FDA Label for Oxytrol

1 Indications And Usage

OXYTROL is a muscarinic antagonist indicated for the treatment of overactive bladder in men with symptoms of urge urinary incontinence, urgency, and frequency.

2 Dosage And Administration

OXYTROL 3.9 mg/day should be applied to dry, intact skin on the abdomen, hip, or buttock twice weekly (every 3 or 4 days). A new application site should be selected with each new system to avoid re-application to the same site within 7 days.

3 Dosage Forms And Strengths

Transdermal System: 3.9 mg/day

4 Contraindications

The use of OXYTROL is contraindicated in the following conditions:

• Urinary retention
  
• Gastric retention
  
• Uncontrolled narrow-angle glaucoma
  
• Known serious hypersensitivity reaction to OXYTROL, oxybutynin, or to any of the components of OXYTROL [see Warnings and Precautions (5.5)].

5.1 Urinary Retention

Administer OXYTROL with caution in patients with clinically significant bladder outflow obstruction because of the risk of urinary retention [see Contraindications (4)].

5.2 Risks In Patients With Gastrointestinal Disorders

Administer OXYTROL with caution to patients with gastrointestinal obstructive disorders because of the risk of gastric retention [see Contraindications (4)].

OXYTROL, like other anticholinergic drugs, may decrease gastrointestinal motility and should be used with caution in patients with conditions such as ulcerative colitis or intestinal atony.

OXYTROL should be used with caution in patients who have hiatus hernia/gastroesophageal reflux and/or who are concurrently taking drugs (such as bisphosphonates) that can cause or exacerbate esophagitis.

5.3 Central Nervous System Effects

Products containing oxybutynin are associated with anticholinergic central nervous system (CNS) effects. A variety of CNS anticholinergic effects have been reported, including headache, dizziness, somnolence, confusion and hallucinations [see Adverse Events (6.2, 6.3)]. Patients should be monitored for signs of anticholinergic CNS effects, particularly after beginning treatment. Advise patients not to drive or operate heavy machinery until they know how OXYTROL affects them. If a patient experiences anticholinergic CNS effects, drug discontinuation should be considered.

5.4 Angioedema

Angioedema requiring hospitalization and emergency medical treatment has occurred with the first or subsequent doses of oral oxybutynin. In the event of angioedema, OXYTROL should be discontinued and appropriate therapy promptly provided.

5.5 Skin Hypersensitivity

Patients who develop skin hypersensitivity to OXYTROL should discontinue drug treatment.

5.6 Exacerbation Of Symptoms Of Myasthenia Gravis

Avoid use of OXYTROL in patients with myasthenia gravis, a disease characterized by decreased cholinergic activity at the neuromuscular junction. If experiencing exacerbation of symptoms of myasthenia gravis, oxybutynin-containing product should be discontinued and appropriate therapy promptly provided.

6.1 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 clinical practice.

The safety of OXYTROL was evaluated in a total of 417 patients who participated in two clinical efficacy and safety studies and an open-label extension. Additional safety information was collected in earlier phase trials. In the two pivotal studies, a total of 246 patients received OXYTROL during the 12-week treatment periods. A total of 411 patients entered the open-label extension and of those, 65 patients and 52 patients received OXYTROL for at least 24 weeks and at least 36 weeks, respectively.

No deaths were reported during treatment. No serious adverse events related to treatment were reported.

Adverse reactions reported in the pivotal trials are summarized in Tables 1 and 2 below.

Most adverse reactions were described as mild or moderate in intensity. Severe application site reactions were reported by 6.4% of OXYTROL-treated patients in Study 1 and by 5.0% of OXYTROL-treated patients in Study 2.

Adverse reactions that resulted in discontinuation were reported by 11.2% of OXYTROL-treated patients in Study 1 and 10.7% of OXYTROL-treated patients in Study 2. Most of these discontinuations were due to application site reaction. In the two pivotal studies, no patient discontinued OXYTROL treatment due to dry mouth.

