Kentera: Uses, Dosage & Side Effects
Oxybutynin transdermal patch for the symptomatic treatment of urge incontinence and overactive bladder in adults
Kentera is a transdermal patch containing oxybutynin, an antimuscarinic (anticholinergic) agent used to treat the symptoms of overactive bladder (OAB) in adults. The patch delivers oxybutynin continuously through the skin at a rate of 3.9 mg per 24 hours over a 3- to 4-day wearing period. By bypassing first-pass hepatic metabolism, the transdermal formulation produces significantly lower levels of the active metabolite N-desethyloxybutynin (N-DEO) compared to oral oxybutynin, resulting in markedly reduced anticholinergic side effects — particularly dry mouth. Kentera is applied twice weekly to the abdomen, hip, or buttock, offering a convenient and well-tolerated treatment option for patients with urinary urgency, increased urination frequency, and urge urinary incontinence.
Quick Facts: Kentera
Key Takeaways
- Kentera is a transdermal oxybutynin patch that treats overactive bladder symptoms including urinary urgency, frequency, and urge incontinence by blocking muscarinic receptors on the bladder detrusor muscle.
- The transdermal delivery route bypasses first-pass liver metabolism, producing significantly less N-desethyloxybutynin and reducing the incidence of dry mouth to approximately 7–8% compared to 60–70% with oral immediate-release oxybutynin.
- The patch is applied twice weekly (every 3–4 days) to the abdomen, hip, or buttock, delivering a continuous dose of 3.9 mg oxybutynin per 24 hours throughout the wearing period.
- Application site skin reactions are the most frequently reported side effect; rotating the application site with each new patch reduces the risk of local irritation.
- Caution is advised in elderly patients who may be more susceptible to anticholinergic effects including cognitive impairment, confusion, and increased fall risk; the medication is contraindicated in urinary retention and uncontrolled narrow-angle glaucoma.
What Is Kentera and What Is It Used For?
Kentera contains the active substance oxybutynin, one of the most widely prescribed and extensively studied antimuscarinic medications for the treatment of overactive bladder. Oxybutynin belongs to the pharmacological class of muscarinic receptor antagonists (also known as anticholinergics or antimuscarinics), which are considered a first-line pharmacological treatment for OAB by major international urological societies including the American Urological Association (AUA), the European Association of Urology (EAU), and the International Continence Society (ICS). The unique aspect of Kentera is its transdermal delivery system, which provides oxybutynin through the skin in a controlled, continuous manner that significantly alters the drug’s pharmacokinetic profile compared to oral formulations.
Overactive bladder is a clinical syndrome defined by the International Continence Society (ICS) as urinary urgency, usually accompanied by increased daytime frequency and nocturia (nighttime urination), with or without urgency urinary incontinence, in the absence of urinary tract infection or other obvious pathology. OAB affects an estimated 12–17% of the adult population worldwide, with prevalence increasing significantly with age. The condition affects both men and women, though the presentation pattern may differ: women more commonly report urge incontinence, while men more frequently present with urgency and frequency alone. OAB has a profound impact on quality of life, affecting sleep, social interactions, physical activity, work productivity, and psychological well-being. Studies have demonstrated that untreated OAB is associated with higher rates of depression, anxiety, social isolation, and falls in the elderly.
The pathophysiology of overactive bladder involves involuntary contractions of the detrusor muscle — the smooth muscle layer of the bladder wall responsible for emptying the bladder during voiding. In healthy individuals, the detrusor remains relaxed during bladder filling, allowing the bladder to store urine at low pressure. In patients with OAB, the detrusor contracts spontaneously and inappropriately during the filling phase, producing the sensation of urgency and, if the contraction is strong enough, involuntary leakage of urine. These involuntary contractions are mediated primarily through the parasympathetic nervous system. Acetylcholine released from parasympathetic nerve endings binds to muscarinic receptors (predominantly the M3 subtype, with M2 also present) on the detrusor smooth muscle cells, triggering contraction.
