Peptide Schedule
Plecanatide (Trulance)16 residuesNDSCEICAFAACTGCLEach bubble = one amino acid. Size = residue mass. Color = chemical class.Plecanatide (Trulance)
Benefits
About Plecanatide (Trulance)
Plecanatide is a 16-amino-acid synthetic peptide and structural analog of human uroguanylin, the endogenous hormone that regulates fluid and electrolyte balance in the intestinal lumen. Developed by Salix/Bausch Health, it is the second guanylate cyclase-C (GC-C) agonist approved in the United States, following linaclotide. The FDA approved plecanatide for chronic idiopathic constipation (CIC) in adults in January 2017 and for irritable bowel syndrome with constipation (IBS-C) in adults in January 2018. Structurally, plecanatide differs from native uroguanylin by a single amino acid substitution: glutamic acid replaces aspartic acid at position 3. This modification preserves the two-disulfide-bond architecture (Cys4-Cys12 and Cys7-Cys15) and the pH-dependent activation profile that distinguishes it from linaclotide. Computational modeling has shown that plecanatide achieves its most active conformation at pH 5.0 — the pH of the proximal small intestine — where a stabilizing interaction forms between the negatively charged Glu3 side chain and the positively charged Asn9 in the binding loop. This pH-sensitive design means plecanatide preferentially activates GC-C receptors in the upper gut before reaching the colon, potentially contributing to its lower diarrhea rates compared to linaclotide. When plecanatide binds to GC-C on the luminal surface of intestinal epithelial cells, it triggers production of cyclic guanosine monophosphate (cGMP). Elevated intracellular cGMP activates the cystic fibrosis transmembrane conductance regulator (CFTR) ion channel, promoting secretion of chloride, bicarbonate, and water into the intestinal lumen. This hydrates stool, accelerates intestinal transit, and relieves constipation. Extracellular cGMP also acts on submucosal afferent pain neurons, reducing visceral hypersensitivity — the mechanism believed to account for the abdominal pain relief observed in IBS-C patients. Four pivotal Phase III trials established efficacy: two in CIC (NCT01982240, NCT02122471; combined n~2,600) and two in IBS-C (NCT02387359, NCT02493452; combined n~1,450). In CIC trials, durable overall complete spontaneous bowel movement (CSBM) responder rates were 20-21% for plecanatide 3 mg versus 10-13% for placebo (p < 0.005), with onset of effect within 24 hours of the first dose. In IBS-C trials, 30% of patients on plecanatide 3 mg met the combined FDA endpoint (simultaneous improvement in abdominal pain and stool frequency) versus approximately 18% on placebo. A notable pharmacokinetic feature is that plecanatide has negligible systemic absorption. Plasma concentrations remain below the limit of quantitation after oral dosing, so standard PK parameters (Cmax, AUC, t1/2) cannot be calculated. The drug acts entirely within the gastrointestinal lumen, where it is metabolized by loss of the C-terminal leucine residue to form an active 15-amino-acid metabolite that also binds GC-C.
Who Should Consider Plecanatide (Trulance)
- Adults with chronic idiopathic constipation (CIC) who have not responded adequately to lifestyle and dietary measures
- Adults with irritable bowel syndrome with constipation (IBS-C), particularly those with significant abdominal pain
- Patients who experienced intolerable diarrhea on linaclotide and need an alternative GC-C agonist with lower diarrhea rates
- Elderly patients (65+) with CIC or IBS-C — efficacy and safety are comparable to younger adults
- Patients on proton pump inhibitors or other acid-modifying medications (plecanatide is pH-dependent but not adversely affected by PPIs)
- Patients seeking a non-systemic, locally acting constipation therapy with minimal drug interaction potential
How Plecanatide (Trulance) Works
Plecanatide is a synthetic 16-amino-acid analog of human uroguanylin that acts as an agonist of guanylate cyclase-C (GC-C) receptors on the luminal surface of intestinal epithelial cells. Its mechanism proceeds through a well-characterized signaling cascade with two distinct therapeutic effects: secretory and analgesic. Upon binding to GC-C, plecanatide stimulates the intracellular production of cyclic guanosine monophosphate (cGMP). Elevated cGMP activates cGMP-dependent protein kinase II (PKGII), which phosphorylates and opens the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel at the apical membrane. This drives secretion of chloride and bicarbonate ions into the intestinal lumen, with water following osmotically. The resulting increase in luminal fluid hydrates stool, softens its consistency, and accelerates colonic transit — directly addressing the pathophysiology of constipation. Simultaneously, cGMP is transported extracellularly where it modulates submucosal afferent nerve signaling. This reduces visceral hypersensitivity, the heightened pain perception in the gut wall that is a hallmark of IBS-C. This dual mechanism — prokinetic and analgesic — distinguishes GC-C agonists from osmotic laxatives or stimulant laxatives that only address motility. The key structural feature that differentiates plecanatide from linaclotide is its pH-dependent activation. Plecanatide retains the two-disulfide-bond topology of native uroguanylin (Cys4-Cys12 and Cys7-Cys15), compared to linaclotide's three disulfide bonds derived from the E. coli heat-stable enterotoxin scaffold. The N-terminal acidic residues Asp2 and Glu3 function as pH sensors: at pH 5.0 (proximal small intestine), the Glu3 side chain forms a critical electrostatic interaction with Asn9 that locks the peptide into its maximally active conformation. At neutral to alkaline pH (distal gut), this interaction weakens, reducing receptor activation. Linaclotide, lacking this pH-sensing mechanism, activates GC-C uniformly throughout the entire intestine. This may explain why plecanatide produces lower rates of diarrhea (5% vs up to 19%) — it begins working in the proximal gut where fluid can be reabsorbed distally, rather than maximally stimulating secretion in the colon where absorption capacity is limited. After oral administration, plecanatide is proteolytically cleaved in the GI lumen, losing its C-terminal leucine to produce a 15-amino-acid active metabolite that retains GC-C agonist activity. Neither plecanatide nor its metabolite reaches measurable plasma concentrations at the therapeutic dose, confirming its action is entirely local.
