Antimuscarinic effect, drugs causing

Sympathomimetic effects (from NA re-uptake inhibition) and antimuscarinic effects can cause a sinus tachycardia. Postural hypotension may occur as a result of sympatholytic al-adrenoceptor antagonism. With overdoses of these drugs, there is a reduced re-uptake of catecholamines, resulting in arrhythmias and hypertension. Tricyclic compounds have a high... 

The answer is a. (Hardman, p 436.) The most common side effects associated with tricyclic antidepressants are their antimuscarinic effects, which may be evident in over 50% of patients. Clinically, the antimuscarinic effects may manifest as dry mouth, blurred vision, constipation, tachycardia, dizziness, and urinary retention. At therapeutic plasma concentrations, these drugs usually do not cause changes in the EKG. Direct cardiac effects of the tricyclic antidepressants are important in overdosage. 

Certain vestibular disorders respond to antimuscarinic drugs (and to antihistaminic agents with antimuscarinic effects). Scopolamine is one of the oldest remedies for seasickness and is as effective as any more recently introduced agent. It can be given by injection or by mouth or as a transdermal patch. The patch formulation produces significant blood levels over 48-72 hours. Useful doses by any route usually cause significant sedation and dry mouth. 

Imipramine, a tricyclic antidepressant drug with strong antimuscarinic actions, has long been used to reduce incontinence in institutionalized elderly patients. It is moderately effective but causes significant CNS toxicity. Propiverine, a newer antimuscarinic agent, has been approved for this purpose. 

TCAs NITRATES 1. t risk of antimuscarinic side-effects when isosorbide dinitrate is co-administered with TCAs 2. i efficacy of sublingual nitrate tablets with TCAs 1. Additive effect both of these drugs cause antimuscarinic side-effects 2. Antimuscarinic effects i saliva production, which i dissolution of the tablet 1. Warn patients of this additive effect 2. Consider changing the formulation to a sublingual nitrate spray... 

AMANTADINE ANTIMUSCARINICS t risk of antimuscarinic side-effects Additive effect both drugs cause antimuscarinic side-effects Warn patient of this additive effect... 

Pilocarpine is used as a miotic agent in the therapy of glaucoma, and is also used in the therapy of xerostomia caused by drugs with a high degree of antimuscarinic effects. 

D. Toxicity and Interactions Sedation is common, especially with diphenhydramine, doxylamine, and promethazine. It is much less common with second-generation agents, which do not enter the CNS readily. Antimuscarinic effects such as dry mouth and blurred vision occur with some first-generation drugs in some patients. Alpha-blocking actions may cause orthostatic hypotension. 

Additive effect both of these drugs cause antimuscarinic side-effects 2. Antimuscarinic effects i saliva production, which i dissolution of the tablet... 

Detailed information about adverse interactions between nefopam and other drugs does not seem to be available. The manufacturer advises caution if nefopam is given with a tricyclic antidepressant because they lower the convulsive threshold convulsions have been seen in some patients taking nefopam. In addition, the antimuscarinic adverse effects of nefopam may be additive with those of tricyclics and other drugs with antimuscarinic effects. For example, the CSM in the UK has a number of reports of urinary retention caused by nefopam, which would be expected to be worsened by drugs with antimuscarinic activity. Nefopam appears to have sympathomimetic activity and the manufacturer therefore says it should not be given with the MAOIs (see MAOIs or RIMAs + Sym-pathomimetics Indirectly-acting , p.l 147). 

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