Oxybutynin exerts its therapeutic effect by competitively blocking acetylcholine at muscarinic receptors, with particular affinity for the M3 subtype. By blocking muscarinic receptors on the detrusor muscle, oxybutynin reduces both the frequency and amplitude of involuntary bladder contractions during the filling phase. This results in increased functional bladder capacity, decreased urgency, reduced urinary frequency, and fewer episodes of urge incontinence. In addition to its antimuscarinic activity, oxybutynin has direct smooth muscle relaxant properties and local anesthetic effects on the bladder wall, which may contribute to its therapeutic efficacy.
The Kentera transdermal patch is a matrix-type patch that contains 36 mg of oxybutynin and delivers approximately 3.9 mg per 24 hours through the skin into the systemic circulation. Each patch is designed to be worn for 3 to 4 days before replacement. The critical pharmacological advantage of the transdermal route lies in its ability to bypass first-pass hepatic metabolism. When oxybutynin is taken orally, it undergoes extensive first-pass metabolism in the liver and gut wall by the cytochrome P450 enzyme CYP3A4, which converts a large proportion of the drug into its primary metabolite, N-desethyloxybutynin (N-DEO). N-DEO has similar antimuscarinic activity to the parent compound but achieves much higher plasma concentrations with oral dosing. Importantly, N-DEO is primarily responsible for the dose-limiting anticholinergic side effects, particularly dry mouth (xerostomia), which is the most common reason patients discontinue oral oxybutynin therapy. Clinical studies have demonstrated that the Kentera patch produces oxybutynin-to-N-DEO ratios of approximately 1:1, compared to approximately 1:10 with immediate-release oral oxybutynin. This dramatically reduced N-DEO exposure translates directly into a substantially lower incidence of dry mouth and improved treatment tolerability.
The Kentera transdermal delivery system achieves a critical pharmacokinetic benefit: by bypassing first-pass liver metabolism, it reduces the formation of N-desethyloxybutynin (N-DEO), the metabolite primarily responsible for anticholinergic side effects. Clinical trials showed dry mouth rates of approximately 7–8% with the patch versus 60–70% with immediate-release oral oxybutynin — a significant improvement that enhances long-term treatment adherence.
What Should You Know Before Taking Kentera?
Contraindications
Kentera must not be used in patients with the following conditions, as oxybutynin may worsen these conditions or pose serious risks:
- Urinary retention: Oxybutynin reduces bladder contractility and may worsen urinary retention. Patients who are unable to empty their bladder adequately must not use this medication. Conditions causing urinary retention include severe benign prostatic hyperplasia (BPH) with obstruction, urethral strictures, and neurogenic bladder with impaired voiding.
- Uncontrolled narrow-angle glaucoma: Antimuscarinic agents can increase intraocular pressure by dilating the pupil and blocking the drainage of aqueous humor. Kentera is contraindicated in patients with uncontrolled narrow-angle glaucoma. Patients with open-angle glaucoma who are being treated with appropriate therapy may use Kentera with caution and under ophthalmological monitoring.
- Severe gastrointestinal conditions: Kentera is contraindicated in patients with gastric retention, intestinal atony, or toxic megacolon, as the antimuscarinic effects of oxybutynin reduce gastrointestinal motility and may worsen these conditions.
- Myasthenia gravis: Antimuscarinic drugs may reduce the effectiveness of cholinesterase inhibitors used to treat myasthenia gravis and may worsen muscle weakness.
- Hypersensitivity: Patients with known hypersensitivity to oxybutynin or any of the patch excipients (including triacetin, acrylic adhesive, and other matrix components) must not use Kentera.
Warnings and Precautions
Antimuscarinic medications, including oxybutynin, have been associated with cognitive impairment and an increased risk of dementia in elderly patients, particularly with long-term use. The American Geriatrics Society Beers Criteria lists oxybutynin as potentially inappropriate for older adults. Monitor cognitive function regularly, especially in patients over 65, and consider alternative treatments if cognitive decline is observed.
Before starting Kentera, discuss the following conditions with your healthcare provider, as dose adjustment or closer monitoring may be necessary:
- Hepatic impairment: Oxybutynin is metabolized by the liver. Although transdermal delivery reduces first-pass metabolism, patients with significant hepatic impairment should be monitored carefully as plasma levels may be altered.