In the open-label extension, the most common treatment-related adverse reactions were: application site pruritus, application site erythema, and dry mouth.

In a controlled clinical trial of skin sensitization, none of the 103 test subjects demonstrated skin hypersensitivity to OXYTROL.

6.2 Postmarketing Experience

The following adverse reactions have been identified during post approval use of OXYTROL. 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.

Nervous System Disorders: Memory impairment, dizziness, somnolence, confusion

Psychiatric Disorders: Delirium, hallucinations

7 Drug Interactions

No specific drug-drug interaction studies have been performed with OXYTROL.

7.1 Other Anticholinergics

The concomitant use of OXYTROL with other anticholinergic drugs, or with other agents that produce dry mouth, constipation, somnolence, 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.

7.2 Cytochrome P450 Inhibitors

Pharmacokinetic studies have not been performed with patients concomitantly receiving cytochrome P450 enzyme inhibitors, such as antimycotic agents (e.g., ketoconazole, itraconazole, and miconazole) or macrolide antibiotics (e.g., erythromycin and clarithromycin).

8.1       Pregnancy

Risk Summary

There are no studies with topical or oral oxybutynin use in pregnant women to inform a drug associated risk for birth defects or miscarriage. No adverse developmental outcomes were observed in animal reproduction studies when oxybutynin chloride was administered to pregnant rats and rabbits during organogenesis at approximately 50 and 1 times, respectively, the maximum human dose based on body surface area (see Data)

In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20% respectively.

Data            

Animal Data

Subcutaneous administration of oxybutynin chloride to rats at doses up to 25 mg/kg (approximately 50 times the human exposure based on surface area) and to rabbits at doses up to 0.4 mg/kg (approximately 1 times the human exposure based on body surface area) throughout the period of organogenesis revealed no evidence of harm to the fetus.

8.2       Lactation

Risk Summary

There is no information on the presence of oxybutynin in human milk, the effects on the breastfed child, or the effects on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for OXYTROL and any potential adverse effects on the breastfed child from OXYTROL or from the underlying maternal condition.

8.4 Pediatric Use

The safety and efficacy of OXYTROL in pediatric patients have not been established.

8.5 Geriatric Use

Forty-nine percent of OXYTROL-treated patients in the clinical studies were at least 65 years of age. No overall differences in safety or effectiveness were observed between these patients and younger patients, and other reported clinical experience has not identified differences in response between elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out [see Clinical Pharmacology (12.3)].

10 Overdosage

The plasma concentration of oxybutynin declines within 1 to 2 hours after removal of transdermal system(s). Patients should be monitored until symptoms resolve. Overdosage with oxybutynin has been associated with anticholinergic effects including CNS excitation, flushing, fever, dehydration, cardiac arrhythmia, vomiting, and urinary retention. Ingestion of 100 mg oral oxybutynin chloride in association with alcohol has been reported in a 13 year old boy who experienced memory loss, and in 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 recovered fully with treatment directed at their symptoms.

11 Description

OXYTROL (oxybutynin transdermal system) is designed to deliver oxybutynin over a 3- to 4-day interval after application to intact skin. OXYTROL is available as a 39 cm² system containing 36 mg of oxybutynin. OXYTROL has a nominal in vivo delivery rate of 3.9 mg oxybutynin per day through skin of average permeability (inter-individual variation in skin permeability is approximately 20%).

Oxybutynin is an antispasmodic, anticholinergic agent. Oxybutynin is administered as a racemate of R- and S-isomers. Chemically, oxybutynin is d, l (racemic) 4-diethylamino-2-butynyl phenylcyclohexylglycolate. The empirical formula of oxybutynin is C₂₂H₃₁NO₃. Its structural formula is:

The structural formula for Oxybutynin is an antispasmodic, anticholinergic agent. Oxybutynin is administered as a racemate of R- and S-isomers. Chemically, oxybutynin is d, l (racemic) 4-diethylamino-2-butynyl phenylcyclohexylglycolate. The empirical formula of oxybutynin is C22H31NO3. - oxytrol 01

Oxybutynin is a white powder with a molecular weight of 357. It is soluble in alcohol, but relatively insoluble in water.

