Plecanatide

12.1 Mechanism of Action Plecanatide is a structural analog of human uroguanylin, and similarly to uroguanylin, plecanatide functions as a guanylate cyclase-C (GC-C) agonist. Both plecanatide and its active metabolite bind to GC-C and act locally on the luminal surface of the intestinal epithelium. Activation of GC-C results in an increase in both intracellular and extracellular concentrations of cyclic guanosine monophosphate (cGMP). Elevation of extracellular cGMP has been associated with a decrease in the activity of pain-sensing nerves in animal models of visceral pain. Elevation of intracellular cGMP stimulates secretion of chloride and bicarbonate into the intestinal lumen, mainly through activation of the cystic fibrosis transmembrane conductance regulator (CFTR) ion channel, resulting in increased intestinal fluid and accelerated transit. In animal models, plecanatide has been shown to increase fluid secretion into the gastrointestinal (GI) tract, accelerate intestinal transit, and cause changes in stool consistency. In an animal model of visceral pain, plecanatide reduced abdominal muscle contractions, a measure of intestinal pain.

1 INDICATIONS AND USAGE TRULANCE is indicated in adults for the treatment of: chronic idiopathic constipation (CIC). irritable bowel syndrome with constipation (IBS-C). TRULANCE is a guanylate cyclase-C agonist indicated in adults for treatment of: chronic idiopathic constipation (CIC). ( 1 ) irritable bowel syndrome with constipation (IBS-C). ( 1 )

2 DOSAGE AND ADMINISTRATION The recommended adult dosage of TRULANCE is CIC: 3 mg taken orally once daily. ( 2.1 ) IBS-C: 3 mg taken orally once daily. ( 2.1 ) Administration Instructions ( 2.2 ): Take with or without food. Swallow tablets whole. For patients who have difficulty swallowing tablets whole or those with a nasogastric or gastric feeding tube, see full prescribing information with instructions for crushing the tablet and administering with applesauce or water. 2.1 Recommended Dosage The recommended dosage of TRULANCE for the treatment of CIC and IBS-C is 3 mg taken orally once daily. 2.2 Preparation and Administration Instructions Take TRULANCE with or without food [see Clinical Pharmacology (12.3) ] . If a dose is missed, skip the missed dose and take the next dose at the regular time. Do not take two doses at the same time. Swallow a tablet whole for each dose. For adult patients with swallowing difficulties, TRULANCE tablets can be crushed and administered orally either in applesauce or with water or administered with water via a nasogastric or gastric feeding tube. Mixing TRULANCE crushed tablets in other soft foods or in other liquids has not been tested. Oral Administration in Applesauce: In a clean container, crush the TRULANCE tablet to a powder and mix with 1 teaspoonful of room temperature applesauce. Consume the entire tablet-applesauce mixture immediately. Do not store the mixture for later use. Oral Administration in Water: Place the TRULANCE tablet in a clean cup. Pour approximately 30 mL of room temperature water into the cup. Mix by gently swirling the tablet and water mixture for at least 10 seconds. The TRULANCE tablet will fall apart in the water. Swallow the entire contents of the tablet-water mixture immediately. If any portion of the tablet is left in the cup, add another 30 mL of water to the cup, swirl for at least 10 seconds, and swallow immediately. Do not store the tablet-water mixture for later use. Administration with Water via a Nasogastric or Gastric Feeding Tube: Place the TRULANCE tablet in a clean cup with 30 mL of room temperature water. Mix by gently swirling the tablet and water mixture for at least 15 seconds. The TRULANCE tablet will fall apart in the water. Flush the nasogastric or gastric feeding tube with 30 mL of water using a catheter tip syringe. Draw up the mixture using the syringe and immediately administer via the nasogastric or gastric feeding tube. Do not reserve for future use. If any portion of the tablet is left in the cup, add another 30 mL of water to the cup, swirl for at least 15 seconds, and using the same syringe, administer via the nasogastric or gastric feeding tube. Using the same or a fresh syringe, flush the nasogastric or gastric feeding tube with at least 10 mL of water.

