Antimuscarinic drugs for Overactive Bladder (OAB)

Take account of

• coexisting conditions (for example, poor bladder emptying, constipation, glaucoma)
• use of other existing medication affecting the total antimuscarinic load
• risk of adverse effects.

Discuss with patient

• the likelihood of success and associated common adverse effects
• the frequency and route of administration
• that some adverse effects such as dry mouth and constipation may indicate that treatment is starting to have an effect
• that they may not see the full benefits until they have been taking the treatment for 4 weeks.
• Consider bladder training programme in combination with an OAB drug if frequency is a troublesome symptom.

Pharmacological Treatments

First line antimuscarinics

• Oxybutynin (IR)
  • initially 5 mg bd
  • increase according to response upto qds 
• Tolterodine (IR)
  • 2 mg twice daily, reduce to 1 mg twice daily if necessary to minimise side effects
  • impaired liver function or severe renal impairment (eGFR ≤30mL/min) or to minimise side effects prescribe 1mg BD
  • Generally better tolerated than oxybutynin and does not require dose titration
• Trospium modified release (MR)
  • 60mg taken once daily (for older patients)
  • may have fewer CNS side-effect esp. in elderly
  • C/I severe hepatic impairment
  • Not recommended for use in renally impaired patients (10- 30mL/min/1.73m2 )
• Tolterodine MR
  • 4mg once daily
  • Reduce dose to 2mg od if impaired liver function or severely impaired renal function (GFR ≤ 30 ml/min) is present 

Second line 

• Mirabegron
  • 50mg od  
  • Avoid if eGFR<15ml/min/1.73m2
  • Reduce to 25mg od if eGFR 15-29ml/min/1.73m
  • contraindicated in patients with severe uncontrolled hypertension
• Transdermal oxybutynin
  • one patch twice weekly
  • apply to clean, dry unbroken skin on the abdomen, hip or buttock
  • first line untolerable/uncontrolled hypertension/swallowing difficulties
• Trospium IR
  • 20mg bd
  • reduce dose to 20mg od or 20mg on alternate days if eGFR is ≤ 10-30mL/min
  • not recommended in severe hepatic impairment.
• Tolterodine MR
• Oxybutynin MR
• Solifenacin
  •  5 mg once daily, increased if necessary to 10 mg once daily
  • No more than the initial daily dose, according to body-weight, with concurrent use of potent inhibitors of CYP3A4
  • Severe renal impairment (creatinine clearance ≤ 30 ml/min) and moderate hepatic impairment with a maximum daily dose 5mg od

DO NOT use:

• Flavoxate, propantheline and imipramine
• Immediate release (IR) oxybutynin in frail older patients
• Duloxetine should not be used in the treatment of OAB but may be initiated by specialists for stress incontinence

Nocturnal Symptoms (nocturia) 

• Amitriptyline 25 to 50mg orally at bedtime (unlicensed in adults)
• imipramine 50-75mg orally at bedtime (unlicensed in adults)
• desmopressin (unlicensed)-  to reduce nocturia in patients who find it a troublesome symptom if other medical causes have been excluded and they have not benefited from other treatments. Use particular caution in patients with cystic fibrosis and avoid in those over 65 years with cardiovascular disease or hypertension. Symptomatic hyponatraemia is more likely to occur soon after treatment initiation. Pre-treatment and early post-treatment (3 days after the first dose) serum sodium monitoring is recommended. If serum sodium is reduced to below the normal range, stop desmopressin treatment.

Urinary retention due to prostatic hyperplasia (BPH) in men

Treatment of Lower Urinary Tract Symptoms (LUTS)

• First choice Tamsulosin MR 400mcg orally once daily after food
• Alfusosin 10mg orally once daily. For acute urinary retention associated with BPH for men over 65 years, 10mg once daily for 2-3 days during catheterisation and for one day after removal: max 4 days. May need to consider continuing if urinary symptoms persist. An antimuscarinic drug should be considered as well as an alpha blocker in men who still have storage symptoms after treatment with an alpha blocker alone

Fluid intake

Consider advising modification of high or low fluid intake. Both excessive and inadequate fluid intake may lead to lower urinary tract symptoms; this should be considered on an individual basis.

Lifestyle advice may include:

• A trial of caffeine reduction - there is some evidence that caffeine reduction leads to less urgency and frequency when used in addition to bladder training
• Smoking cessation
• Weight reduction if body mass index is 30 kg/m 2 or greater

Prescribe the lowest recommended dose when starting a new OAB drug to reduce the likelihood of side-effects.