dicyclomine hydrochloride
Antispas, A-Spas, Bentyl, Bentylol ◆, Byclomine, Dibent, Dilomine, Di-Spaz, Formulex ◆, Lomine ◆, Neoquess, Or-Tyl, Spasmoban ◆, Spasmoject

Available forms
Available by prescription only
Capsules: 10 mg, 20 mg
Injection: 10 mg/ml in 2-ml vials, 10-ml vials, 2-ml ampules
Syrup: 10 mg/5 ml
Tablets: 20 mg

Indications and dosages
 Irritable bowel syndrome and other functional GI disorders. Adults: Initially, 20 mg P.O. q.i.d.; then increase to 40 mg P.O. q.i.d. during first week of therapy unless precluded by adverse reactions. Or, 20 mg I.M. q 4 to 6 hours.
Children age 2 and older: 10 mg P.O. t.i.d. or q.i.d.
Infants ages 6 months to 23 months: 5 to 10 mg P.O. t.i.d. or q.i.d.
 Infant colic ◇. Infants age 6 months and older: 5 to 10 mg P.O. t.i.d. or q.i.d. Adjust dosage according to patient’s needs and response.

Pharmacodynamics
Antispasmodic action: Dicyclomine exerts a nonspecific, direct spasmolytic action on smooth muscle. It also has some local anesthetic properties that may contribute to spasmolysis in the GI and biliary tracts.
Antimuscarinic action: Drug blocks parasympathetic nerve impulses at the acetylcholine-receptor site, relieving smooth-muscle contraction, thereby slowing bowel action and decreasing production of stomach acid.

Pharmacokinetics
Absorption: About 67% of an oral dose is absorbed from the GI tract.
Distribution: Largely unknown.
Metabolism: Unknown.
Excretion: After oral administration, 80% of a dose is excreted in urine and 10% in feces.

Contraindications and precautions
Contraindicated in patients with obstructive uropathy, obstructive disease of the GI tract, reflux esophagitis, severe ulcerative colitis, myasthenia gravis, hypersensitivity to anticholinergics, unstable CV status in acute hemorrhage, or glaucoma. Also contraindicated in breast-feeding women and in children younger than age 6 months.
  Use cautiously in patients with autonomic neuropathy, hyperthyroidism, coronary artery disease, arrhythmias, heart failure, hypertension, hiatal hernia, hepatic or renal disease, prostatic hyperplasia, and ulcerative colitis.

Interactions
Drug-drug. Amantadine, antihistamines, antiparkinsonians, disopyramide, glutethimide, meperidine, phenothiazines, procainamide, quinidine, tricyclic antidepressants: May cause additive adverse effects. Avoid use together.
Antacids: Decreases oral absorption of anticholinergics. Give dicyclomine at least 1 hour before antacids.
Digoxin (slow-dissolving tablets): Increases digoxin levels. Monitor digoxin levels closely.
Ketoconazole, levodopa: Decreases GI absorption. Avoid use together.
Methotrimeprazine: May enhance risk of extrapyramidal reactions. Avoid use together.
Oral potassium supplements (especially wax-matrix forms): May increase potassium-induced GI ulcerations. Use together cautiously.

Adverse reactions
CNS: headache; dizziness; insomnia; fever; light-headedness; drowsiness; nervousness, confusion, and excitement in elderly patients.
CV: palpitations, tachycardia.
EENT: blurred vision, increased intraocular pressure, mydriasis.
GI: nausea, vomiting, constipation, dry mouth, abdominal distention, heartburn, paralytic ileus.
GU: urinary hesitancy, urine retention, impotence.
Skin: urticaria, decreased sweating or possible anhidrosis, other dermal manifestations, local irritation.
Other: allergic reactions, dependence.

Effects on lab test results
None reported.

Overdose and treatment
Signs and symptoms of overdose include curare-like CNS stimulation followed by depression, and such psychotic symptoms as disorientation, confusion, hallucinations, delusions, anxiety, agitation, and restlessness. Peripheral effects may include dilated, nonreactive pupils; hot, flushed, dry skin; tachycardia; hypertension; and increased respiration.
 Treatment is primarily symptomatic and supportive, as needed. Maintain patent airway. If patient is alert, induce emesis (or use gastric lavage) and follow with a saline cathartic and activated charcoal to prevent further drug absorption. In severe cases, physostigmine may be administered to block the antimuscarinic effects of dicyclomine. Give fluids, as needed, to treat shock; diazepam to control psychotic symptoms; and pilocarpine (instilled into the eyes) to relieve mydriasis. If urine retention occurs, catheterization may be needed.

Special considerations
 ALERT High environmental temperatures may induce heatstroke during drug use. If symptoms occur, discontinue drug.
• Never give dicyclomine I.V. or S.C.
Breast-feeding patients
• Dicyclomine may appear in breast milk; it also may decrease milk production. Avoid use in breast-feeding women.
Pediatric patients
• Safety and effectiveness in children haven’t been established. Administer cautiously to infants age 6 months and older; seizures have been reported. Contraindicated in infants younger than age 6 months.
Geriatric patients
• Administer drug cautiously and in reduced doses.

Patient education
• Tell patient that syrup form may be diluted with water.
• Warn patient that high environmental temperatures may induce heatstroke during therapy; tell patient to avoid such temperatures.
• Advise patient to avoid driving and other hazardous activities if drowsiness or blurred vision occurs.
• Tell patient to report rash or other skin eruption.

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use