Incontinence

Question 1

What are the 4 types of incontinence ?

Answer 1

Question 2

How is the bladder innervated (Receptors for drug action ?).

Answer 2

-Autonomic innervation of the bladder includes the muscarinic M3 cholinceptorin the parasympathetic nervous system.

-For the sympathetic nervous system the B3-adrenoceptor subtype relaxes the bladder

-The a1-adrenoceptor is involved in contraction of the bladder neck.

Question 3

Name a frequently prescirbes Cholinergic Muscarinic Antagonists

Answer 3

oxybutynin

Question 4

How do Cholinergic Muscarinic Antagonists work?

Answer 4

In urinary incontinence produced by an overactive bladder, a muscarinic cholinergic antagonist blocks the parasympathetic NS, lowering pressure, increasing bladder capacity and reducing the frequency of urination. They may also be helpful in bed wetting in children and with paraplegics patients. Probably the most well known is oxybutynin. However, systemic muscarinic antagonism may also produce blurred vision, constipation and dry mouth. Analogues include darifenacin, designed to be more selective for the bladder with less effect on the CNS while trospium, being renally excreted, produces higher drug concentrations in the bladder.

Question 5

What is the mechanism of action of B2 antagonist

Answer 5

. It relaxes the detrusor muscle in the bladder increasing bladder capacity in over active bladder, reducing frequency. Its potential adverse effect is to induce hypertension. Primary care prescribing data would suggest a marked increase in the use of mirabegron over the last few years, although the other drugs in major use are all muscarinic receptor antagonist.

Question 6

Name a B2 agonist

Answer 6

Mirabegron

Question 7

Name a α1-adrenoceptor antagonist

Answer 7

Tamulosin

Question 8

What medication is used for urinary retension for postate enlargement ?

Answer 8

α1-adrenoceptor antagonist eg Tamulosin

Question 9

What is the mechanism of action of α1-adrenoceptor antagonist

Answer 9

Antagonism of the a1A receptor in the prostate and bladder neck induces relaxation and can be used in prostatic benign hypertrophy or with kidney stones. Tamsulosin, related to the anti-hypertensive doxazosin, is the agent of choice.

Question 10

What drugs can induce bladder damage ?

Answer 10

Two important examples are the anti-cancer drug cyclophosphamide which generates a toxic liver by-product acreolin which can induce haemorraghic nephritis, reduced by hydration during drug infusion.

While ketamine can induce cystitis and bladder necrosis which maybe severe enough to require a bladder transplant.