What treatment options are available for a patient with constipation, considering their age, medical history, and current medication regimen?

Treatment Options for Constipation

Start with polyethylene glycol (PEG) 17g mixed with 8 oz water twice daily as first-line therapy for constipation, as it has the strongest safety profile for long-term use and proven efficacy across all patient populations. 1, 2, 3

First-Line Pharmacological Treatment

• PEG 17g twice daily (total 34g/day) is the preferred initial therapy due to virtually no net electrolyte disturbance and proven safety for continuous use beyond 12 months 1, 2
• If no bowel movement occurs within 3-4 days on PEG, escalate to adding a stimulant laxative rather than increasing PEG dose further 3
• Lactulose 30-60 mL daily is an alternative osmotic agent, though it has a 2-3 day latency period and causes more bloating than PEG 1

Add-On Therapy for Inadequate Response

• Add bisacodyl 10-15 mg daily if constipation persists after 24-48 hours of PEG therapy, with maximum dose of 10 mg orally daily for regular use 1
• Senna is an effective alternative stimulant, typically dosed as 2 tablets every morning with maximum of 8-12 tablets per day 1
• The goal is to achieve one non-forced bowel movement every 1-2 days 4, 1

Prophylactic Strategy (Critical for High-Risk Patients)

• Prophylactic laxatives must be prescribed at initiation of opioid therapy or antipsychotic medications like haloperidol—never wait for constipation to develop 1
• The prophylactic regimen should include either a stimulant laxative (senna or bisacodyl) or PEG 17g twice daily 1
• For opioid-induced constipation specifically, a stimulant laxative with or without stool softener, or PEG twice daily, should be started immediately 4

Management of Persistent Constipation

• If constipation persists despite optimized oral laxatives, perform digital rectal examination to rule out fecal impaction and bowel obstruction 1, 2
• Consider adding metoclopramide 10-20 mg PO four times daily as a prokinetic agent to enhance gastric antral contractility, though chronic use carries tardive dyskinesia risk 4, 1
• Magnesium hydroxide 30-60 mL daily provides rapid bowel evacuation when needed, but use cautiously and only with confirmed normal renal function due to hypermagnesemia risk 1, 2, 3

Management of Fecal Impaction

• Perform digital fragmentation and extraction of stool, followed by water or oil retention enema or suppository to facilitate passage 2
• Once the distal colon is partially emptied, administer PEG orally to prevent recurrence 2
• Use isotonic saline enemas (500-1000 mL) rather than sodium phosphate enemas, especially in elderly patients, as they have fewer adverse effects 2, 3

Special Considerations for Elderly Patients

• PEG 17g daily is the preferred first-line agent for elderly patients due to excellent safety profile 2, 3
• Ensure easy toilet access for patients with decreased mobility 2, 3
• Educate patients to attempt defecation twice daily, 30 minutes after meals, straining no more than 5 minutes 2, 3
• Increase fluid intake to at least 1.5 liters daily within patient limits 2, 3
• Avoid bulk-forming laxatives (psyllium, methylcellulose) in non-ambulatory patients with low fluid intake due to obstruction risk 2, 3

Advanced Options for Refractory Cases

• Linaclotide 145 mcg orally once daily on an empty stomach is FDA-approved for chronic idiopathic constipation in adults 5
• For pediatric patients 6-17 years with functional constipation, linaclotide 72 mcg once daily is approved 5
• Methylnaltrexone (subcutaneous opioid antagonist) can be used as rescue therapy when constipation is clearly related to opioid therapy and laxatives have failed 4

Critical Pitfalls to Avoid

• Never use stool softeners (docusate) alone without stimulant or osmotic laxatives—they lack efficacy for medication-induced constipation 1, 3
• Never wait for constipation to develop before starting laxatives in patients on opioids or antipsychotics, as this causes unnecessary suffering and can lead to paralytic ileus 1
• Always rule out bowel obstruction before escalating laxative therapy, particularly if symptoms worsen despite treatment 4, 1, 2
• Avoid magnesium-containing laxatives in patients with any degree of renal impairment due to hypermagnesemia risk 1, 2, 3
• Avoid liquid paraffin in bed-bound patients or those with swallowing difficulties due to aspiration lipoid pneumonia risk 2, 3
• Do not use supplemental medicinal fiber (psyllium) for opioid-induced constipation—it is ineffective 4

Medication Review

• Review and discontinue non-essential constipating medications when possible 2
• For patients on quetiapine causing constipation, consider tapering when used for behavioral control in cognitive disease, as it is safe to taper off when there is perceived lack of benefit 3

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