- Renal impairment: Caution should be exercised in patients with significant renal impairment, as drug and metabolite accumulation may occur.
- Gastrointestinal conditions: Oxybutynin may reduce gastrointestinal motility and should be used with caution in patients with hiatal hernia associated with reflux oesophagitis, ulcerative colitis, or other conditions where reduced motility may be harmful.
- Autonomic neuropathy: Patients with autonomic neuropathy may be more susceptible to both the therapeutic and adverse effects of antimuscarinic agents.
- Prostatic hypertrophy: While not absolutely contraindicated, oxybutynin should be used cautiously in men with benign prostatic hyperplasia due to the risk of precipitating or worsening urinary retention.
- Cardiovascular disease: Antimuscarinic agents may increase heart rate. Use with caution in patients with cardiac arrhythmias, heart failure, coronary artery disease, hypertension, or hyperthyroidism.
- Heat exposure: Oxybutynin may decrease sweating, which can increase the risk of heat-related illness. Patients should avoid strenuous exercise in hot environments and be vigilant for signs of heat stroke.
Pregnancy and Breastfeeding
Kentera should not be used during pregnancy unless clearly necessary. There are limited data on the use of oxybutynin in pregnant women. Animal studies have not demonstrated teratogenic effects at clinically relevant doses, but reproductive toxicity (reduced fertility and delayed growth) was observed at high doses in animal models. As a precautionary measure, oxybutynin should be avoided during pregnancy unless the potential benefit to the mother justifies the potential risk to the fetus. Women of childbearing potential should discuss contraception with their healthcare provider.
It is not known whether oxybutynin or its metabolites are excreted in human breast milk. Given the potential for adverse effects in the nursing infant — including sedation, reduced feeding, and anticholinergic effects — a decision should be made whether to discontinue breastfeeding or to discontinue Kentera, taking into account the benefit of breastfeeding for the child and the benefit of therapy for the mother.
Children and Adolescents
The safety and efficacy of the Kentera transdermal patch have not been established in children and adolescents under 18 years of age. Kentera is not recommended for paediatric use. While oral oxybutynin formulations may be used in children for certain neurogenic bladder conditions under specialist supervision, the transdermal patch has not been studied in this population and should not be substituted for oral formulations in paediatric patients.
Driving and Operating Machinery
Oxybutynin may cause drowsiness, dizziness, and blurred vision, particularly at the start of treatment or following dose adjustments. Patients should be advised not to drive or operate machinery until they know how Kentera affects them individually. These effects may be enhanced by concurrent use of alcohol, sedatives, or other medications that affect the central nervous system.
Application Site Care
The Kentera patch should be applied to clean, dry, smooth, intact skin on the abdomen, hip, or buttock. Avoid applying the patch to areas with cuts, abrasions, or skin irritation, as this may increase drug absorption and the risk of skin reactions. The patch should not be placed on the breasts, waistline (where tight clothing may cause the patch to detach), or on areas recently treated with creams, lotions, or powders, as these substances may affect patch adhesion. Rotating the application site with each new patch and avoiding the same site within 7 days helps to minimise application site reactions.
How Does Kentera Interact with Other Drugs?
Oxybutynin has several clinically significant drug interaction pathways that patients and prescribers should be aware of. Although the transdermal delivery route reduces some of the metabolic interactions associated with oral dosing, pharmacodynamic interactions remain important. Understanding these interactions is essential for safe and effective use of Kentera, particularly in elderly patients who frequently take multiple medications (polypharmacy).
Oxybutynin is metabolized primarily by the cytochrome P450 enzyme CYP3A4, both in the liver and in the intestinal wall. While transdermal delivery significantly reduces the extent of first-pass metabolism compared to oral administration, CYP3A4 remains involved in the systemic metabolism of oxybutynin after it enters the circulation through the skin. Co-administration with potent CYP3A4 inhibitors may increase plasma concentrations of oxybutynin, potentially enhancing both therapeutic and adverse effects.
