Anticholinergic drugs side effects

Pharmacotherapy. The currently available treatments for PD are symptomatic, and do not alter the course of the disease. The earliest treatment that is still in limited use today, is with the anticholinergic medications, such as trihexiphenidyl or benzotropine. These drugs are useful, particularly for tremor. However, their use is often prob-lematic because of unpleasant side-effects, such as memory disturbances, blurred vision, sedation, dry mouth, or urinary retention, particularly in older patients. 

Anticholinergic drugs, such as atropine, block vagal tone and prolong gut transit time. Their value in controlling diarrhea is questionable and limited by side effects. 

Medications for symptomatic relief from vertigo consist of antiemetics, benzodiazepines and antihistamines. They are all mostly aimed at the psychological consequences of dizziness and can all have highly unfavourable side effects, for example, sedation, anticholinergic effects and insomnia. The psychological consequences of dizziness in elderly should rather be treated with information about the condition, supportive help actions and increased social activities, than with drugs. 

With the possible exception of maprotiline, which is chemically a modified TCA with all the side effects attributable to such a molecule, all of the newer non-tricyclic drugs have fewer anticholinergic effects and are less cardiotoxic than the older tricyclics. Lofepramine is an example of a modified tricyclic that, due to the absence of a free NH2 group in the side chain, is relatively devoid of anticholinergic side effects. Thus by slightly modifying the structure of the side chain it is possible to retain the efficacy while reducing the cardiotoxicity. 

In the event of increased anticholinergic side effects, plasma levels of disopyramide should be monitored and the dose of the drug adjusted accordingly. A reduction of the dose by one third, from the recommended 600 mg/day to 400 mg/day, would be... 

Renal/Hepatic function impairment Use with caution and in reduced doses in patients with hepatic impairment metabolism may be impaired, leading to drug accumulation. Use with caution in patients with significantly impaired renal function. Elderly Be cautious in dose selection for an elderly patient, usually starting at the low end of the dosing range. Elderly patients may be sensitive to the anticholinergic side effects of TCAs. 

Atropine A subtherapeutic dose of atropine has been added to difenoxin to discourage deliberate overdosage. A recommended dose is not likely to cause prominent anticholinergic side effects, but avoid in patients in whom anticholinergic drugs are P.833... 

Although atropine and related compounds possess bronchodilator activity, their use is associated with the typical spectrum of anticholinergic side effects (see Chapter 13), and they are no longer used in the treatment of asthma. To improve the clinical utility of anticholinergics, quaternary amine derivatives of atropine were developed. By virtue of their positive charge, these drugs are absorbed poorly across mucosal surfaces and thus produce fewer side effects than atropine, especially when given by inhalation. 

Geriatric Considerations - Summary Bupropion has several advantages as an antidepressant agent for use in older adults. It has neither the anticholinergic or cardiac toxicities of the tricyclic antidepressants, and has fewer sexual side effects than selective serotonin reuptake inhibitors. Because this drug may lower seizure threshold, it should be used with caution in older adults with increased risk of seizures (e.g., previous stroke, early-onset Alzheimer s disease). 

Geriatric Considerations - Summary Glycopyrrolate does not cross the blood-brain barrier so is less likely to cause the central effects seen with anticholinergics such as atropine. Other anticholinergic side effects such as blurred vision, dry mouth, urinary retention, and constipation do occur and can limit the usefulness of this drug in the older adult. 

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