Bentyl

SIDE EFFECTS

The pattern of adverse effects seen with dicylomine is mostly related to its pharmacological actions at muscarinic receptors [see CLINICAL PHARMACOLOGY]. They are a consequence of the inhibitory effect on muscarinic receptors within the autonomic nervous system. These effects are dose-related and are usually reversible when treatment is discontinued.

The most serious adverse reactions reported with dicyclomine hydrochloride include cardiovascular and central nervous system symptoms [see WARNINGS AND PRECAUTIONS].

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

The data described below reflect exposure in controlled clinical trials involving over 100 patients treated for functional bowel/irritable bowel syndrome with dicyclomine hydrochloride at initial doses of 160 mg daily (40 mg four times a day)

In these trials most of the side effects were typically anticholinergic in nature and were reported by 61% of the patients. Table 1 presents adverse reactions (MedDRA 13.0 preferred terms) by decreasing order of frequency in a side-by-side comparison with placebo.

Table 1: Adverse reactions experienced in controlled clinical trials with decreasing order of frequency

MedDRA Preferred Term Dicyclomine Hydrochloride (40 mg four times a day)
%
Placebo
%
Dry Mouth 33 5
Dizziness 40 5
Vision blurred 27 2
Nausea 14 6
Somnolence 9 1
Asthenia 7 1
Nervousness 6 2

Nine percent (9%) of patients were discontinued from BENTYL 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.

Postmarketing Experience

The following adverse reactions, presented by system organ class in alphabetical order, have been identified during post approval use of BENTYL. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Cardiac disorders: palpitations, tachyarrhythmias

Eye disorders: cycloplegia, mydriasis, vision blurred

Gastrointestinal disorders: abdominal distension, abdominal pain, constipation, dry mouth, dyspepsia, nausea, vomiting

General disorders and administration site conditions: fatigue, malaise

Immune System Disorders: drug hypersensitivity including face edema, angioedema, anaphylactic shock

Nervous system disorders: dizziness, headache, somnolence, syncope

Psychiatric disorders: As with the other anti-cholinergic drugs, cases of delirium or symptoms of delirium such as amnesia (or transient global amnesia), agitation, confusional state, delusion, disorientation, hallucination (including visual hallucination) as well as mania, mood altered and pseudodementia, have been reported with the use of Dicyclomine. Nervousness and insomnia have also been reported.

Reproductive system and breast disorders: suppressed lactation

Respiratory, thoracic and mediastinal disorders: dyspnoea, nasal congestion

Skin and subcutaneous tissue disorder: dermatitis allergic, erythema, rash

Cases of thrombosis, thrombophlebitis and injection site reactions such as local pain, edema, skin color change and even reflex sympathetic dystrophy syndrome have been reported following Inadvertent IV injection of BENTYL.

Adverse Reactions Reported with Similar Drugs with Anticholinergic/Antispasmodic Action

Gastrointestinal: anorexia

Central Nervous System: tingling, numbness, dyskinesia, speech disturbance, insomnia

Peripheral Nervous System: With overdosage, a curare-like action may occur (i.e., neuromuscular blockade leading to muscular weakness and possible paralysis)

Ophthalmologic: diplopia, increased ocular tension

Dermatologic/Allergic: urticaria, itching, and other dermal manifestations

Genitourinary: urinary hesitancy, urinary retention in patients with prostatic hypertrophy

Cardiovascular: hypertension

Respiratory: apnea

Other: decreased sweating, sneezing, throat congestion, impotence. With the injectable form, there may be temporary sensation of light-headedness. Some local irritation and focal coagulation necrosis may occur following the intramuscular injection of BENTYL.

Read the Bentyl (dicyclomine) Side Effects Center for a complete guide to possible side effects

DRUG INTERACTIONS

Antiglaucoma Agents

Anticholinergics antagonize the effects of antiglaucoma agents. 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 [see CONTRAINDICATIONS].

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 (e.g., quinidine), antihistamines, antipsychotic agents (e.g., phenothiazines), benzodiazepines, MAO inhibitors, narcotic analgesics (e.g., 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.

Read the Bentyl Drug Interactions Center for a complete guide to possible interactions

Last reviewed on RxList: 2/1/2013
This monograph has been modified to include the generic and brand name in many instances.

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