Dicyclomine injection (cyclopam )

Dicyclomine is an antispasmodic and anticholinergic (antimuscarinic) agent.

Dicyclomine HCl Injection is a sterile, pyrogen-free, aqueous solution for intramuscular injection (NOT FOR INTRAVENOUS USE).

Each mL contains 10 mg dicyclomine hydrochloride USP in sterile water for injection, made isotonic with sodium chloride. pH range is 3.5 to 5.5.

Treats irritable bowel syndrome, or spastic colon and colitis.

Dicyclomine Injection - Clinical Pharmacology

Dicyclomine relieves smooth muscle spasm of the gastrointestinal tract. Animal studies indicate that this action is achieved via a dual mechanism: (1) a specific anticholinergic effect (antimuscarinic) at the acetylcholine-receptor sites with approximately 1/8 the milligram potency of atropine (in vitro, guinea pig ileum); and (2) a direct effect upon smooth muscle (musculotropic) as evidenced by dicyclomine’s antagonism of bradykinin- and histamine-induced spasms of the isolated guinea pig ileum. Atropine did not affect responses to these two agonists. In vivo studies in cats and dogs showed dicyclomine to be equally potent against acetylcholine (ACh)- or barium chloride (BaCl2)-induced intestinal spasm while atropine was at least 200 times more potent against effects of ACh than BaCl2. Tests for mydriatic effects in mice showed that dicyclomine was approximately 1/500 as potent as atropine; antisialagogue tests in rabbits showed dicyclomine to be 1/300 as potent as atropine.

In man, dicyclomine is rapidly absorbed after oral administration, reaching peak values within 60 to 90 minutes. The principal route of elimination is via the urine (79.5% of the dose). Excretion also occurs in the feces, but to a lesser extent (8.4%). Mean half-life of plasma elimination in one study was determined to be approximately 1.8 hours when plasma concentrations were measured for 9 hours after a single dose. In subsequent studies, plasma concentrations were followed for up to 24 hours after a single dose, showing a secondary phase of elimination with a somewhat longer half-life. Mean volume of distribution for a 20 mg oral dose is approximately 3.65 L/kg suggesting extensive distribution in tissues.

In controlIed clinical trials involving over 100 patients who received drug, 82% of patients treated for functional bowel/irritable bowel syndrome with dicyclomine hydrochloride at initial doses of 160 mg daily (40 mg q.i.d.) demonstrated a favorable clinical response compared with 55% treated with placebo. (P<.05). In these trials, most of the side effects were typically anticholinergic in nature (see table) and were reported by 61% of the patients.

Side Effect	Dicyclomine Hydrochloride (40 mg q.i.d.) %	Placebo %
Dry Mouth	33	5
Dizziness	29	2
Blurred Vision	27	2
Nausea	14	6
Light-Headedness	11	3
Drowsiness	9	1
Weakness	7	1
Nervousness	6	2

Nine percent (9%) of patients were discontinued from the drug because of one or more of these side effects (compared with 2% in the placebo group). In 41% of the patients with side effects, side effects disappeared or were tolerated at the 160 mg daily dose without reduction. A dose reduction from 160 mg daily to an average daily dose of 90 mg was required in 46% of the patients with side effects who then continued to experience a favorable clinical response; their side effects either disappeared or were tolerated.

Dicyclomine Injection Side Effects - for the Professional

Dicyclomine Injection

Controlled clinical trials have provided frequency information for reported adverse effects of dicyclomine hydrochloride listed in a decreasing order of frequency.

Not all of the following adverse reactions have been reported with dicyclomine hydrochloride. Adverse reactions are included here that have been reported for pharmacologically similar drugs with anticholinergic/antispasmodic action.

Gastrointestinal: dry mouth, nausea, vomiting, constipation, bloated feeling, abdominal pain, taste loss, anorexia

Central Nervous System: dizziness, light-headedness, tingling, headache, drowsiness, weakness, nervousness, numbness, mental confusion and/or excitement (especially in elderly persons), dyskinesia, lethargy, syncope, speech disturbance, insomnia

Ophthalmologic: blurred vision, diplopia, mydriasis, cycloplegia, increased ocular tension

Dermatologic/Allergic: rash, urticaria, itching, and other dermal manifestation; severe allergic reaction or drug idiosyncrasies including anaphylaxis

Genitourinary: urinary hesitancy, urinary retention

Cardiovascular: tachycardia, palpitations

Respiratory: dyspnea, apnea, asphyxia

Other: decreased sweating, nasal stuffiness or congestion, sneezing, throat congestion, impotence, suppression of lactation

With the injectable form, there may be temporary sensation of light-headedness. Some local irritation and focal coagulation necrosis may occur following the I.M. injection of the drug.