Anticholinergics: Generic and Brand Names
Here is a table of commonly encountered anticholinergic agents, their generic names, and brand names:
- Anticholinergics
- atropine sulfate
- ipratropium (Atrovent)
- meclizine (Bonine, Antivert)
- methscopolamine (Pamine)
- scopolamine (Transderm Scop)
- tiotropium (Spiriva)
Disease Spotlight: Gastrointestinal Ulcers
Anticholinergics were once widely used to cut GI activity and secretions, but more specific, less toxic drugs have narrowed their role. GI ulcers are erosions in the GI lining caused by increased HCl production, most often from H. pylori infection, and produce burning abdominal pain, nausea, and acid reflux.
Therapeutic Action
Anticholinergics competitively block ACh at muscarinic cholinergic receptor sites, which mediate parasympathetic postganglionic impulses. Atropine, the prototype, is derived from belladonna. It depresses salivation and bronchial secretions and dilates the bronchi, but it can thicken respiratory secretions enough to obstruct the airway. Atropine and scopolamine block only the muscarinic effectors in the parasympathetic nervous system plus the few cholinergic receptors in the sympathetic nervous system.
Indications
Anticholinergics prevent nausea, vomiting, and dizziness from motion sickness; serve as adjunctive therapy for GI ulcers; decrease secretions before anesthesia or intubation; maintain treatment of bronchospasm in COPD; and treat irritable or hyperactive bowel in adults.
Across age groups: children are more sensitive to adverse effects (constipation, urinary retention, heat intolerance, confusion), and dicyclomine is not recommended for them. Adults should be warned about adverse effects, and these drugs are not used in pregnancy because they cross the placenta and harm the fetus. Older adults need dose adjustment and are more likely to reach toxic levels because of renal or hepatic impairment; the American Geriatrics Society Beers Criteria list drugs with strong anticholinergic activity among those to avoid in older adults because of confusion, falls, urinary retention, and constipation.
Pharmacokinetics
Here are the characteristic interactions of anticholinergics and the body in terms of absorption, distribution, metabolism, and excretion:
| Route | Onset | Peak | Duration |
|---|---|---|---|
| IM | 10-15 min | 30 min | 4 h |
| IV | Immediate | 2-4 min | 4 h |
| Subcutaneous | Varies | 1-2 h | 4 h |
| Topical | 5-10 min | 30-40 min | 7-14 d |
| Half-life (T1/2) | Metabolism | Excretion |
|---|---|---|
| 2.5 h | liver | urine |
Contraindications and Cautions
Avoid with allergy to any component. Glaucoma is exacerbated by parasympathetic blockade. Intestinal atony, paralytic ileus, and GI obstruction worsen as GI activity slows further. Avoid in pregnancy because of adverse fetal effects.
Adverse Effects
CNS: blurred vision, pupil dilation, photophobia, cycloplegia, increased intraocular pressure, weakness, dizziness, insomnia. CV: tachycardia, palpitation. GI: dry mouth, altered taste, nausea, heartburn, constipation. GU: urinary hesitancy and retention, heat prostration.
Interactions
Antihistamines, antiparkinsonism drugs, MAOIs, and TCAs carry their own anticholinergic effects, so combining them increases the burden. Phenothiazines lose effectiveness. Burdock, rosemary, and turmeric risk exacerbated anticholinergic effects.
Nursing Considerations
Before giving an anticholinergic, assess for contraindications and cautions (allergy, GI obstruction, hepatorenal dysfunction), establish a baseline physical exam, and check neurological status (orientation, affect, reflexes) for CNS effects. Assess the abdomen (bowel sounds, bowel and bladder patterns, urine output) for GI and GU effects, and monitor labs for dose adjustments and early toxicity.
Likely nursing diagnoses include acute pain from GI, CNS, GU, and CV effects; decreased cardiac output from CV effects; impaired urinary elimination from bladder effects; and constipation from GI effects.
Give the drug correctly to keep it effective and limit adverse effects. Monitor blood pressure, ECG, and urine output for changes that signal a needed dose adjustment. Offer comfort measures (sugarless lozenges, lighting control, small frequent meals) and teach the patient the drug's effects and the warning signs to report.
To evaluate, track improvement in the treated condition, watch for adverse effects (photophobia, heat intolerance, urinary retention), confirm understanding by having the patient name the drug, its indication, and adverse effects to watch for, and monitor compliance.
Frequently Asked Questions
What does "anticholinergic" actually block?
These drugs competitively block acetylcholine at muscarinic receptors, the receptors that carry parasympathetic ("rest and digest") signals. With those signals damped, secretions dry up, the heart rate climbs, the pupils dilate, the bladder and bowel slow, and sweating drops (StatPearls).
What is the classic anticholinergic side-effect picture?
Students memorize it as "dry as a bone, red as a beet, blind as a bat, mad as a hatter, hot as a hare": dry mouth and dry skin, flushing, blurred vision and dilated pupils, confusion, and impaired heat loss. Tachycardia, constipation, and urinary retention round out the cluster.
Why are anticholinergics risky in older adults?
The aging brain has fewer cholinergic neurons and the liver and kidneys clear drugs more slowly, so older adults are more prone to confusion, delirium, falls, urinary retention, and constipation. The American Geriatrics Society Beers Criteria flag strongly anticholinergic drugs as potentially inappropriate in this group.
Why is atropine given before anesthesia or for bradycardia?
Atropine blocks vagal (parasympathetic) input to the heart, which raises the heart rate, and it dries respiratory and oral secretions before intubation. That same vagolytic effect makes it a first-line drug for symptomatic bradycardia.
Which patients should usually avoid anticholinergics?
Avoid them in narrow-angle glaucoma (they raise intraocular pressure), in paralytic ileus or GI obstruction and bladder outlet obstruction (they slow motility and retain urine), and generally in pregnancy. Use caution with renal or hepatic impairment and in anyone already on other anticholinergic drugs, since the burden stacks.
Do antihistamines and antidepressants count as anticholinergics?
Many do. First-generation antihistamines, tricyclic antidepressants, some antipsychotics, and antiparkinsonian drugs all carry anticholinergic activity, so combining them with a dedicated anticholinergic multiplies dry mouth, constipation, urinary retention, and confusion.