What are the guidelines for initiating anti-cholinergic (anticholinergic) therapy?

Guidelines for Initiating Anticholinergic Therapy

Anticholinergic medications should only be used as second-line therapy after other treatments have failed, and should be prescribed for the shortest duration possible at the lowest effective dose due to their significant side effect profile. 1, 2

Indications for Anticholinergic Therapy

• Extrapyramidal Side Effects (EPS): Anticholinergics should be used for treating acute dystonia associated with antipsychotic therapy, but should not be used routinely for preventing EPS 1
• Parkinsonism: For patients with antipsychotic-induced parkinsonism, consider lowering the antipsychotic dose or switching to another antipsychotic before initiating anticholinergic therapy 1
• Sialorrhea (Excessive Salivation): A therapeutic trial of an anticholinergic medication is recommended as first-line therapy for patients with neuromuscular disorders and sialorrhea, with continued use only if benefits outweigh side effects 1
• Motion Sickness/PONV: Scopolamine transdermal system is indicated for prevention of nausea and vomiting associated with motion sickness and post-operative nausea and vomiting 3

Patient Selection and Assessment

• Avoid in Elderly: Carefully assess risk-benefit in older adults due to increased risk of cognitive impairment, falls, and other adverse effects 4, 5
• Contraindications: Do not use in patients with angle-closure glaucoma 3
• Caution in:
  • Patients with open-angle glaucoma (monitor intraocular pressure) 3
  • Patients with cognitive impairment or at risk for dementia 6
  • Patients with intestinal obstruction, pyloric obstruction, or urinary retention 3
  • Pregnant women with severe preeclampsia (risk of eclamptic seizures) 3

Dosing and Administration

• For Antipsychotic-Induced EPS:

  • Start with the lowest effective dose and titrate based on response 1
  • Only use for acute dystonia or when dose reduction and switching strategies have proven ineffective 1
  • For sialorrhea, start with an inexpensive oral anticholinergic medication before considering more expensive patch formulations 1

• For Motion Sickness (Scopolamine Transdermal):

  • Apply one transdermal system to hairless area behind one ear at least 4 hours before antiemetic effect is required 3
  • For use up to 3 days; if longer therapy needed, remove first patch and apply new one behind the other ear 3

Monitoring and Follow-up

• Regular Assessment: Evaluate for anticholinergic side effects at each follow-up visit 7
• Cognitive Monitoring: Monitor for neuropsychiatric adverse reactions, including cognitive effects and seizures 3
• Physical Monitoring: Watch for dry mouth, constipation, urinary retention, blurred vision, and drowsiness 8
• Withdrawal Symptoms: Be aware that anticholinergic symptoms may occur 24 hours or more after removal of transdermal systems 3

Managing Side Effects

• Common Side Effects:

  • Dry mouth (53%), dry eyes (53%), drowsiness (65%), constipation (39%), blurred vision (39%), urinary hesitancy (28%), and confusion (21%) 8
  • For motion sickness: dry mouth, drowsiness, blurred vision, and pupil dilation (>15%) 3

• Serious Adverse Effects:

  • Cognitive impairment and increased risk of dementia with long-term use 6
  • Acute angle-closure glaucoma 3
  • Falls, especially in elderly patients 4

Discontinuation Strategies

• Gradual Tapering: Reduce dose gradually to avoid withdrawal symptoms 7
• Regular Reassessment: For patients on long-term therapy, regularly assess the need for continued treatment 7
• Consider Alternatives: For antipsychotic-induced EPS, consider switching to an antipsychotic with lower EPS risk before continuing anticholinergic therapy 1

Special Considerations

• Anticholinergic Burden: Be aware of the cumulative anticholinergic effect when multiple medications with anticholinergic properties are prescribed 4, 5
• Route of Administration: For patients with sialorrhea who have inadequate response to oral anticholinergics, consider botulinum toxin therapy to salivary glands 1
• Medication Delivery: When using anticholinergics with inhaled therapy, consider using a mouthpiece rather than face mask to avoid the risk of acute glaucoma or blurred vision in elderly patients 1