Side Effects of Ditropan XL (oxybutynin)

Ditropan XL (oxybutynin) is an antispasmodic and anticholinergic drug used to treat urinary bladder spasm.

Ditropan XL has a dual mechanism of action. Contraction of the smooth muscle of the bladder is stimulated by the release of acetylcholine by the nerves within the bladder and the attachment of the acetylcholine to receptors on the surface of the bladder's muscle cells.

Ditropan XL suppresses involuntary contractions of the bladder's smooth muscle (spasms) by blocking the release of acetylcholine. This is referred to as an "anticholinergic effect." Ditropan XL also directly relaxes the bladder's outer layer of muscle (the detrusor muscle). 

Common side effects of Ditropan XL include

• dry mouth,
• constipation,
• tiredness,
• headache,
• diarrhea,
• urinary tract infection (UTIs),
• blurred vision, difficulty urinating, and local reactions at the application site such as itching and rash with transdermal patch use.

Serious side effects of Ditropan XL include serious hypersensitivity reactions involving swelling of the throat, lips, and tongue.

Drug interactions of Ditropan XL include other drugs with anticholinergic effects, such as diphenhydramine, dimenhydrinate, scopolamine, benztropine, disopyramide, thioridazine, and amitriptyline, because it will likely result in an increased frequency and/or severity of anticholinergic side effects which include

• dry mouth,
• constipation,
• confusion,
• blurred vision,
• urinary retention, and
• an increased heart rate or palpitations.

Combining pramlintide with Ditropan XL may severely reduce bowel movements. Ditropan XL may delay passage of potassium tablets through the digestive system and result in ulceration or narrowing of the small intestine.

No controlled studies of Ditropan XL have been done in pregnant women. The potential benefit of Ditropan XL needs to be weighed against any theoretical harm. It is unknown if Ditropan XL is excreted in human milk. Consult your doctor before breastfeeding.

The most common side effects of oxybutynin are

• dry mouth,
• constipation,
• tiredness, and
• headache.

About 1 in every 14 patients taking oxybutynin tablets cannot tolerate it because of side effects. Diarrhea, urinary tract infections, blurred vision, and difficulty urinating also may occur.

The transdermal patch or gel may also cause local reactions at the application sites such as itching and rash. Transdermal patches or gel cause fewer side effects than the tablets. Serious hypersensitivity reactions involving swelling of the throat, lips, and tongue also may occur.

The safety and efficacy of Ditropan (oxybutynin chloride) was evaluated in a total of 199 patients in three clinical trials. These participants were treated with Ditropan 5-20 mg/day for up to 6 weeks. Table 3 shows the incidence of adverse events judged by investigators to be at least possibly related to treatment and reported by at least 5% of patients.

Table 3 : Incidence (%) of Adverse Events Reported by ≥ 5% of Patients Using Ditropan (5-20mg/day)

The most common adverse events reported by patients receiving Ditropan 5-20 mg/day were the expected side effects of anticholinergic agents. The incidence of dry mouth was dose-related.

In addition, the following adverse events were reported by 1 to < 5% of patients using Ditropan (5-20 mg/day) in all studies.

Infections and Infestations: nasopharyngitis, upper respiratory tract infection, bronchitis, cystitis, fungal infection;

Metabolism and Nutrition Disorders: fluid retention;

Psychiatric Disorders: confusional state;

Nervous System Disorders: dysgeusia, sinus headache;

Eye Disorders: keratoconjunctivitis sicca, eye irritation;

Cardiac Disorders: palpitations, sinus arrhythmia;

Vascular Disorders: flushing;

Respiratory, Thoracic and Mediastinal Disorders: nasal dryness, cough, pharyngolaryngeal pain, dry throat, sinus congestion, hoarseness, asthma, nasal congestion;

Gastrointestinal Disorders: diarrhea, abdominal pain, loose stools, flatulence, vomiting, abdominal pain upper, dysphagia, aptyalism, eructation, tongue coated;

Skin and Subcutaneous Tissue Disorders: dry skin, pruritis;

Musculoskeletal and Connective Tissue Disorders: back pain, arthralgia, pain in extremity, flank pain;

Renal and Urinary Disorders: dysuria, pollakiuria;

General Disorders and Administration Site Conditions: fatigue, edema peripheral, asthenia, pain, thirst, edema;

Investigations: blood pressure increased, blood glucose increased, blood pressure decreased;

Injury, Poisoning, and Procedural Complications: fall.

Postmarketing Surveillance

Because postmarketing adverse events 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. The following additional adverse events have been reported from worldwide postmarketing experience with Ditropan:

Psychiatric Disorders: psychotic disorder, agitation, hallucination, memory impairment;

Nervous System Disorders: convulsions;

Eye Disorders: cycloplegia, mydriasis, glaucoma;

Cardiac Disorders: tachycardia, QT interval prolongation;

Gastrointestinal Disorders: decreased gastrointestinal motility;

Skin and Subcutaneous Tissue Disorders: rash, decreased sweating;

Renal and Urinary Disorders: impotence;

Reproductive System and Breast Disorders: Suppression of lactation;

General Disorders and Administration Site Conditions: hypersensitivity reactions, including angioedema with airway obstruction, urticaria, and face edema; rare anaphylactic reactions requiring hospitalization for emergency treatment.

The concomitant use of oxybutynin with other anticholinergic drugs or with other agents which produce dry mouth, constipation, somnolence (drowsiness), and/or other anticholinergic-like effects may increase the frequency and/or severity of such effects.

Anticholinergic agents may potentially alter the absorption of some concomitantly administered drugs due to anticholinergic effects on gastrointestinal motility. This may be of concern for drugs with a narrow therapeutic index.

Mean oxybutynin chloride plasma concentrations were approximately 3-4 fold higher when Ditropan was administered with ketoconazole, a potent CYP3A4 inhibitor.

Other inhibitors of the cytochrome P450 3A4 enzyme system, such as antimycotic agents (e.g., itraconazole and miconazole) or macrolide antibiotics (e.g., erythromycin and clarithromycin), may alter oxybutynin mean pharmacokinetic parameters (i.e., Cmax and AUC). The clinical relevance of such potential interactions is not known. Caution should be used when such drugs are co-administered.