What to Expect
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.
Dosing Protocol
| Level | Dose / Injection | Frequency |
|---|---|---|
| Beginner | 3mg | Daily |
| Moderate | 3mg | Daily |
| Aggressive | 3mg | Daily |
Note: Plecanatide (Trulance) is an FDA-approved oral tablet — no reconstitution or injection required. The only approved dose is 3 mg once daily by mouth, with or without food. Tablets may be crushed and mixed with applesauce or administered in water via a nasogastric or gastric feeding tube. There is no dose titration. All three dosing tiers are identical because 3 mg is the sole clinically validated dose; no benefit was observed with 6 mg over 3 mg in Phase III trials.
How to Inject Plecanatide (Trulance)
Plecanatide is supplied as 3 mg oral tablets in a bottle with desiccant. Take one 3 mg tablet by mouth once daily with or without food. Swallow tablets whole with water. Alternatively, tablets may be crushed and mixed with one teaspoon of room-temperature applesauce and swallowed immediately without chewing (do not store the mixture). For nasogastric or gastric feeding tube administration: crush the tablet, dissolve in 30 mL of room-temperature water, draw into a syringe, and administer within 10 minutes of preparation. Flush the tube with an additional 30 mL of water after dosing. There is no dose titration — the full therapeutic dose is 3 mg from day one. Store tablets in the original bottle with desiccant to protect from moisture; do not subdivide or repackage.
Cycling Protocol
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.
Pharmacokinetics
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.
Side Effects
Diarrhea is the most common adverse event, occurring in approximately 5% of plecanatide-treated patients versus 1% on placebo. Severe diarrhea was reported in 0.6% of patients (vs 0.3% placebo), with most cases occurring within the first four weeks of treatment and severe episodes typically within the first three days. Discontinuation due to adverse reactions occurred in 4% of patients (vs 2% placebo), with diarrhea being the most common reason. Other reported adverse events include abdominal distension, flatulence, abdominal tenderness, and sinusitis, though rates were similar to placebo. Carries a boxed warning regarding risk of serious dehydration in pediatric patients: contraindicated in patients under 6 years of age and should be avoided in patients 6 to under 18 years. In nonclinical studies, single oral doses caused mortality in young juvenile mice (postnatal days 7-14, human age equivalent approximately 1 month to under 2 years). Also contraindicated in patients with known or suspected mechanical gastrointestinal obstruction.
Contraindications
- Pediatric patients under 6 years of age (boxed warning — risk of serious dehydration)
- Pediatric patients aged 6 to under 18 years (should be avoided)
- Known or suspected mechanical gastrointestinal obstruction
- Known hypersensitivity to plecanatide or any excipient in the formulation
- Pregnancy — not studied in pregnant women; use only if clearly needed
- Breastfeeding — unknown whether plecanatide is excreted in human milk; negligible systemic absorption suggests low risk, but caution is advised
Drug Interactions
- No clinically significant interactions identified in clinical studies
- Does not inhibit CYP2C9 or CYP3A4 enzymes
- Does not induce CYP3A4
- No interaction with P-glycoprotein (P-gp) or breast cancer resistance protein (BCRP) transporters
- Negligible systemic absorption eliminates risk of pharmacokinetic drug interactions
Storage & Stability
Molecular Profile
Related Peptides
References
- A Randomized Phase III Clinical Trial of Plecanatide, a Uroguanylin Analog, in Patients With Chronic Idiopathic ConstipationPubMed 28169285
- Randomized clinical trial: efficacy and safety of plecanatide in the treatment of chronic idiopathic constipationPubMed 29147135
- Efficacy, safety, and tolerability of plecanatide in patients with irritable bowel syndrome with constipation: results of two phase 3 randomized clinical trialsPubMed 29545635
- Plecanatide (Trulance) for Chronic Idiopathic Constipation and Irritable Bowel Syndrome With ConstipationReview
- Therapeutically targeting guanylate cyclase-C: computational modeling of plecanatide, a uroguanylin analogPubMed 28357122
- Plecanatide: a new guanylate cyclase agonist for the treatment of chronic idiopathic constipationReview
- TRULANCE (plecanatide) tablets — Full Prescribing InformationFDA Label
- Efficacy and Tolerability of Guanylate Cyclase-C Agonists for IBS-C and CIC: A Systematic Review and Meta-AnalysisPubMed 29380823
- Phase 3 CIC Trial 1 (NCT01982240)Clinical Trial
- Phase 3 CIC Trial 2 (NCT02122471)Clinical Trial
- Phase 3 IBS-C Trial 1 (NCT02387359)Clinical Trial
- Phase 3 IBS-C Trial 2 (NCT02493452)Clinical Trial