Generic Name

Lubiprostone

Mechanism

• Selective ClC‑2 activation → Chloride ions exit epithelium → Osmotic gradient drives water into the lumen
• Resulting in increased luminal fluid and esophageal churning without systemic prostaglandin effects
• No central nervous system penetration; no sedative or gastrointestinal motility‑inhibiting actions

Pharmacokinetics

• Route: Oral tablets
• Absorption: Limited; ~3 % oral bioavailability due to first‑pass metabolism
• Distribution: Low Vz (~20 L); negligible plasma protein binding
• Metabolism: Minimal hepatic oxidation; primarily excreted unchanged
• Elimination: Primarily fecal; 90 % excreted in stool, <10 % renal
• Half‑life: ~10–12 h (steady state reached after 3–5 days)

Indications

• Chronic Idiopathic Constipation (CIC) in adults (≥18 y)
• Irritable Bowel Syndrome with Constipation (IBS‑C) in adults
• Particularly useful when other laxatives fail or contraindicated

Contraindications

• Contraindications
• Severe hepatic or renal impairment (eGFR < 30 mL/min/1.73 m²)
• Metastatic cancers with significant GI obstruction
• Known hypersensitivity to prostaglandin analogues
• Warnings
• Pregnancy category C – use only if benefits outweigh risks
• Breastfeeding: potential passage into milk; avoid unless benefits justify
• Dysphagia or severe constipation with impaction—risk of excessive luminal fluid

Dosing

• Administration: Place tablet on tongue, allow to dissolve, or swallow whole with water
• Missed dose: Take as soon as remembered; skip if general 4‑h window passed

Adverse Effects

• Common (up to 10–15 %)
• Nausea, vomiting, abdominal pain, diarrhea, headache, sweating
• Serious (rare, <1 %)
• Severe dehydration (especially in prolonged use)
• Hypotension with significant fluid shifts
• Allergic reactions: rash, pruritus, angioedema

Monitoring

• Baseline assessment: electrolytes (Na⁺, K⁺, Cl⁻), serum glucose, liver function tests
• Follow‑up:
• Monitor hydration status (vital signs, urine output)
• Check for signs of dehydration or electrolyte disturbances after 1–2 weeks
• Evaluate stool frequency and consistency (Bristol Stool Form Scale)

Clinical Pearls

1. IBS‑C Savior – Lubiprostone is the only oral therapy explicitly approved for IBS‑C; it improves both pain and stool patterns.
2. Convenient BID – Despite a 12‑hr half‑life, the drug’s action is largely luminal; BID dosing sustains water retention in stool.
3. Rehydration Risk – Monitor patients with diabetes or CHF; excessive fluid in colon may precipitate the “intracolonic fluid overload” syndrome.
4. Drug Interactions – Minimal CYP interaction; may co‑administer with opioids or other laxatives on separate days to avoid excessive diarrhea.
5. Pregnancy & Lactation – Category C: if a patient becomes pregnant, consider discontinuation after first trimester unless benefit is compelling.

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