OXYTROL is a matrix-type transdermal system composed of three layers as illustrated in Figure 1. Layer 1 (Backing Film) is a thin flexible polyester/ethylene-vinyl acetate film that provides the matrix system with occlusivity and physical integrity and protects the adhesive/drug layer. Layer 2 (Adhesive/Drug Layer) is a cast film of acrylic adhesive containing oxybutynin and triacetin, USP. Layer 3 (Release Liner) is two overlapped siliconized polyester strips that are peeled off and discarded by the patient prior to applying the matrix system.

12.1 Mechanism Of Action

The free base form of oxybutynin is pharmacologically equivalent to oxybutynin hydrochloride. Oxybutynin acts as a competitive antagonist of acetylcholine at postganglionic muscarinic receptors, resulting in relaxation of bladder smooth muscle. In patients with conditions characterized by involuntary detrusor contractions, cystometric studies have demonstrated that oxybutynin increases maximum urinary bladder capacity and increases the volume to first detrusor contraction.

Oxybutynin is a racemic (50:50) mixture of R- and S-isomers. Antimuscarinic activity resides predominantly in the R-isomer. The active metabolite, N-desethyloxybutynin, has pharmacological activity on the human detrusor muscle that is similar to that of oxybutynin in in vitro studies.

12.3 Pharmacokinetics

Absorption

Oxybutynin is transported across intact skin and into the systemic circulation by passive diffusion across the stratum corneum. The average daily dose of oxybutynin absorbed from the 39 cm² OXYTROL system is 3.9 mg. The average (SD) nominal dose, 0.10 (0.02) mg oxybutynin per cm² surface area, was obtained from analysis of residual oxybutynin content of systems worn over a continuous 4-day period during 303 separate occasions in 76 healthy volunteers. Following application of the first OXYTROL 3.9 mg/day system, oxybutynin plasma concentrations increase for approximately 24 to 48 hours, reaching average maximum concentrations of 3 to 4 ng/mL. Thereafter, steady concentrations are maintained for up to 96 hours. Absorption of oxybutynin is bioequivalent when OXYTROL is applied to the abdomen, buttocks, or hip. Average plasma concentrations measured during a randomized, crossover study of the three recommended application sites in 24 healthy men and women are shown in Figure 2.

Figure 2: Average plasma oxybutynin concentrations (Cp) in 24 healthy male and female volunteers during single-dose application of OXYTROL 3.9 mg/day to the abdomen, buttock, and hip (System removal at 96 hours). - oxytrol 03

Steady-state conditions are reached during the second OXYTROL application. Average steady-state plasma concentrations were 3.1 ng/mL for oxybutynin and 3.8 ng/mL for N-desethyloxybutynin (Figure 3). Table 3 provides a summary of pharmacokinetic parameters of oxybutynin in healthy volunteers after single and multiple applications of OXYTROL.

^‡  T_max given as median
^§  AUC_inf
^¶  AUC_0-96
^#Þ  AUC_0-84

Distribution

Oxybutynin is widely distributed in body tissues following systemic absorption. The volume of distribution was estimated to be 193 L after intravenous administration of 5 mg oxybutynin chloride.

Metabolism

Oxybutynin is metabolized primarily by the cytochrome P450 enzyme systems, particularly CYP3A4, found mostly in the liver and gut wall. Metabolites include phenylcyclohexylglycolic acid, which is pharmacologically inactive, and N-desethyloxybutynin, which is pharmacologically active.