The most important drug interactions to be aware of are summarised in the following table:
| Drug / Drug Class | Type of Interaction | Clinical Significance | Recommendation |
|---|---|---|---|
| Other anticholinergics (e.g. tiotropium, ipratropium, tolterodine, solifenacin) | Pharmacodynamic (additive) | Increased anticholinergic side effects: dry mouth, constipation, urinary retention, blurred vision, cognitive impairment | Avoid combination if possible; monitor closely if unavoidable |
| CYP3A4 inhibitors (e.g. ketoconazole, itraconazole, erythromycin, clarithromycin, grapefruit juice) | Pharmacokinetic (enzyme inhibition) | Increased oxybutynin plasma levels; enhanced anticholinergic effects | Use with caution; monitor for increased side effects |
| Cholinesterase inhibitors (e.g. donepezil, rivastigmine, galantamine) | Pharmacodynamic (antagonistic) | Oxybutynin may reduce the efficacy of cholinesterase inhibitors used for dementia; cholinesterase inhibitors may reduce oxybutynin efficacy | Avoid combination; consider alternative OAB treatment (e.g. mirabegron) |
| Opioid analgesics (e.g. codeine, tramadol, morphine, oxycodone) | Pharmacodynamic (additive) | Enhanced sedation, constipation, and urinary retention | Use with caution; monitor bowel and bladder function |
| CNS depressants (e.g. benzodiazepines, sedating antihistamines, alcohol) | Pharmacodynamic (additive) | Increased drowsiness, dizziness, and risk of falls | Avoid alcohol; use CNS depressants with caution; monitor for excessive sedation |
| Metoclopramide / domperidone | Pharmacodynamic (antagonistic) | Oxybutynin may reduce the prokinetic effects of metoclopramide and domperidone | Monitor gastrointestinal symptoms; consider alternatives |
| Potassium chloride (solid oral forms) | Pharmacodynamic (indirect) | Reduced GI motility from oxybutynin may increase exposure time of potassium to GI mucosa, increasing risk of ulceration | Use liquid potassium preparations or monitor for GI symptoms |
The interaction between antimuscarinic drugs and cholinesterase inhibitors deserves particular emphasis. Patients with dementia who are taking medications such as donepezil, rivastigmine, or galantamine should generally not use oxybutynin, as the two drug classes have directly opposing mechanisms of action. Cholinesterase inhibitors work by increasing acetylcholine levels in the brain to improve cognitive function, while antimuscarinics such as oxybutynin block acetylcholine receptors. This pharmacological conflict may reduce the efficacy of dementia treatment and could worsen cognitive decline. International guidelines, including the American Geriatrics Society Beers Criteria, specifically flag this combination as potentially inappropriate. In such patients, the beta-3 adrenergic agonist mirabegron is often recommended as an alternative OAB treatment that lacks anticholinergic effects.
Patients using Kentera should inform their healthcare provider about all medications they are taking, including prescription drugs, over-the-counter medicines, herbal supplements, and vitamin preparations. Herbal products such as St. John’s wort (Hypericum perforatum), a potent CYP3A4 inducer, may reduce oxybutynin plasma levels and potentially decrease its effectiveness. Conversely, herbal products with anticholinergic properties (such as belladonna alkaloids) may enhance anticholinergic side effects when used concurrently.
Patients with overactive bladder, particularly the elderly, often take multiple medications. The cumulative anticholinergic burden from combining several medications with anticholinergic properties — including antidepressants (tricyclics, paroxetine), first-generation antihistamines, antipsychotics, and antispasmodics — can significantly increase the risk of adverse effects. Healthcare providers should assess the total anticholinergic burden using validated tools such as the Anticholinergic Cognitive Burden (ACB) scale before prescribing Kentera.
What Is the Correct Dosage of Kentera?
Kentera should always be used exactly as your doctor has instructed. The dosing regimen is straightforward: one patch applied twice weekly, changed every 3 to 4 days (for example, applying a new patch on Sunday and Wednesday, or on Monday and Thursday). This consistent, twice-weekly schedule is designed to maintain steady-state plasma concentrations of oxybutynin throughout the treatment period, providing continuous symptom relief.
