Medications and Drugs
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.
Reference: FDA Prescribing Information
Last Editorial Review: 12/13/2005
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
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