Plecanatide

• Chronic Idiopathic Constipation
• Irritable Bowel Syndrome with Constipation
• Functional Constipation

Plecanatide (brand name Trulance) is a guanylate cyclase-C (GC-C) agonist taken once daily for chronic idiopathic constipation and irritable bowel syndrome with constipation in adults. It is structurally similar to the body's own intestinal peptide uroguanylin and works locally on the lining of the small intestine to draw fluid into the bowel lumen, soften stool, and accelerate transit. Because virtually none of the drug enters the bloodstream, plecanatide has minimal systemic side effects and few drug interactions, making it a useful option for patients who have not responded adequately to fiber, osmotic laxatives, or stimulant laxatives. It is taken once a day with no titration, and most patients see meaningful change in bowel habit within the first few days to two weeks of consistent use.

Mechanism of Action

Guanylate cyclase-C is a membrane-bound enzyme expressed on the apical (luminal) surface of intestinal epithelial cells throughout the small bowel. The body's natural ligands - guanylin and uroguanylin - bind GC-C to regulate intestinal fluid balance. Plecanatide is a 16-amino-acid synthetic analog of uroguanylin that binds the same receptor with high affinity. Receptor activation increases intracellular cyclic guanosine monophosphate (cGMP), which then activates the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel on the cell surface.

Opening CFTR drives chloride and bicarbonate secretion into the intestinal lumen, with sodium and water following osmotically. The net result is increased luminal fluid volume, softer stool, and faster transit through the colon. Some of the increased cGMP also escapes the basolateral surface of the cell, where it appears to modulate visceral pain pathways - which may explain the abdominal pain and discomfort improvements seen in IBS-C trials beyond simple bowel frequency increases. Unlike its sister molecule linaclotide, plecanatide is pH-sensitive and most active in the slightly acidic proximal small intestine, which the manufacturer cites as the basis for somewhat lower diarrhea rates. Plecanatide and its active metabolite are not detectable in plasma at therapeutic doses, which means the drug essentially never produces systemic effects, regardless of patient comorbidities or co-prescribed medications. The full prescribing information and safety summary are available through DailyMed and patient education on functional bowel disorders is available from the National Institute of Diabetes and Digestive and Kidney Diseases.

Clinical Use

For chronic idiopathic constipation, plecanatide is positioned as a second-line therapy after lifestyle adjustments, fiber, and over-the-counter osmotic agents like polyethylene glycol fail to provide adequate relief. Comparable prescription options include linaclotide, lubiprostone, prucalopride, and tegaserod for women under 65. Head-to-head data among these agents are limited, but plecanatide and linaclotide are similarly effective on bowel frequency and stool form, with plecanatide often described as having a slightly more tolerable diarrhea profile. The American College of Gastroenterology and the American Gastroenterological Association recommend any of the GC-C agonists, lubiprostone, or prucalopride as appropriate prescription choices when over-the-counter therapy fails.

For irritable bowel syndrome with constipation, plecanatide is FDA-approved and improves both stool frequency and abdominal pain compared with placebo. Patient selection favors adults with infrequent bowel movements (fewer than three per week), straining, hard or lumpy stools, and a sense of incomplete evacuation despite fiber and osmotic therapy. It is contraindicated in patients under 6 years and avoided between ages 6 and 18 because juvenile animal studies showed serious dehydration risk. Plecanatide should not be used in known or suspected mechanical bowel obstruction. Patients with significant baseline diarrhea, fragile fluid status, recent gastrointestinal surgery, or severe pelvic floor dysfunction may not be appropriate candidates. For patients whose constipation is largely behavioral or due to slow transit without alarm features, dietary and lifestyle approaches such as those described in our article on how digestive health impacts everything should be reinforced before or alongside drug therapy. A careful medication review at every visit identifies common offenders such as opioids, anticholinergics, calcium-channel blockers, and iron supplements that may be driving the symptom.

How to Take It

The dose is one 3 mg tablet once daily, taken at any time of day, with or without food. Most patients pick a consistent time - often morning - to anchor the routine. The tablet may be swallowed whole or, for patients with swallowing difficulty, crushed and mixed with one teaspoon of room-temperature applesauce and consumed immediately, or dispersed in 30 mL of water, swirled briefly, and drunk at once with no chewing of the residual tablet fragments. Crushed doses are not stored for later use.

