle, especiady coronary arteries, and thus exhibits antianginal effects. Its effects on the peripheral vasculature to decrease resistance leads to a decrease in left ventricular stroke work and a decrease in myocardial oxygen consumption. The dmg rarely produces hypotension that requires discontinuation of the dmg (1,2). 

Adverse effects with bretylium include hypotension, nausea, vomiting, parotid gland tenderness, and arrhythmogenesis (1,2). 

Sotalol is rapidly and almost completely (>90%) absorbed. Bioavahabhity of absorbed dmg is 89—100%. Peak plasma levels are achieved in 2—4 h. Sotalol is 50% bound to plasma proteins. Plasma half-life of the compound is about 5.2 h. No metabolites of sotalol have been identified indicating littie metabolism. The dmg is excreted mainly by the kidneys (80—90%) and about 10% is eliminated in the feces. The plasma half-life is prolonged in patients having renal failure. Kinetics of the compound are not affected by changes in liver function (1,2). Sotalol has ah the adverse effects of -adrenoceptor blockers including myocardial depression, bradycardia, transient hypotension, and proarrhythmic effects (1,2). 

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