Bentyl (dicyclomine) vs. Linzess (linaclotide)

• Dicyclomine and Linzess (linaclotide) are used to treat irritable bowel syndrome (IBS).
• Linzess is specifically used to treat symptoms of irritable bowel syndrome (IBS) with constipation. It is also used to treat chronic constipation of unknown cause (idiopathic constipation).
• Dicyclomine and Linzess belong to different drug classes. Dicyclomine is an anticholinergic and Linzess is a guanylate cyclase-C agonist.
• A brand name for dicyclomine is Bentyl.
• Side effects of dicyclomine and Linzess that are similar include headache.
• Side effects of dicyclomine that are different from Linzess include dry mouth, blurred vision, confusion, agitation, increased heart rate, heart palpitations, constipation, difficulty urinating, seizures, changes in taste, difficulty swallowing, nervousness, drowsiness, weakness, dizziness, impotence, flushing, delirium, difficulty falling asleep (insomnia), nausea, vomiting, rash, skin redness, fainting, bloating, and difficulty breathing.
• Side effects of Linzess that are different from dicyclomine include diarrhea, stomach pain, gas, stomach distention, fatigue, respiratory infections, sinusitis, stomach or intestinal viral infections, and passage of blood from the rectum (rare).

Dicyclomine is an anticholinergic used to treat irritable bowel syndrome (IBS). Anticholinergic drugs block the effects of acetylcholine, the chemical transmitter that nerves release in order to cause muscles to contract. They prevent contraction of muscles by blocking the acetylcholine receptors on the muscle cells. Anticholinergic drugs also have a direct relaxing effect on muscle. Dicyclomine is used to reduce contraction of the muscles in the intestines.

Linzess (linaclotide) is a guanylate cyclase-C agonist used to treat symptoms of irritable bowel syndrome (IBS) with constipation and 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.

Dicyclomine

Common side effects include:

• dry mouth (xerostomia),
• blurred vision,
• confusion,
• agitation,
• increased heart rate,
• heart palpitations,
• constipation,
• difficulty urinating, and
• seizures.

Other important side effects include:

• changes in taste perception,
• difficulty swallowing,
• headache,
• nervousness,
• drowsiness,
• weakness,
• dizziness,
• impotence,
• flushing,
• delirium,
• difficulty falling asleep,
• nausea,
• vomiting,
• rash,
• erythema,
• fainting,
• bloating, and
• difficulty breathing.

Linzess

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.

Dicyclomine

The recommended starting oral dose of dicyclomine is 20 mg given 4 times daily. The dose can be increased to 40 mg 4 times daily. The recommended intramuscular injection is 10 to 20 mg 4 times daily. The intramuscular injection is only used for 1 to 2 days if a patient cannot take capsules or tablets.

Linzess

The dose for treating IBS with constipation is 290 mcg once daily, and the dose for treating chronic idiopathic constipation is 145 mcg once daily. Linaclotide should be taken on an empty stomach at least 30 minutes before the first meal of the day.

Dicyclomine

Antiglaucoma Agents

Anticholinergics antagonize the effects of antiglaucoma agents and may increase intraoccular pressure. Anticholinergic drugs in the presence of increased intraocular pressure may be hazardous when taken concurrently with agents such as corticosteroids. Use of Bentyl in patients with glaucoma is not recommended.

Other Drugs with Anticholinergic Activity

The following agents may increase certain actions or side effects of anticholinergic drugs including Bentyl:

• amantadine,
• antiarrhythmic agents of Class I (for example, quinidine),
• antihistamines,
• antipsychotic agents (for example, phenothiazines),
• benzodiazepines,
• MAO inhibitors,
• narcotic analgesics (for example, meperidine),
• nitrates and nitrites,
• sympathomimetic agents,
• tricyclic antidepressants, and
• other drugs having anticholinergic activity.

Other Gastrointestinal Motility Drugs

Interaction with other gastrointestinal motility drugs may antagonize the effects of drugs that alter gastrointestinal motility, such as metoclopramide.

Effect of Antacids

Because antacids may interfere with the absorption of anticholinergic agents including Bentyl, simultaneous use of these drugs should be avoided.

Effect on Absorption of Other Drugs

Anticholinergic agents may affect gastrointestinal absorption of various drugs by affecting on gastrointestinal motility, such as slowly dissolving dosage forms of digoxin; increased serum digoxin concentration may result.

Effect on Gastric Acid Secretion

The inhibiting effects of anticholinergic drugs on gastric hydrochloric acid secretion are antagonized by agents used to treat achlorhydria and those used to test gastric secretion.

Linzess

Drug interaction studies have not been conducted.

Dicyclomine

There are no adequate studies of the effect of dicyclomine in pregnant women at recommended doses (80-160 mg/day). Observation of women who received dicyclomine (up to 40 mg/day) containing products during the first trimester of pregnancy did not reveal any increased risk of harm to the fetus.

Dicyclomine is excreted into breast milk. Since there have been reports of apnea (cessation of breathing) when dicyclomine has been given to children, it should not be used by nursing mothers.

Linzess

Linaclotide has not been adequately evaluated in pregnant women.

It is not known whether linaclotide is excreted in human milk. It is unlikely that linaclotide is excreted in breast milk because it is poorly absorbed and therefore undetectable in blood at recommended doses.