💊 MISCELLANEOUS AGENTS FOR CONSTIPATION

These meds don’t fit into laxatives, cathartics, or GC-C agonists, but they’re still very important for special cases like hepatic encephalopathy, opioid constipation, and IBS-C in women.

🧠 1. Lactulose (Constulose, Kristalose)

🔬 Class: Hyperosmotic agent / Synthetic sugar (disaccharide)
⚙ Mechanism of Action:

  • Pulls water into the colon → softens stool

  • Lowers colon pH by producing lactic + acetic acid

  • Converts ammonia (NH₃) → ammonium (NH₄⁺) which gets trapped and excreted

💡 Used for:

  • Constipation

  • Hepatic encephalopathy → lowers blood ammonia!

🩺 Dosing

  • Constipation: 10–20 g (15–30 mL) PO daily

  • Encephalopathy: 20–30 g (30–45 mL) PO 3–4×/day, adjust to get 2–3 soft stools/day

  • Enema: 300 mL lactulose + 700 mL saline/water

⚠ Adverse Effects

  • Electrolyte imbalances

  • Dehydration

  • Gas, bloating, cramps

💡 Concept Mastery Tip:

Lactulose is dual-purpose: pulls water into stool AND traps ammonia in the gut → this makes it vital for patients with cirrhosis or hepatic encephalopathy.

💠 2. Lubiprostone (Amitiza)

🔬 Class: Chloride channel activator
⚙ Action:

  • Activates chloride channels on intestinal cells → increases intestinal fluid secretion → stimulates motility

  • Works locally, bypasses opioid suppression of motility

✅ Indications:

  • Chronic idiopathic constipation (CIC)

  • Opioid-induced constipation

  • IBS-C in women ≥18 only (not studied in men!)

🩺 Dosage:

  • CIC/Opioid constipation: 24 mcg PO BID with food

  • IBS-C in women ≥18: 8 mcg PO BID with food

⚠ Adverse Effects:

  • Nausea (especially in older adults) → take with food

  • Severe diarrhea, dyspnea, hypotension, syncope

  • Methadone may reduce effectiveness!

🚫 Avoid in:

  • Pregnant women (limited data)

  • Not approved for children

💡 Dyspnea often resolves in a few hours — monitor BP closely if patient is also on antihypertensives.

🧪 3. Sorbitol

🔬 Class: Hyperosmotic monosaccharide
⚙ Action:

  • Pulls water into bowel via osmotic pressure

  • Can be given orally or rectally

  • Used with:

    • Sodium polystyrene sulfonate (Kayexalate) for hyperkalemia

    • Activated charcoal for poisoning

🩺 Dosage:

  • PO: 30–150 mL of 70% solution

  • Rectal enema: 120 mL of 25–30% solution

  • Doses lower in children

⚠ Notes:

  • Safe in pregnancy

  • Monitor for diarrhea, dehydration

👩🏽 4. Tegaserod (Zelnorm)

🔬 Class: Serotonin (5-HT₄) receptor agonist
⚙ Action:

  • Stimulates GI motility

  • Used short-term for IBS-C in women <65 y

🩺 Dosage:

  • 6 mg PO twice daily before meals

⚠ Adverse Effects:

  • Headache, abdominal pain

  • Serious: MI, angina, stroke, TIA

  • Contraindicated in:

    • Moderate-severe renal or hepatic disease

    • Cardiovascular history

    • Women >65 y/o

🧠 Not a first-line drug due to serious risks.

👩‍⚕ 5. Prucalopride (Motegrity)

🔬 Class: Selective 5-HT₄ receptor agonist
⚙ Action:

  • Stimulates normal GI peristalsis

  • Used for chronic idiopathic constipation (CIC) in adults

🩺 Dosage:

  • 2 mg PO daily

⚠ Contraindications:

  • GI obstruction, ileus, perforation

  • Severe IBD (Crohn’s, UC)

  • Caution in kidney disease

😟 Adverse Effects:

  • Diarrhea, nausea, abdominal pain

  • Dizziness

  • Suicidal ideation reported — Monitor for depression

🧠 Use cautiously in mental health patients or those operating machinery

📊 Quick Comparison Table

Drug

Class

Main Use

Key Risks

Lactulose

Hyperosmotic sugar

Constipation + ↓ammonia

Electrolyte imbalance

Lubiprostone

Chloride channel activator

CIC, opioid-C, IBS-C (women only)

Nausea, dyspnea, syncope

Sorbitol

Hyperosmotic sugar alcohol

Constipation + used with Kayexalate/charcoal

Diarrhea, safe in pregnancy

Tegaserod

5-HT₄ agonist

IBS-C in women <65

CV events, avoid in renal/liver issues

Prucalopride

Selective 5-HT₄ agonist

CIC in adults

Suicidal ideation, GI disorders

✅ NCLEX-STYLE QUESTIONS + RATIONALES

Q1: Patient Safety

Which of the following medications is contraindicated in a female patient over 65 years old with a history of transient ischemic attack?

  • A. Lubiprostone

  • B. Prucalopride

  • C. Tegaserod

  • D. Lactulose

✅ Answer: C. Tegaserod
Rationale:

  • Contraindicated in women >65, and with TIA/stroke history

  • A: Safe in older women

  • B: Use with caution in kidney issues, but not specifically contraindicated

  • D: No CV risks

Q2: Drug Matching

Match the medication to its most appropriate indication:

  1. Lactulose

  2. Lubiprostone

  3. Sorbitol

  4. Prucalopride

A. Chronic idiopathic constipation in adults
B. Treatment of hepatic encephalopathy
C. Potassium removal and constipation prevention
D. IBS-C in women

✅ Answers:

  • 1 → B

  • 2 → D

  • 3 → C

  • 4 → A

Q3: Adverse Effect Monitoring

A patient on lubiprostone reports dizziness and shortness of breath within 2 hours of taking their first dose. What should the nurse do first?

  • A. Tell them to lie down and monitor BP

  • B. Tell them this is normal and will go away in 24 hours

  • C. Instruct them to take a second dose for relief

  • D. Recommend stopping the medication immediately

✅ Answer: A. Tell them to lie down and monitor BP
Rationale:

  • Acute dyspnea and hypotension are known effects — lie down, monitor vitals.

  • May resolve before next dose.

📌 FINAL REVIEW TIPS:

  • Lactulose:

    • Dual use: constipation + ↓ammonia

    • Traps NH₄⁺, lowers blood ammonia

  • Lubiprostone:

    • For women only with IBS-C

    • Cl⁻ channel → fluid secretion

    • SE: Nausea, dyspnea, hypotension

  • Sorbitol:

    • Given with Kayexalate or charcoal

    • Laxative + toxin remover

  • Tegaserod:

    • IBS-C in females <65

    • Contraindicated in CV disease, renal/hepatic issues

  • Prucalopride:

    • Good for CIC

    • Mental health risks: suicide ideation, dizziness