Antimuscarinic agents side-effects

Ipratropium bromide is an antimuscarinic agent indicated in asthma and in chronic obstructive pulmonary disease but it is more effective in the latter. The drug is available only for inhalation because of the potential side-effects if given orally. 

The case in context Clozapine is a newer antipsychotic that can, like other agents in its class, produce antimuscarinic side effects. Although Ms. Doe had not complained of anticholinergic effects prior to beginning treatment with a moderate dose of diphenhydramine, it is likely that the additive anticholinergic effects of clozapine and diphenhydramine resulted in urinary retention. 

Q9 Tricyclic antidepressants cause sedation and possess several other side effects. The antimuscarinic (atropine-like) effects of these agents include dry mouth, blurred vision, raised intraocular pressure, postural hypotension, impotence, changes in cardiac rhythm and muscle tremors. They can also cause obstruction of the bladder neck, followed by difficulty in initiating micturition. 

Of the systemic antihistamines, the ethanolamines, including diphenhydramine, have significant antimuscarinic activity. In addition, the antipsychotic agents, particularly the phenothiazines such as thioridazine (Mellaril), have well-dociunented anticholinergic properties. Therapeutic doses of tricyclic antidepressants, like amitriptyline hydrochloride (Elavil) and imipramine (Tofranil), produce significant anticholinergic actions and thus have the potential for ocular side effects. 

Category Agent Dose Associated With Antimuscarinic Side Effects (mg)... 

I. Pharmacology. Benztropine is an antimuscarinic agent with pharmacologic activity similar to that of atropine. The dmg also exhibits antihistaminic properties. Benztropine is used tor the treatment of parkinsonism and for the control of ex-trapyramidal side effects associated with neuroleptic use. 

The effect of antimuscarinic agents on the eye is mydriasis, cycloplegia and reduction of lacrimal secretions. These effects are desirable in ophthalmic examination of non-compliant patients (e.g. children) but considered to be side effects (blurred vision, dry [sandy] eye) in the systemic use of these agents. Cyclopentolate and tropicamide... 

Because the tardive syndromes that develop in adults are often irreversible and have no satisfactory treatment, care must be taken to reduce the likelihood of their occurrence. Antipsychotic medication should be prescribed only when necessary and should be withheld periodically to assess the need for continued treatment and to unmask incipient dyskinesia. Thioridazine, a phenothiazine with a piperidine side chain, is an effective antipsychotic agent that seems less likely than most to cause extrapyramidal reactions, perhaps because it has little effect on dopamine receptors in the striatal system. Finally, antimuscarinic drugs should not be prescribed routinely in patients receiving neuroleptics, because the combination may increase the likelihood of dyskinesia. 

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