After oral administration of oxybutynin, pre-systemic first-pass metabolism results in an oral bioavailability of approximately 6% and higher plasma concentration of the N-desethyl metabolite compared to oxybutynin (see Figure 4). The plasma concentration area under the time-concentration curve (AUC) ratio of N-desethyl metabolite to parent compound following a single 5 mg oral dose of oxybutynin chloride was 11.9:1.

Transdermal administration of oxybutynin bypasses first-pass gastrointestinal and hepatic metabolism, reducing the formation of the N-desethyl metabolite (see Figure 4). Only small amounts of CYP3A4 are found in skin, limiting pre-systemic metabolism during transdermal absorption. The resulting plasma concentration AUC ratio of N-desethyl metabolite to parent compound following multiple OXYTROL applications was 1.3:1.

Following intravenous administration, the elimination half-life of oxybutynin is approximately 2 hours. Following removal of OXYTROL, plasma concentrations of oxybutynin and N-desethyloxybutynin decline with an apparent half-life of approximately 7 to 8 hours.

Excretion

Oxybutynin is extensively metabolized by the liver, with less than 0.1% of the administered dose excreted unchanged in the urine. Also, less than 0.1% of the administered dose is excreted as the metabolite N-desethyloxybutynin.

Specific Populations:

Geriatric: The pharmacokinetics of oxybutynin and N-desethyloxybutynin were similar in older and younger patients.

Pediatric: The pharmacokinetics of oxybutynin and N-desethyloxybutynin were not evaluated in individuals younger than 18 years of age.

Gender: There were no significant differences in the pharmacokinetics of oxybutynin in healthy male and female volunteers following application of OXYTROL.

Race: Available data suggest that there are no significant differences in the pharmacokinetics of oxybutynin based on race in healthy volunteers following administration of OXYTROL. Japanese volunteers demonstrated a somewhat lower metabolism of oxybutynin to N-desethyloxybutynin compared to Caucasian volunteers.

13.1 Carcinogenesis, Mutagenesis, Impairment Of Fertility

A 24-month study in rats at dosages of oxybutynin chloride of 20, 80 and 160 mg/kg showed no evidence of carcinogenicity. These doses are approximately 6, 25 and 50 times the maximum exposure in humans taking an oral dose based on body surface area.

Oxybutynin chloride showed no increase of mutagenic activity when tested in Schizosaccharomyces pompholiciformis, Saccharomyces cerevisiae, and Salmonella typhimurium test systems. Reproduction studies with oxybutynin chloride in the mouse, rat, hamster, and rabbit showed no definite evidence of impaired fertility.

14 Clinical Studies

The efficacy and safety of OXYTROL were evaluated in patients with urge urinary incontinence in two controlled studies and one open-label extension. Study 1 was a placebo controlled study, comparing the safety and efficacy of OXYTROL at dose levels of 1.3, 2.6, and 3.9 mg/day to placebo in 520 patients. Open-label treatment was available for patients completing the study. Study 2 was a study comparing the safety and efficacy of OXYTROL 3.9 mg/day versus active and placebo controls in 361 patients.

Study 1 was a randomized, double-blind, placebo-controlled, parallel group study of three dose levels of OXYTROL conducted in 520 patients. The 12-week double-blind treatment included an OXYTROL dose of 3.9 mg/day or matching placebo. An open-label, dose titration treatment extension allowed continued treatment for up to an additional 40 weeks for patients completing the double-blind period. The majority of patients were Caucasian (91%) and female (92%) with a mean age of 61 years (range, 20 to 88 years). Entry criteria required that patients have urge or mixed incontinence (with a predominance of urge), urge incontinence episodes of ≥ 10 per week, and ≥ 8 micturitions per day. The patient’s medical history and a urinary diary during the treatment-free baseline period confirmed the diagnosis of urge incontinence. Approximately 80% of patients had no prior pharmacological treatment for incontinence. Changes in weekly incontinence episodes, urinary frequency, and urinary void volume between placebo and active treatment groups are summarized in Table 4.