Adults
Standard Adult Dose
Apply one Kentera 3.9 mg/24h transdermal patch to the abdomen, hip, or buttock twice weekly (every 3–4 days). Only one patch should be worn at a time. The patch should be replaced at approximately the same time on each designated day to maintain consistent drug delivery.
| Patient Group | Dose | Frequency | Special Instructions |
|---|---|---|---|
| Adults | One patch (3.9 mg/24h) | Twice weekly (every 3–4 days) | Rotate application sites; apply to abdomen, hip, or buttock |
| Elderly (≥65 years) | One patch (3.9 mg/24h) | Twice weekly (every 3–4 days) | Same dose; monitor for anticholinergic side effects and cognitive changes |
| Hepatic impairment | One patch (3.9 mg/24h) | Twice weekly (every 3–4 days) | Use with caution; monitor for increased side effects |
| Renal impairment | One patch (3.9 mg/24h) | Twice weekly (every 3–4 days) | Use with caution; monitor for increased side effects |
| Children (<18 years) | Not recommended | — | Safety and efficacy not established in paediatric population |
How to Apply the Patch
Proper application technique is essential for effective drug delivery and minimising skin reactions. Follow these steps when applying a new Kentera patch:
- Remove the old patch (if one is in place). Fold the used patch in half with the adhesive side inward and dispose of it safely out of reach of children and pets, as it still contains residual oxybutynin.
- Choose a new application site on the abdomen, hip, or buttock. The site should be clean, dry, and free of cuts, rashes, or irritation. Do not apply to the same site used in the previous 7 days.
- Do not use lotions, oils, powders, or creams on the application area, as these may affect patch adhesion and drug absorption.
- Open the sachet and remove the patch. Peel off the protective liner to expose the adhesive surface.
- Press the patch firmly onto the skin for at least 10 seconds, ensuring good contact around the edges. Smooth the patch with your hand.
- Wash your hands after applying the patch.
You may shower, bathe, or swim while wearing the Kentera patch. The adhesive is designed to withstand normal water exposure. However, avoid prolonged exposure to hot water, saunas, or hot tubs, as excessive heat may increase drug absorption. If a patch falls off prematurely, apply a new one to a different site and continue with your regular replacement schedule.
Missed Dose
If you forget to change your patch on the scheduled day, apply a new patch as soon as you remember and continue with your regular twice-weekly schedule. Do not apply two patches at once to make up for a missed dose. If the patch has been off for an extended period, you may notice a temporary return of OAB symptoms until steady-state plasma levels are re-established, which typically occurs within the first application period.
Overdose
Overdose with oxybutynin may produce severe anticholinergic effects including restlessness, tremor, irritability, convulsions, delirium, hallucinations, flushing, fever, nausea, vomiting, tachycardia, hypotension or hypertension, respiratory failure, paralysis, and coma. In case of suspected overdose, remove the patch immediately and seek emergency medical attention. Treatment is supportive and symptomatic. Physostigmine may be considered under specialist guidance for severe anticholinergic toxicity.
Accidental application of more than one patch at a time, or ingestion of the patch by children or pets, can lead to oxybutynin overdose. Transdermal patches should always be stored and disposed of safely. If a child or pet accidentally ingests or applies a patch, seek emergency medical attention immediately. After removing the patch in an overdose situation, oxybutynin levels will decline gradually as the drug is eliminated from the body, but monitoring should continue for at least 24 hours due to the sustained-release nature of transdermal delivery.
What Are the Side Effects of Kentera?
Like all medicines, Kentera can cause side effects, although not everybody gets them. The transdermal formulation was specifically designed to improve the tolerability profile of oxybutynin by reducing exposure to the metabolite N-desethyloxybutynin (N-DEO), which is the main driver of systemic anticholinergic side effects with oral dosing. Clinical trials have demonstrated that the most significant tolerability advantage of the Kentera patch over oral oxybutynin is the dramatically reduced incidence of dry mouth, which dropped from approximately 60–70% with immediate-release oral oxybutynin to approximately 7–8% with the transdermal patch.
The trade-off for improved systemic tolerability is the introduction of local application site reactions, which are the most frequently reported adverse events with the Kentera patch. These reactions are generally mild to moderate in severity and typically resolve within days of patch removal. Rotating the application site with each new patch, as recommended, helps minimise the occurrence and severity of local skin reactions.
