Clarification: Lubiprostone and Amitiza Are the Same Medication
Lubiprostone and Amitiza are identical—Amitiza is simply the brand name for lubiprostone, so there is no choice to be made between them. 1
Understanding the Question
Your question appears to ask about choosing between two options that are actually the same drug. The term "PAMORA" (Peripherally Acting Mu-Opioid Receptor Antagonist) in your question is also technically incorrect, as lubiprostone is not a PAMORA—it is a chloride channel-2 activator that works through an entirely different mechanism. 2, 1
Correct Clinical Context
If you are asking about initiating secretagogue therapy (not PAMORA therapy) after failure of two laxatives in a patient with chronic constipation or IBS-C, lubiprostone/Amitiza is one reasonable option among several secretagogues.
Dosing Based on Indication
The critical distinction is using the correct dose for the specific diagnosis: 1
- For Chronic Idiopathic Constipation (CIC): 24 mcg twice daily 1
- For IBS-C in women ≥18 years: 8 mcg twice daily 1
- For Opioid-Induced Constipation (OIC): 24 mcg twice daily 1
Evidence for Lubiprostone Use
The AGA conditionally recommends lubiprostone for patients with IBS-C who have failed initial therapies, based on moderate-quality evidence. 2
- Lubiprostone demonstrated superiority over placebo for modified FDA response (adequate abdominal pain and spontaneous bowel movement response; RR 0.88,95% CI 0.79-0.96) in two phase 3 RCTs involving 1,154 IBS-C patients 2
- It improved global response (RR 0.93,95% CI 0.87-0.96) and abdominal pain relief (RR 0.85,95% CI 0.76-0.95) 2
- However, it did NOT significantly improve spontaneous bowel movement frequency alone (RR 0.90,95% CI 0.75-1.10) 2
Administration and Safety Considerations
Always administer lubiprostone with food and water to minimize nausea, the most common adverse effect. 3, 1
- Nausea occurs in up to 35% of patients but is typically mild-to-moderate and dose-dependent 3
- Only approximately 5% discontinue due to nausea 3
- Gastrointestinal adverse events occurred in 19% on lubiprostone versus 14% on placebo 2
- Discontinuation rates due to adverse events were similar between lubiprostone (12.8%) and placebo (12.3%) 2
Dose Adjustments for Hepatic Impairment
Patients with moderate-to-severe hepatic impairment require dose reduction: 1
- Moderate impairment (Child-Pugh B): 16 mcg twice daily for CIC/OIC; no adjustment for IBS-C 1
- Severe impairment (Child-Pugh C): 8 mcg twice daily for CIC/OIC; 8 mcg once daily for IBS-C 1
Clinical Positioning
Lubiprostone is suggested for adults with chronic constipation who do not respond to over-the-counter agents and can be used as replacement or adjunct therapy. 3, 4
- Effects typically manifest within 2 days in responders 3
- Long-term safety data support tolerability for up to 13 months 2
- For IBS-C specifically, it is FDA-approved only for women ≥18 years old 1
Important Contraindications
Lubiprostone is contraindicated in patients with known or suspected mechanical gastrointestinal obstruction. 1