^ß  Comparison significant if p < 0.05
^à  Comparison significant if p ≤ 0.0167

Study 2 was a randomized, double-blind, study of OXYTROL 3.9 mg/day versus active and placebo controls conducted in 361 patients. The 12-week double-blind treatment included an OXYTROL dose of 3.9 mg/day, an active comparator, and placebo. The majority of patients were Caucasian (95%) and female (93%) with a mean age of 64 years (range, 18 to 89 years). Entry criteria required that all patients have urge or mixed incontinence (with a predominance of urge) and had achieved a beneficial response from the anticholinergic treatment they were using at the time of study entry. The average duration of prior pharmacological treatment was greater than 2 years. The patient’s medical history and a urinary diary during the treatment-free baseline period confirmed the diagnosis of urge incontinence. Changes in daily incontinence episodes, urinary frequency, and urinary void volume between placebo and active treatment groups are summarized in Table 5.

^£  Comparison significant if p < 0.05

Adhesion

Adhesion was periodically evaluated during the pivotal studies. Of the 4,746 OXYTROL evaluations in the trials, 20 (0.4%) were observed at clinic visits to have become completely detached and 35 (0.7%) became partially detached during routine clinic use. Similar to the pharmacokinetic studies, > 98% of the systems evaluated in the pivotal studies were assessed as being ≥ 75% attached and thus would be expected to perform as anticipated. 

16 How Supplied/Storage And Handling

How Supplied

Unit Dose: Heat sealed pouch containing 1 OXYTROL (oxybutynin transdermal system).

Each 39 cm² system imprinted with “OXYTROL 3.9 mg/day” contains 36 mg of oxybutynin for nominal delivery of 3.9 mg oxybutynin per day when dosed in a twice weekly regimen.

NDC 0023-6153-08 Patient Calendar Box of 8 Systems

Storage

Store at 20-25°C (68-77°F). [See USP controlled room temperature.] Protect from moisture and humidity. Do not store outside the sealed pouch. Apply immediately after removal from the protective pouch. Discard used OXYTROL in household trash in a manner that prevents accidental application or ingestion by children, pets, or others.

Keep out of reach of children.

17 Patient Counseling Information

 See FDA-Approved Patient Labeling (Patient Information and Instructions for Use)

Instructions for Use

Inform patients that OXYTROL should be applied to dry, intact skin on the abdomen, hip, or buttock and not be applied to areas that have been treated with oils, lotions or powders. The patch should not be exposed to sunlight. Contact with water while bathing, swimming, showering or exercising will not change the effect of OXYTROL.

A new application site should be selected with each new system to avoid re-application to the same site within 7 days. Inform patients to try to change the patch on the same 2 days each week and that the package of OXYTROL has a calendar checklist printed on the back to remind patients of their schedule. Inform patients to avoid rubbing the patch area during bathing, swimming, showering or exercising. Inform patients that details on use of the system are explained in the Patient Information Leaflet.

Inform patients to discard used OXYTROL in household trash in a manner that prevents accidental application or ingestion by children, pets, or others. Inform patients to keep out of reach of children.

Important Anticholinergic Adverse Reactions

Patients should be informed that anticholinergic (antimuscarinic) agents, such as OXYTROL, may produce adverse reactions related to anticholinergic pharmacological activity including:

• Urinary retention and constipation.
  
• Heat prostration (due to decreased sweating) when anticholinergics such as OXYTROL are used in a hot environment.
  
• Dizziness or blurred vision. Patients should be advised to avoid driving or operating heavy machinery until OXYTROL’s effects have been determined.
  
• Drowsiness that may be worsened by alcohol.
  
• Angioedema has been reported with oral oxybutynin use. Patients should be advised to promptly discontinue OXYTROL and seek immediate medical attention if they experience symptoms consistent with angioedema.

Distributed By:
Allergan USA, Inc.

Irvine, CA 92612

© 2017 Allergan. All rights reserved.

Oxytrol® is a registered trademark of Allergan Sales, LLC