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Plecanatide (Trulance)16 residuesNDSCEICAFAACTGCLEach bubble = one amino acid. Size = residue mass. Color = chemical class.Also known as: Trulance, SP-304
Five percent diarrhea versus nineteen percent. That single number is why plecanatide exists. This FDA-approved GC-C agonist (brand name Trulance) treats chronic idiopathic constipation and irritable bowel syndrome with constipation in adults using one 3 mg oral tablet daily. Four Phase 3 trials across 4,000+ patients confirmed it works, though the benefit is modest: roughly 20% of patients meet durable response criteria versus 10% on placebo. The people who get the most from it are linaclotide switchers chasing lower GI side effects. No injection, no reconstitution, no food timing restrictions.
Does switching from Linzess to Trulance actually cut diarrhea by two-thirds? The Phase 3 data says yes. Plecanatide (CAS 467426-54-6), a 16-amino-acid synthetic analog of human uroguanylin, received FDA approval for chronic idiopathic constipation in January 2017 and for IBS-C in January 2018. The mechanism is specific. Plecanatide binds GC-C receptors on intestinal epithelial cells, triggering cyclic GMP production. That cGMP opens CFTR chloride channels, pulling water into the gut lumen. Stool softens; transit speeds up. A second effect matters for IBS-C patients: extracellular cGMP dials down visceral hypersensitivity through submucosal afferent nerve modulation. The difference between plecanatide and linaclotide comes down to pH sensitivity. Plecanatide activates primarily at pH 5.0 in the proximal small intestine, then quiets down in the distal gut. Linaclotide fires uniformly throughout. That targeted activation likely explains the diarrhea gap (5% vs up to 19% in trials by Miner and colleagues)[1]. Four Phase 3 trials tell the efficacy story. In CIC (combined n of roughly 2,600), durable CSBM responder rates hit 20 to 21% versus 10 to 13% on placebo. In IBS-C (pooled n of 1,455), 25.6% met the FDA composite endpoint versus 16.0% on placebo (Brenner and colleagues)[2]. Those numbers are modest in absolute terms. About 80% of CIC patients won't meet the strict durable responder definition. Cost compounds the frustration: retail pricing runs $728 to $829 per month without insurance.
Plecanatide copies the structure of uroguanylin, the body's own hormone for regulating intestinal fluid balance. The synthetic version differs by a single amino acid: glutamic acid replaces aspartic acid at position 3. When the tablet dissolves and reaches the proximal small intestine, plecanatide binds to guanylate cyclase-C receptors on the luminal surface of epithelial cells. This triggers a signaling cascade. Intracellular cGMP rises. cGMP-dependent protein kinase II phosphorylates the CFTR chloride channel at the cell surface. Chloride and bicarbonate flow into the intestinal lumen; water follows by osmosis. The result is softer stool and faster transit. A second pathway runs in parallel. cGMP leaves the cell and acts on submucosal afferent pain neurons. This reduces visceral hypersensitivity, the amplified gut pain perception that defines IBS-C. Osmotic laxatives and stimulant laxatives don't touch this pathway; GC-C agonists do. The pH-sensing design is what separates plecanatide from linaclotide. Computational modeling by Shailubhai and colleagues [3] showed that at pH 5.0, the Glu3 side chain locks into an electrostatic interaction with Asn9. This stabilizes the active conformation. At neutral pH in the distal gut, that interaction weakens and receptor activation drops off. Linaclotide's three-disulfide-bond scaffold (derived from E. coli heat-stable enterotoxin) lacks this pH switch entirely. The clinical consequence: less secretory activity in the colon, where reabsorption capacity is limited, which likely drives the lower diarrhea rate. Neither plecanatide nor its active 15-amino-acid metabolite reaches measurable plasma concentrations at the 3 mg dose. The drug acts entirely within the GI lumen.
FDA-approved GC-C agonist with strong trial evidence for CIC and IBS-C. Single fixed dose (3 mg PO daily). Efficacy is modest (~20% above-placebo CSBM responder rate in CIC; pooled IBS-C responder rate 25.6% vs 16.0% placebo). Negligible systemic absorption; safety profile well-characterized in 4,000+ trial patients.