The following side effects have been reported during clinical trials and post-marketing surveillance, organised by frequency:
Very Common (affects more than 1 in 10 people)
Frequency: >10%
- Application site itching (pruritus)
- Application site redness (erythema)
Common (affects 1 to 10 in 100 people)
Frequency: 1–10%
- Dry mouth (xerostomia)
- Dizziness
- Headache
- Constipation
- Diarrhoea
- Nausea
- Abdominal pain
- Application site rash or vesicles
- Blurred vision
- Dysuria (painful urination)
- Urinary tract infection
Uncommon (affects 1 to 10 in 1,000 people)
Frequency: 0.1–1%
- Upper respiratory tract infection
- Drowsiness / somnolence
- Insomnia
- Nervousness / anxiety
- Palpitations / tachycardia
- Flushing
- Back pain
- Urinary retention
- Dry eyes
- Flatulence / dyspepsia
Rare (affects fewer than 1 in 1,000 people)
Frequency: <0.1%
- Confusion / cognitive impairment
- Hallucinations (particularly in elderly patients)
- Memory impairment
- Severe allergic / hypersensitivity reactions
- Angioedema
- Seizures
- Severe application site skin reactions
Not Known (frequency cannot be estimated)
Reported in post-marketing surveillance
- Heat stroke (due to decreased sweating)
- Rhabdomyolysis (associated with anticholinergic syndrome)
- Psychotic disorder
- Cycloplegia (paralysis of accommodation)
- Mydriasis (pupil dilation)
Application site reactions deserve particular attention as they are the most common reason for treatment discontinuation with the Kentera patch. In clinical trials, approximately 14% of patients reported application site pruritus (itching) and 8% reported application site erythema (redness). These reactions are generally mild and self-limiting, resolving within a few days of removing the patch from the affected area. Strategies to minimise application site reactions include: rotating between at least four different sites on the abdomen, hip, and buttock; ensuring the skin is completely dry before application; avoiding areas recently exposed to skin care products; and ensuring the patch is applied smoothly without wrinkles.
Central nervous system effects including drowsiness, dizziness, confusion, and hallucinations are more common in elderly patients and those taking other medications with anticholinergic or CNS-depressant properties. These effects are generally dose-related and may be more pronounced during the initial weeks of treatment. If significant CNS effects occur, your doctor may recommend discontinuing Kentera and switching to an alternative treatment.
If you experience any side effects not listed here, or if any side effects become severe or troublesome, contact your doctor or pharmacist. You can also report side effects directly to your national medicines regulatory authority to help ensure ongoing safety monitoring of this medication.
How Should You Store Kentera?
Proper storage of the Kentera transdermal patch is important to ensure the medication remains effective and safe throughout its shelf life. Transdermal patches are complex drug delivery systems that rely on the integrity of the adhesive matrix and the chemical stability of the active ingredient for proper drug delivery. Exposure to inappropriate storage conditions can compromise both the adhesive properties of the patch and the stability of oxybutynin within the matrix.
Follow these storage guidelines to maintain the quality and effectiveness of your Kentera patches:
- Temperature: Store at room temperature, below 25°C (77°F). Do not refrigerate or freeze the patches, as extreme temperatures can alter the adhesive properties and drug release characteristics.
- Packaging: Keep each patch in its original sealed sachet until you are ready to use it. The sachet protects the patch from moisture and environmental degradation.
- Light and heat: Protect from direct sunlight and heat sources. Do not store in areas subject to high temperatures, such as near radiators, in cars during summer, or in direct sunlight on windowsills.
- Children and pets: Both used and unused patches must be stored out of the sight and reach of children and pets. Used patches still contain residual oxybutynin that could be harmful if ingested or applied accidentally.
- Disposal: Fold used patches in half with the adhesive side inward. Dispose of them safely in household waste, ensuring they cannot be accessed by children or pets. Some pharmacies accept used patches for safe disposal.
- Expiry date: Do not use Kentera after the expiry date stated on the sachet and carton. The expiry date refers to the last day of that month.
