Guanethidine affected

Literature on the effect of guanethidine on other natural tissue amines is scanty. In rats, up to about 50 per cent depletion of 5-hydroxytryptamine has been reported in the brain [211], thyroid [333], duodenum [211] and small intestine [334, 335], but no depletion has been observed in the spleen or ileum [21 1,334]. Guanethidine does not affect rat-heart histamine [336]. 

Guanethidine is used for severe hypertension when the use of the more generally accepted drngs turns out to be unsuccessful. It is a powerful, long-lasting antihypertensive drug however, it affects a patient s blood pressure only in the orthostatic position, and not when lying down. 

Drugs that may affect nasal decongestants include beta blockers, furazolidone, guanethidine, methyidopa, MAO inhibitors, rauwolfia alkaloids, tricyclic antidepressants, urinary acidifiers, and urinary alkalinizers. 

Drugs that may be affected by nasal decongestants include guanethidine. 

Drugs that may be affected by tricyclic compounds include anticholinergics, carbamazepine, clonidine, dicumarol, grepafloxacin, guanethidine, levodopa, quinolones, sparfloxacin, and sympathomimetics. 

Drugs that may be affected by phenothiazines include anticholinergics, beta-blockers, guanethidine, meperidine, oral anticoagulants, phenytoin, thiazide diuretics, and dofetilide. 

Drugs that may affect methylphenidate include MAOIs. Drugs that may be affected by methylphenidate hydrochloride include guanethidine, anticonvulsants (eg, phenytoin, phenobarbital, primidone), selective serotonin reuptake inhibitors, coumarin anticoagulants, and tricyclic antidepressants. 

Guanethidine possesses high af nity for the axolemmal and vesicular amine transporters. It is stored instead of NE, but is unable to mimic functions of the latter. In addition, it stabilizes the axonal membrane, thereby impeding the propagation of impulses into the sympathetic nerve terminals. Storage and release of epinephrine from the adrenal medulla are not affected, owing to the absence of a reuptake process. The drug does not cross the blood-brain barrier. 

Several conditions may adversely affect the abihty of guanethidine to lower the upper eyehd (1) if the patient is thyrotoxic rather than euthyroid or hypothyroid (2) if the patient is concomitantly imdergoing drug therapy with adrenergic agonists, either systemically or topically and (3) if adhesions form between the levator and the superior rectus muscles in the later stages of the disease process. 

Although vesicles bind either NA or ADR. the storage mechanism is not specific for these amines. Other related compounds can also be bound within medullary or neuronal vesicles. For example, L-metaraminol and p-tyramine can stoichiometrically replace the endogenous catecholamine, without affecting the ATP content of the storage vesicles. Many other amines will bind in a similar manner, e.g. guanethidine and 5-hydroxytryptamine. 

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