Pharmacy Editor: Jay W. Marks, MD

GENERIC NAME: dicyclomine

BRAND NAME: Bentyl, Byclomine, Dibent, Di-Spaz, Dilomine

DRUG CLASS AND MECHANISM: Dicyclomine is a drug that is used for treating irritable bowel syndrome (IBS). Dicyclomine is in a class of drugs called anticholinergics. Anticholinergic drugs block the effects of acetylcholine, the chemical transmitter that nerves release in order to cause muscles to contract. They prevent contraction of the 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. Dicyclomine was approved by the FDA in 1950.

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes

PREPARATIONS: Capsules: 10, and 20 mg. Tablets: 20 mg. Syrup: 10 mg/5 mL. Injection (Intramuscular): 10 mg/5 mL

STORAGE: Capsules and tablets should be stored at room temperature, between 15° (59°F) and 30°C (86°F).

PRESCRIBED FOR: Dicyclomine is used in the treatment of irritable bowel syndrome.

DOSING: 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 20 mg, 4 times daily.

DRUG INTERACTIONS: Excessive anticholinergic effects may occur when dicyclomine is combined with other drugs with anticholinergic effects such as clemastine (Tavist), diphenhydramine (Benadryl), promethazine (Phenergan), thioridazine (Mellaril), triflupromazine (Stelazine), amitriptyline (Elavil), amoxapine (Asendin), clomipramine (Anafranil), protriptyline (Vivactil), clozapine (Clozaril), cyclobenzaprine (Flexeril), disopyramide (Norpace). The combined effects of these drugs can lead to a greater incidence of dry mouth, blurred vision, confusion, agitation, increased heart rate, palpitations, constipation, urinary retention (difficulty urinating). Narcotics, e.g., oxycodone (Percocet, Percodan), hydrocodone (Vicodin) can interact with dicyclomine and result in greater depression of the muscles of the bowel and bladder resulting in greater constipation and difficulty urinating than may be seen with dicyclomine alone.

Dicyclomine adds to the sedating effects of alcohol and other drugs that cause sleepiness such as the benzodiazepine class of anti-anxiety drugs (e.g., Valium, Ativan, Klonopin, Xanax), the narcotic class of pain medications and its derivatives (e.g., Percocet, Vicodin, Dilaudid, Codeine, Darvon), the tricyclic class of antidepressants (e.g., Elavil, Tofranil, Norpramin), and certain antihypertensive medications (e.g., Catapres, Inderal).

Dicyclomine can reverse the muscle activity-promoting effects of cisapride (Propulsid) or metoclopramide (Reglan). Conversely, these latter two drugs can reverse the effects of dicyclomine.

Antacids and absorbent anti-diarrheals (e.g., Kaopectate) can decrease the absorption of dicyclomine. Therefore, doses of antacids or absorbent anti-diarrheals should be separated by at least 2 hours from doses of dicyclomine.

PREGNANCY: 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.

NURSING MOTHERS: 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.

SIDE EFFECTS: Side effects include dry mouth, blurred vision, confusion, agitation, increased heart rate, heart palpitations, constipation, difficulty urinating, and occasionally seizures can occur. Other potential side effects include changes in taste perception, difficulty swallowing, headache, nervousness, drowsiness, weakness, dizziness, impotence, flushing, difficulty falling asleep, nausea, vomiting, rash, bloating and difficulty breathing.

From the Doctors at MedicineNet.com

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