Do not use a Kentera patch if the sachet seal is broken, if the patch appears damaged or discoloured, or if the adhesive surface appears dry or compromised. If you have any doubts about the condition of a patch, do not apply it and use a new one instead. Do not dispose of medications via wastewater or household waste unless instructed to do so; ask your pharmacist about proper disposal methods in your country to protect the environment.
What Does Kentera Contain?
Understanding the composition of the Kentera patch is important for identifying potential allergens and understanding how the drug delivery system works. The Kentera transdermal system is a matrix-type patch, meaning the active substance is dispersed uniformly throughout an adhesive matrix rather than contained in a separate drug reservoir. This design has advantages in terms of manufacturing consistency, lower risk of dose dumping if the patch is damaged, and a thinner, more comfortable patch profile.
Active Ingredient
Each Kentera transdermal patch contains 36 mg of oxybutynin. The total drug content exceeds the amount delivered during the wearing period; this excess is necessary to maintain the concentration gradient that drives drug absorption through the skin at the target delivery rate of 3.9 mg per 24 hours. At the end of the wearing period (3–4 days), the patch still contains residual oxybutynin, which is why proper disposal is important.
Inactive Ingredients (Excipients)
The patch consists of three functional layers:
- Backing film: A flexible, occlusive polyester/ethylene-vinyl acetate (EVA) laminate that forms the outer surface of the patch. This layer is impermeable to oxybutynin and protects the adhesive matrix from the environment.
- Adhesive matrix: An acrylic adhesive containing oxybutynin dispersed with triacetin (glycerol triacetate) as a solubilising agent and permeation enhancer. The acrylic adhesive provides skin contact and drug delivery simultaneously.
- Release liner: A siliconised polyester film that covers the adhesive surface and is removed before application. This liner is discarded during use and does not remain on the skin.
The Kentera patch does not contain latex. Patients with latex allergies can safely use this product. The patch is also free from preservatives and does not contain any colouring agents. The active surface area of the patch is 39 cm². Patients with known allergies to acrylic adhesives or triacetin should inform their healthcare provider before using Kentera, as these components could potentially cause contact dermatitis or allergic skin reactions at the application site.
Frequently Asked Questions About Kentera
Kentera is a transdermal (skin) patch containing oxybutynin, used to treat the symptoms of overactive bladder (OAB) in adults. OAB is characterised by a sudden, compelling urge to urinate (urgency), needing to urinate more frequently than normal (increased frequency), and involuntary leakage of urine associated with urgency (urge urinary incontinence). Kentera works by relaxing the bladder muscle through blocking muscarinic receptors, which reduces involuntary bladder contractions and increases the amount of urine the bladder can hold comfortably.
The main difference is the route of delivery and its impact on side effects. When oxybutynin is taken by mouth, it undergoes extensive first-pass metabolism in the liver, converting a large proportion to the metabolite N-desethyloxybutynin (N-DEO), which causes most of the anticholinergic side effects, especially dry mouth. The Kentera transdermal patch delivers oxybutynin through the skin directly into the bloodstream, bypassing the liver. This produces much lower N-DEO levels, resulting in significantly less dry mouth (approximately 7–8% versus 60–70% with oral formulations) while maintaining comparable efficacy in reducing OAB symptoms.
Yes, the Kentera patch is designed to stay in place during normal daily activities, including showering, bathing, and swimming. The adhesive is water-resistant and should maintain good skin contact during routine water exposure. However, you should avoid prolonged soaking in hot water, saunas, or hot tubs, as excessive heat can increase drug absorption through the skin and may alter the delivery profile. If a patch falls off due to water exposure or other activity, apply a new patch to a different site and continue your regular replacement schedule.
Kentera can be used by elderly patients, but extra caution is warranted. Older adults are generally more sensitive to the anticholinergic effects of oxybutynin, which can include confusion, drowsiness, memory problems, increased risk of falls, constipation, and urinary retention. Long-term use of anticholinergic medications has been associated with an increased risk of cognitive decline and dementia in observational studies. The American Geriatrics Society Beers Criteria lists oxybutynin as potentially inappropriate for older adults. Doctors should regularly assess cognitive function in elderly patients using Kentera and consider alternative treatments (such as mirabegron) if cognitive effects are detected.
