What is the recommended dose of Neostigmine (neostigmine) for a patient with persistent ileus, considering their past medical history and potential for hypotension, bradycardia, and bronchospasm?

Neostigmine Dosing for Persistent Ileus

For persistent ileus, administer neostigmine 2 mg intravenously over 3-5 minutes with continuous cardiac monitoring and atropine readily available. 1, 2

Dosing Protocol

Standard dose for ileus is 2 mg IV bolus administered slowly over 3-5 minutes, which differs from the weight-based dosing used for neuromuscular blockade reversal (0.03-0.07 mg/kg). 1, 3, 2

• The 2 mg dose has been validated in multiple randomized controlled trials specifically for acute colonic pseudo-obstruction and ileus, with response rates of 89-94% 3, 2
• Median time to clinical response (passage of flatus/stool and reduced abdominal distention) is 4 minutes (range 3-30 minutes) 3, 2
• Maximum total dose should not exceed 5 mg 1

Alternative Dosing Strategy

For critically ill ICU patients with prolonged ileus, continuous infusion of 0.4-0.8 mg/hour over 24 hours is an effective alternative, with 79% achieving defecation without serious acute adverse effects. 4

Mandatory Pre-Administration Requirements

Atropine or glycopyrrolate must be immediately available before neostigmine administration, and should be given prophylactically if bradycardia (heart rate <60 bpm) is present. 1

• Continuous electrocardiographic monitoring is required during and after administration 1, 3
• Ensure patent airway and adequate ventilation capacity 1
• Verify no mechanical obstruction via imaging before administration 1

Absolute Contraindications

Do not administer neostigmine if any of the following are present: 1, 3

• Peritonitis or mechanical bowel obstruction 1
• Bradycardia (heart rate <60 bpm) without prior atropine administration 3
• Hypotension (systolic BP <90 mmHg) 3
• Active bronchospasm or severe reactive airway disease 1, 3
• Clinical or radiographic evidence of perforation 3
• Known hypersensitivity to neostigmine 1

High-Risk Populations Requiring Extreme Caution

Use with heightened vigilance in patients with: 1

• Coronary artery disease, cardiac arrhythmias, or recent acute coronary syndrome—these patients have increased risk of bradycardia, hypotension, and dysrhythmias 1
• Myasthenia gravis—risk of cholinergic crisis 1
• Serum creatinine >3 mg/dL 3

Expected Response and Monitoring

Clinical response should occur within 4-30 minutes, manifested by passage of flatus or stool with decreased abdominal distention on physical examination. 5, 3, 2

• If no response within 3 hours, a second dose of 2 mg may be administered 3, 2
• Sustained response is defined as decreased abdominal girth and reduced colonic dilation on radiographs 3 hours post-infusion 3
• Continue monitoring for recurrence, as 10-27% may require repeat dosing or colonoscopic decompression 3, 2

Common Adverse Effects and Management

Abdominal cramping occurs in approximately 50-70% of patients but is usually mild and self-limited. 3, 2

• Symptomatic bradycardia requiring atropine occurs in approximately 10-20% of patients 3, 2
• Other effects include excess salivation, nausea, and vomiting 2
• Rare but serious: ischemic colonic complications may occur 7-10 days post-treatment in critically ill patients 4

Critical Pitfall to Avoid

Do not confuse the 2 mg bolus dose for ileus with the weight-based dosing (0.03-0.07 mg/kg) used for neuromuscular blockade reversal—these are distinct clinical indications with different dosing strategies. 1, 3, 2