If a dose is missed, take it as soon as remembered the same day, but skip if it is the following day - never double up. Some patients see a softer bowel movement within 24 to 48 hours; full benefit on stool form, frequency, and abdominal symptoms typically emerges over two to four weeks. The first week may bring loose stools, urgency, and mild bloating as the bowel adjusts; these usually settle. Adequate water intake supports the drug's effect and reduces the risk of dehydration if diarrhea occurs. Store tablets in the original sealed bottle with the desiccant intact, at room temperature. Patients should be advised to discontinue temporarily and contact the office if diarrhea is severe or causes lightheadedness or weakness; reintroduction at every-other-day dosing is sometimes successful before returning to daily dosing. The drug should not be used as a rescue or as-needed laxative; its effect is built up with consistent daily dosing.

Monitoring and Follow-Up

No routine laboratory monitoring is required for plecanatide because systemic absorption is negligible. Clinical follow-up at four to six weeks reviews bowel frequency, stool consistency using the Bristol Stool Scale, abdominal pain or bloating, and any diarrhea or dehydration symptoms. Patients are asked specifically about lightheadedness on standing, decreased urine output, or unintended weight loss, which can suggest fluid loss requiring dose interruption. A symptom diary covering bowel movements, stool form, and pain in the first month is useful for both patient and clinician to gauge true response.

If the patient reports persistent diarrhea, the most common course is brief discontinuation followed by reintroduction every other day, then daily once tolerated. Persistent inadequate response after eight to twelve weeks of consistent daily use suggests trying a different mechanism - lubiprostone, prucalopride, or osmotic therapy. Annual review of the indication is reasonable; some patients can take periodic breaks once a regular bowel pattern is established. New onset of red-flag features - rectal bleeding, weight loss, anemia, family history of colon cancer, age greater than 50 without prior screening - prompts age-appropriate colorectal evaluation regardless of plecanatide use. Concurrent calcium and iron supplements, opioid analgesics, and anticholinergic medications should be reviewed at each visit because they can blunt the drug's effect, and adherence should be assessed honestly because intermittent use rarely produces the steady response patients seek.

Special Populations

Plecanatide is contraindicated in patients under 6 years of age because of fatal dehydration in juvenile animal studies, and is not recommended between 6 and 18 years because safety has not been established. In elderly patients, no dose adjustment is required, but vigilance for dehydration is heightened, particularly in those on diuretics or with baseline fragility. No dose adjustment is necessary for renal impairment because elimination is largely fecal and absorption negligible. No adjustment is needed for hepatic impairment for the same reason.

Pregnancy data are limited; animal studies showed no fetal harm at doses far above human exposure, and use during pregnancy is acceptable when needed. Lactation effects are not characterized but expected to be minimal given negligible systemic absorption. Drug interactions are essentially absent; patients taking warfarin, antiepileptics, or other narrow-therapeutic-index drugs do not require dose adjustment. Patients with diabetic gastroparesis, scleroderma-associated dysmotility, or postsurgical pseudo-obstruction should be approached cautiously because GC-C agonist effects are limited when the dominant problem is impaired motility rather than secretion. Combination of plecanatide with other prescription constipation agents has not been formally studied and is generally avoided; patients failing one agent are typically switched rather than combined.

When to Contact Your Doctor

Call the office for severe diarrhea, particularly if accompanied by lightheadedness, decreased urine output, weakness, or weight loss, as dehydration can develop quickly. Persistent abdominal pain that is severe or worsening, especially with vomiting or absence of bowel movements, may suggest obstruction and requires urgent evaluation. Rectal bleeding, black or tarry stools, unintentional weight loss, fevers, or new abdominal mass should be reported promptly. Allergic reaction signs including rash, hives, swelling, or difficulty breathing warrant emergency care. If your bowel pattern does not improve after one to two months of consistent use, schedule a follow-up to reassess the diagnosis and treatment plan.

If you would like to discuss whether plecanatide is the right next step for your constipation symptoms, contact us or schedule a visit with our internal medicine team.