Antimuscarinics, genitourinary

Question 1

1) Name the 2 p-drugs in the antimuscarinics class which have genitourinary uses.

Answer 1

1) Oxybutinin and Tolterodine

Question 2

Give the main common indication for the use of antimuscarinics for genitourinary uses.

Answer 2

To reduce urinary frequency, urgency and urge incontinence in overactive bladder, as a first line pharmacological treatment if bladder training is ineffective.

Question 3

1) What do antimuscarinic drugs bind to?
2) What do antimuscarinic drugs do once bound?
3) What type of control is contraction of the detrusor muscle under?
4) What is the overall effect of antimuscarinics on the bladder?

Answer 3

1) Muscarinic receptors.
2) They act as a competitive inhibitor of acetylcholine.
3) Contraction of smooth muscle of the bladder is under parasympathetic control.
4) They promote bladder relaxation, increasing bladder capacity.

Question 4

1) Through use of antimuscarinics, what symptoms of an overactive bladder may be reduced?
2) What is the main muscarinic receptor subtype found in the bladder? So, which antimuscarinics are most useful?

Answer 4

1) Urinary frequency, urgency and urge incontinence.
2) M3 receptors are the main muscarinic receptor subtype in the bladder, so antimuscarinics useful in treating overactive bladder tend to be relatively selective for the M3 receptor.

Question 5

1) What is a common side effect of genitourinary antimuscarinics?
2) Name 3 other classic side effects of antimuscarinics.
3) What may occur when taking antimuscarinics if there is bladder outflow obstruction?

Answer 5

1) Dry mouth.
2) Tachycardia, constipation and blurred vision.
3) Urinary retention.

Question 6

1) When are antimuscarinics contraindicated?
2) Therefore, what is an important part of the assessment before prescribing treatment for an overactive bladder?
3) In which 2 groups of people can CNS side effects (drowsiness and confusion) of antimuscarinics be particularly problematic?
4) In which 3 groups of people should antimuscarinics be used with caution in?

Answer 6

1) In the context of UTI.
2) Urinalysis.
3) The elderly and especially patients with dementia.
4) Patients susceptible to angle-closure glaucoma, arrhythmias or urinary retention.

Question 7

1) Why should antimuscarinics be used with caution in patients at risk of angle-closure glaucoma?
2) When are adverse effects of antimuscarinics more pronounced?

Answer 7

1) Because in these patients, they can precipitate a dangerous rise in intraocular pressure.
2) When they are combined with other drugs that have antimuscarinic effects, such as TCAs.

Question 8

1) When should antimuscarinics be prescribed for urge incontience?
2) For urge incontinence, what is recommended as first line therapy?
3) When should you review a patient who has been commenced on antimuscarinics for urge incontinence?

Answer 8

1) After an adequate trial of bladder retraining.
2) Immediate-release oxybutynin - 5mg orally every 8 or 12 hours.
3) Within a month of starting the therapy in order to review response and side effects.