Mild skin reactions at the application site, such as itching and redness, are common with the Kentera patch and are usually temporary. To minimise irritation, rotate between at least four different application sites on the abdomen, hip, and buttock, and wait at least 7 days before reusing a site. Make sure the skin is clean, dry, and free of lotions or creams before applying the patch. If you develop a persistent or severe skin reaction (such as blistering, intense burning, or rash spreading beyond the patch area), remove the patch and contact your healthcare provider. They may recommend a different treatment approach if skin reactions are intolerable.
Oxybutynin from the Kentera patch begins to be absorbed into the bloodstream within hours of application, and steady-state plasma levels are typically achieved during the first application period (3–4 days). However, the full clinical benefit may take several weeks to become apparent, as the bladder gradually responds to the sustained antimuscarinic effect. Many patients notice some improvement in urgency and frequency within the first 1–2 weeks, but doctors generally recommend assessing the effectiveness of treatment after at least 4–8 weeks of consistent use before making any decisions about dose adjustments or treatment changes.
References
- European Medicines Agency (EMA). Kentera – Summary of Product Characteristics. Last updated 2024. Available from: www.ema.europa.eu
- Dmochowski RR, Davila GW, Zinner NR, et al. Efficacy and safety of transdermal oxybutynin in patients with urge and mixed urinary incontinence. Journal of Urology. 2002;168(2):580–586.
- Davila GW, Daugherty CA, Sanders SW; Transdermal Oxybutynin Study Group. A short-term, multicenter, randomized double-blind dose titration study of the efficacy and anticholinergic side effects of transdermal compared to immediate release oral oxybutynin treatment of patients with urge urinary incontinence. Journal of Urology. 2001;166(1):140–145.
- Gormley EA, Lightner DJ, Burgio KL, et al. Diagnosis and Treatment of Overactive Bladder (Non-Neurogenic) in Adults: AUA/SUFU Guideline Amendment 2019. Journal of Urology. 2019;202(3):558–563.
- Lightner DJ, Gomelsky A, Souter L, Vasavada SP. Diagnosis and Treatment of Overactive Bladder (Non-Neurogenic) in Adults: AUA/SUFU Guideline Amendment 2024. Journal of Urology. 2024;212(1):18–25.
- European Association of Urology (EAU). Guidelines on Non-Neurogenic Female Lower Urinary Tract Symptoms. 2024. Available from: uroweb.org/guidelines
- Coupland CAC, Hill T, Dening T, Morriss R, Moore M, Hippisley-Cox J. Anticholinergic Drug Exposure and the Risk of Dementia: A Nested Case-Control Study. JAMA Internal Medicine. 2019;179(8):1084–1093.
- By the 2023 American Geriatrics Society Beers Criteria Update Expert Panel. American Geriatrics Society 2023 Updated AGS Beers Criteria for Potentially Inappropriate Medication Use in Older Adults. Journal of the American Geriatrics Society. 2023;71(7):2052–2081.
- Chapple CR, Khullar V, Gabriel Z, Muston D, Bitoun CE, Weinstein D. The effects of antimuscarinic treatments in overactive bladder: an update of a systematic review and meta-analysis. European Urology. 2008;54(3):543–562.
- World Health Organization (WHO). WHO Model List of Essential Medicines – 23rd List, 2023. Geneva: World Health Organization; 2023.
Editorial Team
Medical Content
iMedic Medical Editorial Team – Specialists in Urology and Clinical Pharmacology
Medical Review
iMedic Medical Review Board – Independent panel of board-certified physicians
Evidence Standard
Level 1A – Based on systematic reviews and meta-analyses of randomized controlled trials
Guidelines Followed
EMA SmPC, AUA/SUFU Guidelines, EAU Guidelines, ICS Standards, AGS Beers Criteria
This article was written by licensed medical professionals and reviewed by an independent medical review board. All medical claims are supported by peer-reviewed evidence. This content is updated regularly to reflect the latest clinical guidelines and evidence. Last reviewed: .