Side Effects of Linzess (linaclotide)

Linzess (linaclotide) is the first in a new class of drugs called guanylate cyclase-C used to relieve symptoms of irritable bowel syndrome (IBS) with constipation and for treating chronic constipation of unknown cause (idiopathic constipation). 

Linzess works locally in the intestine (it is not absorbed into the body) to increase bowel movements and reduce pain. Linzess' effects are due to an increase in the production of a chemical called cyclic guanosine monophosphate which increases fluid secretion into the intestine and reduces the sensitivity of pain-sensing nerves. 

Common side effects of Linzess include

• diarrhea,
• stomach pain,
• gas,
• stomach distention.

Serious side effects of Linzess include

• severe diarrhea,
• headache,
• fatigue,
• respiratory infections,
• sinusitis,
• stomach or intestinal viral infections, and rarely,
• passage of blood from the rectum.

Drug interaction studies have not been conducted with Linzess. Linzess has not been adequately evaluated in pregnant women. It is unknown if Linzess is excreted in breast milk. 

It is unlikely Linzess is excreted in breast milk because it is poorly absorbed and therefore undetectable in blood at recommended doses. Consult your doctor before breastfeeding.

The most common side effects of linaclotide are:

• diarrhea,
• stomach pain,
• gas, and
• stomach distention.

Linaclotide should be stopped if patients develop severe diarrhea. Other important side effects include:

• headache,
• fatigue,
• respiratory infections,
• sinusitis, and
• stomach or intestinal viral infections.

Rarely, patients may experience passage of blood from the rectum.

Clinical Trials Experience

Because clinical trials 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.

Exposure in clinical development included approximately 2570, 2040, and 1220 patients with either IBS-C or CIC treated with Linzess for 6 months or longer, 1 year or longer, and 18 months or longer, respectively (not mutually exclusive).

Demographic characteristics were comparable between treatment groups in all studies.

Irritable Bowel Syndrome With Constipation (IBS-C)

Most Common Adverse Reactions

The data described below reflect exposure to Linzess in the two placebo-controlled clinical trials involving 1605 adult patients with IBS-C (Trials 1 and 2). Patients were randomized to receive placebo or 290 mcg Linzess once daily on an empty stomach for up to 26 weeks.

Table 1 provides the incidence of adverse reactions reported in at least 2% of IBS-C patients in the Linzess treatment 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 (1 and 2) in Patients with IBS-C

Diarrhea

• Diarrhea was the most commonly reported adverse reaction of the Linzess-treated patients in the pooled IBS-C pivotal placebo-controlled trials.
• In these trials, 20% of Linzess-treated patients reported diarrhea compared to 3% of placebo-treated patients.
• Severe diarrhea was reported in 2% of the Linzess-treated patients versus less than 1% of the placebo-treated patients, and 5% of Linzess-treated patients discontinued due to diarrhea vs less than 1% of placebo-treated patients.
• The majority of reported cases of diarrhea started within the first 2 weeks of Linzess treatment.

Adverse Reactions Leading to Discontinuation

• In placebo-controlled trials in patients with IBS-C, 9% of patients treated with Linzess and 3% of patients treated with placebo discontinued prematurely due to adverse reactions.
• In the Linzess treatment group, the most common reasons for discontinuation due to adverse reactions were diarrhea (5%) and abdominal pain (1%).
• In comparison, less than 1% of patients in the placebo group withdrew due to diarrhea or abdominal pain.

Adverse Reactions Leading to Dose Reductions

• In the open-label, long-term trials, 2147 patients with IBS-C received 290 mcg of Linzess daily for up to 18 months.
• In these trials, 29% of patients had their dose reduced or suspended secondary to adverse reactions, the majority of which were diarrhea or other GI adverse reactions.

Less Common Adverse Reactions

• Defecation urgency, fecal incontinence, vomiting, and gastroesophagal reflux disease were reported in <2% of patients in the Linzess treatment group and at an incidence greater than in the placebo treatment group.

Chronic Idiopathic Constipation (CIC)

Most Common Adverse Reactions

The data described below reflect exposure to Linzess in the two double-blind placebo-controlled clinical trials of 1275 adult patients with CIC (Trials 3 and 4).

• Patients were randomized to receive placebo or 145 mcg Linzess or 290 mcg Linzess once daily on an empty stomach, for at least 12 weeks.
• Table 2 provides the incidence of adverse reactions reported in at least 2% of CIC patients in the 145 mcg Linzess treatment group and at an incidence that was greater than in the placebo treatment group.

Table 2: Most Common Adverse Reactions^a in the Two Placebo-controlled Trials (3 and 4) in Patients with CIC

The safety of a 72 mcg dose was evaluated in an additional placebo-controlled trial in which 1223 patients were randomized to Linzess 72 mcg, 145 mcg, or placebo once daily for 12 weeks (Trial 5).

In Trial 5, adverse reactions that occurred at a frequency of ≥ 2% in Linzess-treated patients (n=411 in each Linzess 72 mcg and 145 mcg group) and at a higher rate than placebo (n=401) were:

• Diarrhea (Linzess 72 mcg 19%; Linzess 145 mcg 22%; placebo 7%)
• Abdominal distension (Linzess 72 mcg 2%; Linzess 145 mcg 1%; placebo < 1%)

Diarrhea

This section summarizes information from Trials 3 and 4 (pooled) and Trial 5 regarding diarrhea, the most commonly reported adverse reaction reported in Linzess-treated patients in CIC placebo-controlled studies.

In all trials, the majority of reported cases of diarrhea started within the first 2 weeks of Linzess treatment.

Severe diarrhea was reported in less than 1% of the 72 mcg Linzess-treated patients (Trial 5), in 2% of the 145 mcg Linzess-treated patients (Trials 3 and 4; Trial 5), and less than 1% of the placebo-treated patients (Trials 3, 4, and 5).

Adverse Reactions Leading to Discontinuation

• In placebo-controlled trials in patients with CIC, 3% of patients treated with 72 mcg (Trial 5) and between 5% (Trial 5) and 8% (Trials 3 and 4) of patients treated with 145 mcg of Linzess discontinued prematurely due to adverse reactions compared to between less than 1% (Trial 5) and 4% (Trials 3 and 4) of patients treated with placebo.
• In patients treated with 72 mcg Linzess the most common reason for discontinuation due to adverse reactions was diarrhea (2% in Trial 5) and in patients treated with 145 mcg Linzess, the most common reasons for discontinuation due to adverse reactions were diarrhea (3% in Trial 5 and 5% in Trials 3 and 4) and abdominal pain (1% in Trials 3 and 4). In comparison, less than 1% of patients in the placebo group withdrew due to diarrhea or abdominal pain (Trials 3 and 4; Trial 5).

Adverse Reactions Leading to Dose Reductions

• In the open-label, long-term trials, 1129 patients with CIC received 290 mcg of Linzess daily for up to 18 months.
• In these trials, 27% of patients had their dose reduced or suspended secondary to adverse reactions, the majority of which were diarrhea or other GI adverse reactions.

Less Common Adverse Reactions

• Defecation urgency, fecal incontinence, dyspepsia, and viral gastroenteritis, were reported in less than 2% of patients in the Linzess treatment group and at an incidence greater than placebo treatment group.

Postmarketing Experience

• The following adverse reactions have been identified during post approval use of Linzess.
• Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
• Hematochezia, rectal hemorrhage, nausea, and allergic reactions, urticaria or hives.

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