PMID 28169285 (CIC Trial 1, n=1,346): 21.0% vs 10.2% placebo CSBM durable responder rate (p<0.0001); PMID 29545635 (IBS-C pooled, n=1,455): 25.6% vs 16.0% placebo combined responder rate (p<0.001)
No head-to-head trial vs linaclotide. IBS-C responder rates differ substantially between Trial 1 (21.5%) and Trial 2 (30.2%); pooled result (25.6%) is the most representative estimate. Phase 3 trials ran only 12 weeks. No pediatric efficacy/safety data for ages 6–17.
Mixed. Most users are switchers from linaclotide (Linzess) seeking lower diarrhea rates. Diarrhea reduction vs linaclotide is consistently confirmed. Efficacy for constipation is perceived and similar to Linzess. High out-of-pocket cost is the dominant complaint.
Community experience closely mirrors clinical trial outcomes: modest efficacy (~20% above placebo), lower diarrhea vs linaclotide, rapid onset. Community primarily uses this drug exactly: no off-label dosing or stacking attempts documented.
| Level | Dose / Injection | Frequency |
|---|---|---|
| Beginner | 3mg | Daily |
| Moderate | 3mg | Daily |
| Aggressive | 3mg | Daily |
Trulance is an oral tablet. No vials, no bacteriostatic water, no syringes. That alone sets it apart from most peptides on this site. The dose is 3 mg once daily by mouth. Take it whenever is convenient; there's no food restriction and no timing requirement. Swallow the tablet whole with water. If swallowing pills is an issue, you can crush the tablet and mix it with one teaspoon of room-temperature applesauce. Swallow immediately without chewing. Don't store the mixture. For tube feeding: crush the tablet, dissolve in 30 mL of room-temperature water, draw into a syringe, and administer within 10 minutes. Flush the tube with 30 mL water afterward. One thing beginners often miss: give it a real trial period. The strict durable responder definition requires weeks of consistent improvement. Evaluating at day 3 or 4 misses the point. Allow 2 to 4 weeks before deciding if it's working. If you're switching from Linzess because of diarrhea (the most common reason people switch), the diarrhea improvement is typically obvious within the first week. Store tablets in the original bottle with the desiccant cap. Moisture is the enemy.
Intended for continuous daily use. Phase III trials established efficacy over 12-week treatment periods. No cycling or drug holidays are recommended in the prescribing information. Reassess if symptoms resolve completely, as some patients may not require indefinite therapy.
Plecanatide is labeled for continuous daily use with no cycling requirement. GC-C receptors are locally expressed in the gut and do not undergo systemic desensitization at the 3 mg dose. Phase 3 trials ran 12 weeks without efficacy attenuation. Prescribing information does not specify a maximum treatment duration and recommends periodic clinical reassessment rather than structured drug holidays.
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Expected: Durable CSBM responder rate ~20–21% vs 10–13% placebo at 12 weeks (PMID 28169285, 29147135). Onset within 24 hours of first dose. ~79–80% of patients do not meet the durable responder endpoint.
Monitor: Assess symptom response at 2–4 weeks. Monitor for diarrhea severity in first 4 weeks (severe diarrhea occurred in 0.6% vs 0.3% placebo). No laboratory monitoring required.
Replace the cap immediately to protect remaining tablets from moisture.
No need to time around meals.
If you cannot swallow the tablet whole: crush one tablet and mix thoroughly with one teaspoon (approximately 5 mL) of room-temperature applesauce. Swallow the entire mixture immediately. Do not chew. Do not save any portion for later.
For nasogastric or gastric tube administration: crush one tablet and dissolve in 30 mL of room-temperature water. Draw into a catheter-tip syringe. Administer within 10 minutes of preparation. Flush the tube with an additional 30 mL of water.
Take once daily at the same general time each day for consistency. Morning is the most common choice per community reports.
The 3 mg dose is therapeutic from day one.
Store the bottle at room temperature (20 to 25 degrees Celsius). Keep the desiccant inside. Do not transfer tablets to a pill organizer or other container.
None: 3 mg tablet is the reference formulation
Swallow whole with water. No food restriction. No timing restriction.
None: same 3 mg dose
Crush 1 tablet, mix with 1 tsp room-temperature applesauce, swallow immediately without chewing. Do NOT store mixture.
None: same 3 mg dose
Crush tablet, dissolve in 30 mL room-temperature water, draw into syringe, administer within 10 minutes. Flush tube with 30 mL water post-dose.
