Lomotil Dosing in Elderly Patients
For elderly patients (≥65 years), start Lomotil at a reduced dose of 2.5 mg diphenoxylate/0.025 mg atropine, 1-2 times daily, and adjust based on response and tolerability—this is lower than standard adult dosing due to increased sensitivity to anticholinergic effects. 1
Initial Dosing Strategy
- Begin with 2.5 mg diphenoxylate/0.025 mg atropine (one tablet), 1-2 times daily rather than the standard adult dose of 5 mg four times daily 1
- The dose reduction is necessary because elderly patients demonstrate heightened susceptibility to anticholinergic side effects from the atropine component 1
- Titrate slowly based on clinical response and tolerability, avoiding rapid dose escalation 1
Critical Monitoring Parameters
Watch closely for anticholinergic toxicity signs, which are more pronounced in elderly patients: 1
- Urinary retention (particularly problematic in elderly men with prostatic hypertrophy)
- Constipation (can worsen existing bowel dysfunction)
- Blurred vision and dry mouth
- Confusion and cognitive impairment (CNS effects are amplified in this age group)
- CNS depression and sedation 1
Special Populations Requiring Further Dose Reduction
- Renal impairment: Further dose reduction is necessary due to potential drug accumulation 1
- Hepatic impairment: Avoid Lomotil entirely in severe hepatic disease, as diphenoxylate undergoes hepatic metabolism 1
Critical Prescribing Pitfalls to Avoid
- Never prescribe standard adult doses (5 mg four times daily) to elderly patients—this dramatically increases adverse effect risk 1
- Avoid combining with other anticholinergic medications (antihistamines, tricyclic antidepressants, bladder antimuscarinics) as this creates additive toxicity 1
- Limit duration of use: Prolonged therapy requires careful monitoring and should not continue indefinitely without reassessment 1
Preferred Alternative
Consider loperamide as a first-line alternative in elderly patients, as it offers several advantages: 1
- Does not cross the blood-brain barrier, minimizing CNS side effects
- Lacks the atropine component, eliminating anticholinergic toxicity risk
- Demonstrates fewer central effects overall compared to diphenoxylate