Bladder medications

Anticholinergic medications for detrusor overactivity

The body of the detrusor is comprised of smooth muscle that contains muscarinic receptors, which bind acetylcholine and initiate muscle contractions. Muscarinic anticholinergic drugs are used to inhibit detrusor contractions and increase detrusor relaxation. This results in higher volumes and lower bladder pressures.

Anticholinergics remain the first-line therapy for detrusor overactivity. Common side effects of these drugs are dry mouth, constipation, blurred vision, increased heart rate and dental caries, with prolonged use. These medications are contraindicated for people with glaucoma.

Examples of these medications for overactive bladder are Oxybutynin (Ditropan or Oxytrol), Solifenacin (Vesicare), Mirabegron (Betmiga) and Tolterodine (Detrusitol).

Botulinum toxin for detrusor overactivity

Botulinum toxin A (BTX-A) inhibits muscle contractions by preventing the release of the neurotransmitter acetylcholine from axon endings at the neuromuscular junction. The advantage of botulinum toxin is that it is injected directly into the detrusor, minimising systemic side effects. This is injected under a general anaesthetic as a cystoscopy procedure, to reduce the risk of autonomic dysreflexia and potentially triggering spasticity and tone.

There are varying results with time frames of action and for most people it can be effective within a range of around 9-12 months. Consideration should be given if requiring Botulinum toxin A for musculoskeletal management, as there is usually a maximum dose that can be administrated systemically.

Alpha1A-adrenoceptor blocker for voiding

Alpha1A-adrenoceptor blockers can assist with voiding by acting on smooth muscle in the internal urethral sphincter. These medications are generally used for benign prostatic hyperplasia (BPH). They also have an antihypertensive effect.

Examples of these medications are Prazosin and Tamsulosin.