Used by some GI clinicians for IBS-C patients whose abdominal pain component is inadequately controlled by plecanatide alone. TCAs have independent visceral analgesic effects via norepinephrine reuptake inhibition. Off-label combination.
Low-dose TCA (10–25 mg nightly) added by prescriber when pain persists despite plecanatide response
Clinically combined in patients with comorbid GERD or functional dyspepsia. No pharmacokinetic interaction (negligible systemic absorption of plecanatide). Addresses overlapping upper and lower GI symptoms.
Redundant GC-C agonist mechanism with additive diarrhea risk. No clinical rationale for combination. Patients who fail plecanatide should switch to an alternative mechanism (e.g., lubiprostone, tenapanor), not add linaclotide.
Do not combinePricing updated 2026-04-09
Plecanatide carries a boxed warning for pediatric patients. In nonclinical studies, single oral doses caused death in young juvenile mice (postnatal days 7 to 14, roughly equivalent to human infants under 2 years). The drug is contraindicated in children under 6 and should be avoided in patients aged 6 to under 18. For adults, the safety profile across 4,000+ Phase 3 participants is well characterized. Diarrhea is the primary adverse event, reported in approximately 5% of plecanatide-treated patients versus 1% on placebo. Severe diarrhea occurred in 0.6% of patients (versus 0.3% placebo). The timing matters: most diarrhea cases appeared within the first four weeks of treatment. Severe episodes clustered in the first three days. If you're going to have trouble with diarrhea, you'll know quickly. Treatment discontinuation due to adverse reactions occurred in 4% of patients compared to 2% on placebo. Diarrhea was the most common reason for stopping. Other reported adverse events included abdominal distension, flatulence, abdominal tenderness, and sinusitis. Rates for these were similar to placebo, so causation is uncertain. The negligible systemic absorption provides a measure of reassurance. Plasma concentrations remain below the limit of quantitation at the 3 mg dose. This means the list of potential systemic side effects is short; essentially, the drug stays in the gut. Contraindications beyond the pediatric warning: known or suspected mechanical gastrointestinal obstruction, and hypersensitivity to plecanatide or any excipient. Pregnancy has not been studied; the FDA label advises use only if clearly needed. Whether plecanatide appears in breast milk is unknown, though negligible absorption suggests low risk. There is no dose reduction option. The 3 mg tablet is the sole approved dose. If diarrhea is intolerable, the only path is discontinuation. The 6 mg dose was tested in Phase 3 and showed no additional benefit while increasing diarrhea risk, so exceeding 3 mg is not recommended either. When to contact your prescriber: severe or persistent diarrhea, signs of dehydration (dizziness, reduced urination, dry mouth), or new abdominal pain that feels different from your baseline symptoms.
Verify Plecanatide (Trulance) dosing and safety with a second opinion
FDA-approved branded pharmaceutical (Trulance, Bausch Health/Salix) manufactured under cGMP. Dispensed through licensed US pharmacies only. No compounded versions in clinical or community use. Oral formulation eliminates injection-related contamination risk. Negligible systemic absorption further limits adverse event potential.
| Test | When | Target |
|---|---|---|
| Clinical symptom assessment (CSBM frequency, stool consistency, abdominal pain score) | At 2–4 weeks, then at 12 weeks | CIC: ≥1 additional CSBM/week vs baseline for ≥9 of 12 treatment weeks. IBS-C: simultaneous improvement in abdominal pain and stool frequency meeting FDA composite endpoint. |
| Diarrhea severity assessment | Days 1–7 (highest risk window), then indicated | Diarrhea in 5% of patients; severe diarrhea 0.6%: both substantially lower than linaclotide. |
Primary efficacy endpoint: durable CSBM response requires consistent improvement across multiple weeks. IBS-C responder definition requires simultaneous pain + frequency improvement.
Severe diarrhea (with dehydration) warrants discontinuation per FDA label. Most severe cases occur in first 3 days.
First dose at full therapeutic strength (3 mg). Many patients experience a bowel movement within 24 hours. Initial GI effects such as mild bloating or loose stools may occur as intestinal fluid secretion increases.
Stool frequency and consistency begin to normalize. If severe diarrhea occurs, it most commonly appears within the first 3 days: contact prescriber if significant. Most patients notice meaningful improvement in spontaneous bowel movement frequency by end of the first week.
Sustained improvement in CSBM frequency, stool consistency, and straining. Abdominal pain and bloating in IBS-C patients begin to improve. Any initial diarrhea typically resolves. If diarrhea persists beyond 4 weeks, reassess.