6 ADVERSE REACTIONS Most common adverse reaction (≥2%) is diarrhea. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Salix Pharmaceuticals at 1-800-321-4576 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in practice. Demographic characteristics were comparable between the TRULANCE and placebo groups in all studies [see Clinical Studies (14) ] . Chronic Idiopathic Constipation (CIC) The safety data described below reflect data from 1,733 adult patients with CIC randomized in two double-blind, placebo-controlled clinical trials (Study 1 and Study 2) to receive placebo or 3 mg of TRULANCE once daily for 12 weeks. Most Common Adverse Reactions Table 1 provides the incidence of adverse reactions reported in at least 2% of CIC patients in the TRULANCE-treated group and at an incidence that was greater than in the placebo group. Table 1: Most Common Adverse Reactions a in Two Placebo-Controlled Trials of TRULANCE [Study 1 and Study 2] in Patients with CIC Adverse Reaction TRULANCE, 3 mg (N = 863) % Placebo (N = 870) % a: Reported in at least 2% of TRULANCE-treated patients with CIC and at an incidence greater than placebo. b: Verbatim reports of diarrhea were recorded as adverse reactions; reports of loose stools and increase in stool frequency were recorded as adverse reactions if they were also reported to be bothersome to the patient. Diarrheaᵇ 5 1 Diarrhea The majority of reported cases of diarrhea occurred within 4 weeks of treatment initiation. Severe diarrhea was reported in 0.6% of TRULANCE-treated patients compared to 0.3% of placebo-treated patients. Severe diarrhea was reported to occur within the first 3 days of treatment [see Warnings and Precautions (5.2) ] . Adverse Reactions Leading to Discontinuation Discontinuations due to adverse reactions occurred in 4% of TRULANCE-treated patients and 2% of placebo-treated patients. The most common adverse reaction leading to discontinuation was diarrhea: 2% of TRULANCE-treated patients and 0.5% of placebo-treated patients withdrew due to diarrhea . Less Common Adverse Reactions Adverse reactions reported in less than 2% of TRULANCE-treated patients and at an incidence greater than placebo were: sinusitis, upper respiratory tract infection, abdominal distension, flatulence, abdominal tenderness, and increased liver biochemical tests (2 patients with alanine aminotransferase (ALT) greater than 5 to 15 times the upper limit of normal and 3 patients with aspartate aminotransferase (AST) greater than 5 times the upper limit of normal). Irritable Bowel Syndrome with Constipation (IBS-C) The safety data described below reflect data from 1,449 adults patients with IBS-C randomized in two double-blind, placebo-controlled clinical trials (Study 3 and Study 4) to receive placebo or 3 mg TRULANCE once daily for 12 weeks. Most Common Adverse Reactions Table 2 provides the incidence of adverse reactions reported in at least 2% of IBS-C patients treated with TRULANCE and at an incidence that was greater than in the placebo group. Table 2: Most Common Adverse Reactions a in Two Placebo-Controlled Trials of TRULANCE [Study 3 and Study 4] in Patients with IBS-C Adverse Reaction TRULANCE, 3 mg (N = 723) % Placebo (N = 726) % a: Reported in at least 2% of TRULANCE-treated patients with IBS-C and at an incidence greater than placebo. b: Verbatim reports of diarrhea were recorded as adverse reactions; reports of loose stools and increase in stool frequency were recorded as adverse reactions if they were also reported to be bothersome to the patient. Diarrhea b 4.3 1 Diarrhea The majority of reported cases of diarrhea occurred within 4 weeks of treatment initiation. Severe diarrhea was reported in 1% of TRULANCE-treated patients compared to 0.1% of placebo-treated patients [see Warnings and Precautions (5.2) ] . Severe diarrhea was reported to occur within the first day of treatment. Adverse Reactions Leading to Discontinuation Discontinuations due to adverse reactions occurred in 2.5% of TRULANCE-treated patients and 0.4% of placebo-treated patients. The most common adverse reaction leading to discontinuation was diarrhea: 1.2% of TRULANCE-treated patients and 0% of placebo-treated patients withdrew due to diarrhea . Less Common Adverse Reactions Adverse reactions reported in 1% or more but less than 2% of TRULANCE-treated patients and at an incidence greater than placebo were: nausea, nasopharyngitis, upper respiratory tract infection, urinary tract infection, and dizziness. Two patients reported increased liver biochemical tests (alanine aminotransferase (ALT) greater than 5 to 15 times the upper limit of normal). 6.2 Postmarketing Experience The following adverse reactions have been identi