Precautions and Warnings

Frail elderly patients may be more sensitive to the effects of oxybutynin and should be treated with caution.

Use with caution in patients with renal impairment.

Use with caution in patients with hepatic impairment.
Patients with hepatic impairment should be monitored during treatment.

Pregnancy - see Pregnancy section

Before treatment is initiated, other possible causes of urinary frequency should be investigated (such as heart failure or renal disease).

Urinary tract infections should be treated appropriately with antibiotics.

Use with caution in patients with clinically significant bladder outflow obstruction due to the risk of urinary retention.

Oxybutynin may cause drowsiness, blurred vision, dizziness and fatigue. Patients should be warned of these effects and advised to exercise caution when performing skilled tasks such as driving or machinery operation. They should also be advised that alcohol may enhance these effects.

The following precautions have been noted with the oral administration of oxybutynin, however they have not been observed in clinical trials for oxybutynin patch.

Reduced gastrointestinal motility
Gastroesophageal reflux
Hiatus hernia (may be aggravated)
Autonomic neuropathy

Use with caution in patients with autonomic neuropathy, cognitive impairment or Parkinson's disease.

When administered in a hot environment, oxybutynin can cause heat prostration (fever and heat stroke due to decreased sweating).

The following conditions may be aggravated by oxybutynin treatment:
Hyperthyroidism
Congestive cardiac failure
Coronary artery disease
Cardiac arrhythmia
Tachycardia
Hypertension
Prostatic hypertrophy

Oxybutynin may cause suppressed secretion of saliva which can lead to dental caries, parodontosis or oral candidiasis.

Use in Porphyria

The Norwegian Porphyria Centre classifies oxybutynin as being 'possibly porphyrinogenic'.

Pregnancy and Lactation

Pregnancy

Oxybutynin should only be used during pregnancy if considered essential and there is no safer alternative.

At the time of writing, no reports of the use of oxybutynin in human pregnancy were available. Animal studies have shown minor reproductive toxicity.
However, Briggs (2011) and Schaefer (2007) suggest that based on animal data, that the risk to the foetus is low.

The use of all medication in pregnancy should be avoided whenever possible; particularly in the first trimester. Non-drug treatments should also be considered. When essential, a medication with the best safety record over time should be chosen, employing the lowest effective dose for the shortest possible time. Polypharmacy should be avoided. Teratogens taken in the pre-embryonic period, often quoted as lasting until 14 to 17 days post-conception, are believed to have an all-or-nothing effect. Where drugs have a short half-life, and when the date of conception is certain, this may allow women to be reassured where drug exposure has occurred within this time frame. Further advice may be available from the UK National Teratology Information Service (NTIS) and through ToxBase, available via password on the internet ( www.toxbase.org ) or if this is unavailable at the backup site ( www.toxbasebackup.org ).

Lactation

Use oxybutynin with caution in breastfeeding.

A small amount of oxybutynin is excreted in human breast milk. At the time of writing there is limited published information regarding the use of oxybutynin during breastfeeding, therefore the effect on the newborn/infant is unknown. Schaefer (2007) suggests that its use for bladder incontinence is acceptable, although antimuscarinics may reduce lactation. The UK drugs in Lactation Advisory Service suggests oxybutynin may be used with caution in breastfeeding provided the infant is monitored for anticholinergic affects, e.g. urinary retention, colic, constipation and poor weight gain.

Neonates, infants born prematurely, those with low birth weight, those with an unstable gastrointestinal function or who have serious illnesses may require special consideration. For any infant, if a drug is prescribed to the nursing mother, it should be at the lowest practical dose and for the shortest time. When drug administration is unavoidable and breastfeeding is to continue, minimisation of exposure of the infant to the drug may sometimes be achieved by timing the maternal doses to just after a feeding episode. Infants exposed to drugs via breast milk should be monitored for unusual signs or symptoms. Interactions between the drug received by the infant from the mother's milk and medication prescribed for the infant should also be considered, for example, when the drug given to the infant may prevent metabolism of the drug received via breast milk.
Specialist advice is available from the UK Drugs in Lactation Advisory Service at https://www.midlandsmedicines.nhs.uk/content.asp?section=6&subsection=17&pageIdx=1

Presentation

Transdermal patch releasing a nominal 3.9 mg of oxybutynin every 24 hours.

The area of the patch is 39 centimetres squared and each patch contains 36 mg oxybutynin.

Drugs List

KENTERA 3.9mg/24hour patch

oxybutynin 3.9mg/24hour patch

Therapeutic Indications

Uses

Symptomatic treatment of urge incontinence and/or increased urinary frequency and urgency, as may occur in patients with unstable bladder.

Dosage

Adults

Apply one patch twice weekly (every 3 to 4 days).

Elderly

Use with caution in elderly patients. This is because elderly patients may be more sensitive to the effects of centrally acting anticholinergics and show pharmacokinetic differences.

Children

Not recommended for use in children as no studies have been performed.

Adolescents

Not recommended for use in adolescents as no studies have been performed.

Patients with Renal Impairment

Use with caution in patients with renal impairment.

Patients with Hepatic Impairment

Use with caution in patients with hepatic impairment.

Patients with hepatic impairment should be monitored during treatment.

Administration

For topical administration.

The patch should be applied to dry intact skin on the abdomen, hip or buttock. After the patch is removed from the protective sachet, it must be applied immediately.

A new application site should be selected when each new patch is applied in order to avoid repeated application to the same site within 7 days.

Handling

Active ingredients remaining in the patch after use may have a harmful effect if reaching the aquatic environment. Advise patients that after removal, the patch should be folded in half with the adhesive side inwards, placed in the original sachet and discarded out of the reach of children. used patches should not be placed in liquid waste disposal systems or flushed down the toilet.

Contraindications

Children under 18 years
Narrow-angle glaucoma or shallow anterior chamber
Myasthenia gravis
Urinary retention
Gastrointestinal obstructive disorder
Paralytic ileus
Intestinal atony
Severe ulcerative colitis
Toxic megacolon
Acute porphyria
Breastfeeding - see Lactation section