Full therapeutic benefit established. Durable CSBM responder rates of approximately 20% (vs 10% placebo) in CIC. Combined abdominal pain and bowel function responder rates of 30% (vs 18% placebo) in IBS-C. Effects are maintained throughout the treatment period.
Long-term use is generally well tolerated. Prescribing information supports continued use. Reassess periodically to determine if ongoing therapy is needed, as some patients may achieve sustained improvement that persists after discontinuation.
Day 1: The first 3 mg tablet delivers the full therapeutic dose. GC-C activation triggers chloride and water secretion within hours. Many patients have a bowel movement within 24 hours. Mild cramping, urgency, or loose stools can show up on day one. Days 2 to 7: Stool frequency and consistency start evening out. Severe diarrhea, if it's going to happen, usually hits within the first 3 days. Patients who get through the first week without diarrhea issues tend to tolerate the drug well going forward. Weeks 2 to 4: The improvement pattern stabilizes. Bowel habits reach a new baseline. IBS-C patients begin noticing abdominal pain relief as the cGMP-mediated analgesic effect builds. Any early diarrhea typically resolves by week 4. If diarrhea persists past this point, reassess with your prescriber. Weeks 4 to 12: Full therapeutic benefit is established. The Phase 3 endpoints were measured at 12 weeks: durable CSBM responder rates of 20 to 21% in CIC and 25.6% pooled in IBS-C. No tachyphylaxis or dose escalation requirement was seen through 12 weeks. Interestingly, long-term users report that cost, not efficacy failure, is the main reason people stop. Beyond 12 weeks: The FDA label supports continuous daily use with no maximum duration. No tolerance development has been documented. Periodic reassessment is reasonable; some patients may achieve lasting improvement that persists after stopping.
GC-C activation drives chloride and bicarbonate secretion within hours. Onset of first spontaneous bowel movement within 24 hours in Phase 3 trials (statistically significant vs placebo from Week 1).
Many users report a bowel movement the same day or next morning. Some report mild cramping or urgency. Community expectation of rapid onset is generally confirmed.
Stool frequency and consistency begin to normalize. Severe diarrhea, if it occurs, most commonly appears within the first 3 days.
Most users know within the first week whether they will experience diarrhea issues. Those without diarrhea report steady improvement in stool consistency.
Durable CSBM frequency established. IBS-C abdominal pain scores begin to improve. Initial diarrhea typically resolves by week 4.
Users who tolerate the first week tend to stay on therapy. Abdominal pain reduction in IBS-C noted in this window. Some users describe improvement vs initial expectations.
Durable CSBM responder rates: 20–21% (CIC) and 25.6% pooled (IBS-C). No tachyphylaxis or dose escalation requirement documented through 12 weeks.
Long-term users report stable bowel function. High discontinuation driven by cost rather than efficacy failure. Perceived modestly for constipation; more noticeable for pain in IBS-C.
Label supports indefinite use. No tolerance or dose escalation requirement. Periodic clinical reassessment recommended.
Insurance coverage and cost are primary drivers of long-term discontinuation. Patients who restart after coverage gaps report consistent re-response.
Source: FDA label: plasma concentrations below limit of quantitation at 3 mg oral dose; standard PK parameters (t1/2, Cmax, AUC) cannot be calculated due to negligible systemic absorption
Loading the interactive decay curve.
Plecanatide is FDA-approved and marketed as Trulance by Bausch Health (Salix Pharmaceuticals). FDA approval dates: January 2017 for chronic idiopathic constipation in adults, January 2018 for irritable bowel syndrome with constipation in adults. Trulance is a prescription medication dispensed through licensed US pharmacies. No compounded versions are in clinical or community use. It is not available as a research chemical or through grey-market peptide suppliers. WADA status is not applicable; plecanatide has no performance-improving properties and is not on the prohibited list. No generic version is currently available. The branded product is the sole option. Manufacturer savings cards at trulance.com/savings may reduce costs to as low as $25 per month for eligible commercially insured patients. GoodRx coupons bring uninsured pricing from roughly $829 to approximately $547 per month. This content is for informational purposes only and does not constitute medical advice. Consult a licensed healthcare provider before starting or changing any medication.
Peptide Schedule Research TeamReviewed Apr 202612 Citations
