Gastrointestinal system anticholinergics

Because of the multiple receptor sites that TCAs bind to, there are a variety of possible side effects that can be seen in treatment. The blockade of muscarinic receptors leads to increased anticholinergic tone and subsequent anti-cholinergic side effects, especially in the gastrointestinal system. These include delirium, dry mouth, tachycardia, constipation, and urinary retention in adults. In children, anticholinergic side effects are often not seen with treatment (Geller et ah, 1992). Tricyclic antidepressant blockade of the presynaptic a 2 receptors leads to increased autonomic tone throughout the body, causing elevations in heart rate and blood pressure. 

See also Anticholinergics Atropine Charcoal Deferoxamine Gastrointestinal System Lithium Pesticides Polyethylene Glycol Pyridoxine. 

The Class I agents have many similar side effects and toxicities. The anticholinergic side effects include dry mouth, constipation, and urinary hesitancy and retention. Common gastrointestinal (GI) side effects include nausea, vomiting, diarrhea, and anorexia. Cardiovascular adverse effects are hypotension, tachycardia, arrhythmias, and myocardial depression, especially in patients with congestive heart failure. Common central nervous system (CNS) side effects are headache, dizziness, mental confusion, hallucinations, CNS stimulation, paraesthesias, and convulsions. 

These dragp are used with caution in patients with tachycardia, cardiac arrhythmias, hypertension, hypotension, those with a tendency toward urinary retention, those with decreased liver or kidney function, and those with obstructive disease of the urinary system or gastrointestinal tract. The anticholinergic drugp are given with caution to the older adult. 

Anticholinergics -gastrointestinal agents [GASTROINTESTINAL AGENTS] (Vol 12) -role in drug delivery [DRUG DELIVERY SYSTEMS] (Vol 8)... 

The primary clinical applications of antimuscarinic anticholinergic drugs include the treatment of certain gastrointestinal disorders. These drugs may also be helpful in managing Parkinson disease. In addition, they have been used to treat a variety clinical disorders involving other physiologic systems.5 The clinical ap-... 

Diphenoxylate is a narcotic-like substance that slows gastrointestinal motility and depresses the central nervous system producing coma and respiratory depression. Anticholinergic effects (secondary to the presence of atropine as an abuse deterrent) can be seen early after exposure with opioid effects occurring later. There is no correlation between the dose ingested and the severity of effects in children. Severe poisonings with coma and respiratory depression have been reported in children with small ingestions. 

Emerging evidence suggests that the high incidence of adverse effects, especially dry mouth, of oxybutynin IR, and to a lesser extent oxybutynin extended-release (XL) and oxybutynin transder-mal system (TDS), may be largely due to the active metabolite, A-desethyloxybutynin (DEO). This metabofite is generated by extensive first-pass metabolism in the liver and upper gastrointestinal tract. ° Since many of the adverse effects seen with oxybutynin are felt to be related to the primary hepatic metabolite DEO, the lower DEO plasma concentrations seen with oxybutynin TDS and oxybutynin XL (which are due to reduced first-pass metabolism) compared to those of oxybutynin IR may explain their lesser propensity to cause dry mouth and other anticholinergic adverse effects. 

---