Oxybutynin Chloride (Page 3 of 4)

Geriatric Use

Clinical studies of oxybutynin chloride did not include sufficient numbers of subjects age 65 and over to determine whether they respond differently from younger patients. Other reported clinical experience has not identified differences in responses between healthy elderly and younger patients; however, a lower initial starting dose of 2.5 mg given 2 or 3 times a day has been recommended for the frail elderly due to a prolongation of the elimination half-life from 2 to 3 hours to 5 hours.2,3,4 In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.

ADVERSE REACTIONS

The safety and efficacy of oxybutynin chloride was evaluated in a total of 199 patients in three clinical trials. These participants were treated with oxybutynin chloride 5 mg/day to 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 Oxybutynin Chloride (5 to 20 mg/day)
Body System Adverse Event Oxybutynin Chloride
(5 to 20 mg/day) (n=199)
Infections and Infestations Urinary tract infection 6.5%
Psychiatric Disorders Insomnia 5.5%
Nervousness 6.5%
Nervous System Disorders Dizziness 16.6%
Somnolence 14.0%
Headache 7.5%
Eye Disorders Blurred vision 9.6%
Gastrointestinal Disorders Dry mouth 71.4%
Constipation 15.1%
Nausea 11.6%
Dyspepsia 6.0%
Renal and Urinary Disorders Urinary Hesitation 8.5%
Urinary Retention 6.0%

The most common adverse events reported by patients receiving oxybutynin chloride 5 to 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 oxybutynin chloride (5 to 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 oxybutynin chloride:

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

Nervous System Disorders: convulsions

Eye Disorders: cycloplegia, mydriasis, glaucoma

Cardiac Disorders: tachycardia, QT interval prolongation, chest discomfort

Gastrointestinal Disorders: decreased gastrointestinal motility, frequent bowel movement

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

Metabolism and Nutrition Disorders: anorexia

Respiratory, Thoracic and Mediastinal Disorders: dysphonia

OVERDOSAGE

Treatment should be symptomatic and supportive. Activated charcoal as well as a cathartic may be administered.

Overdosage with oxybutynin chloride has been associated with anticholinergic effects including central nervous system excitation (e.g., restlessness, tremor, irritability, convulsions, delirium, hallucinations), flushing, fever, dehydration, cardiac arrhythmia, vomiting, and urinary retention. Other symptoms may include hypotension or hypertension, respiratory failure, paralysis, and coma.

Ingestion of 100 mg oxybutynin chloride in association with alcohol has been reported in a 13-year-old boy who experienced memory loss, and a 34-year-old woman who developed stupor, followed by disorientation and agitation on awakening, dilated pupils, dry skin, cardiac arrhythmia, and retention of urine. Both patients fully recovered with symptomatic treatment.

DOSAGE AND ADMINISTRATION

Adults

The usual dose is one 5 mg tablet two to three times a day. The maximum recommended dose is one 5 mg tablet four times a day. A lower starting dose of 2.5 mg two or three times a day is recommended for the frail elderly.

Pediatric patients over 5 years of age

The usual dose is one 5 mg tablet two times a day. The maximum recommended dose is one 5 mg tablet three times a day.

HOW SUPPLIED

Oxybutynin chloride tablets, USP are supplied in the following form:

5 mg-round, white, 5/16″ diameter, single-scored tablets, debossed 832 and 38

Pharmacist: Dispense in a tight, light-resistant container as defined in the USP.

Store at 20° to 25°C (68° to 77°F); excursions permitted to 15° to 30°C (59° to 86°F) [See USP Controlled Room Temperature].

Keep out of reach of children.

REFERENCES

  • Yong C et al. Effect of Food on the Pharmacokinetics of Oxybutynin in normal subjects. Pharm Res. 1991; 8 (Suppl.): S–320.
  • Hughes KM et al. Measurement of oxybutynin and its N-desethyl metabolite in plasma, and its application to pharmacokinetic studies in young, elderly and frail elderly volunteers. Xenobiotica. 1992; 22 (7): 859–869.
  • Ouslander J et al. Pharmacokinetics and Clinical Effects of Oxybutynin in Geriatric Patients. J. Urol. 1988; 140: 47–50.
  • Yarker Y et al. Oxybutynin: A review of its Pharmacodynamic and Pharmacokinetic Properties, and its Therapeutic Use in Detrusor Instability. Drugs & Aging. 1995; 6 (3): 243–262.

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