Side effects autonomic nervous system

In addition, numerous drugs such as neuroleptics and antidepressants produce side effects by modifying the function of the autonomic nervous system. 

Although the Rauwolfia alkaloids show a low degree of acute toxicity, their continued use may be accompanied by serious side effects. One of the most troublesome symptoms observed in the therapeutic use of Rauwolfia alkaloids is nasal congestion and stuffiness, which may be so severe as to necessitate discontinuing of therapy. Increased motility of the bowel, diarrhea, and increased gastric secretion resulting from its action on the autonomic nervous system are frequently observed. Skin eruptions, epistaxis, and peptic ulceration are rare complications. 

Muscarinic effects, mediated by acetylcholine, the primary transmitter of the autonomic nervous system ganglia, are inhibited by the anticholinergic effects exerted by antihistamines. Anticholinergic side effects include dry mouth, urinary retention, blurred vision, and constipation. Because first-generation antihistamines also distribute into the CNS, sedation is a prominent side effect. The development of second-generation antihistamines, such as loratadine and fexofenadine, lack anticholinergic activity and do not distribute into the CNS (Table 31-1). Hence, they are not typically associated with sedation and do not possess antiemetic properties. 

Side Effects Affecting Autonomic Nervous System ... 

A few central nervous system stimulants exhibit predominant central stimulant action, e.g., strychnine, nikethamide, leptazol, picrotoxine, etc. others possess multiple side-effects,. e.g., ephedrine and atropine act on the autonomic nervous system and finally a number of drugs do exert temporary stimulation of CNS in toxic doses, e.g., local anaesthetics, santonin, salicylates. In usual praetiee, the eentral nervous system stimulants find their use in emergencies for prompt and short-term exeitation of CNS, because a prolonged stimulation may be followed by depression. 

Loratadine (LOR) is the most commonly used second-generation antihistamine drug for the symptomatic relief of allergic disorders without significant side effects on the central and autonomic nervous systems (Kaiser et al., 2008 Kay Harris, 1999). One major limited use... 

Side Effects and Toxicity. Adverse effects to the tricycHc antidepressants, primarily the result of the actions of these compounds on either the autonomic, cardiovascular, or central nervous systems, are summarized in Table 3. The most serious side effects of the tricycHcs concern the cardiovascular system. Arrhythmias, which are dose-dependent and rarely occur at therapeutic plasma levels, can be life-threatening. In order to prevent adverse effects, as weU as to be certain that the patient has taken enough dmg to be effective, the steady-state semm levels of tricycHc antidepressant dmgs are monitored as a matter of good practice. A comprehensive review of stmcture—activity relationships among the tricycHc antidepressants is available (42). 

In humans, a prominent effect of cocaine consists in increased vigilance and elevated mood. While cocaine itself is not used clinically, several catecholamine and serotonin reuptake blockers are used as antidepressants. Imipramine (Figure 10.13) is a classic but not so very specific in addition to inhibiting the reuptake of serotonin and of norepinephrine, it also has antihistaminic and antimuscarinic activity. This will lead to side effects in both the central nervous system and the peripheral autonomic system. A prominent one is the causation or deterioration of cardiac arrhythmias due to its antimuscarinic action. 

The autonomous, sustained production of AVP in the absence of known stimuli for its release is called SIADH. In this syndrome, plasma AVP concentrations are inappropriately increased relative to a low plasma osmolality and to a normal or increased plasma volume. SIADH may be the result of one of several factors production of vasopressin by a malignancy (such as a small cell carcinoma of the lung), the presence of acute and chronic diseases of the central nervous system, pulmonary disorders, or a side effect of certain drug therapies. In addition, as many as 10% of patients undergoing pituitary surgery have a transient SIADH approximately 8 to 9 days after surgery (when the patient is at home), which responds to water restriction (2 to 3 days) and resolves without recurrence. In SIADH, a primary excess of AVP, coupled with unrestricted fluid intake, promotes increased reabsorption of free water by the kidney. The result is a decreased urine volume and an increased urine sodium concentration and urine osmolality. As a consequence of water retention, these patients become modestly volume expanded. The increase in intravascular volume causes hemodilution accompanied by dilutional hyponatremia and a low plasma osmolality. Volume expan-... 

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