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© The Canadian Journal of Urology™; 18(Supplement 1); April 2011
TABLE 7.
Antimuscarinic medications for overactive bladder
Name (Brand)
Dose
Notes
Darifenacin
7.5 mg-15 mg daily
Hepatic dosing; no change in
(Enablex)
dosing with renal insufficiency
Fesoterodine
4 mg-8 mg daily
Maximum 4 mg daily in renal insufficiency
(Toviaz [US, not Canada])
or if taking other CYP3A4 inhibitors
Hyosycamine
0.125 mg every 6 hours
Less specific than newer medications,
(Levsin [US, not Canada])
greater incidence of side effects
Oxybutynin IR
5 mg BID or QID
Antispasmodic and local anesthetic properties
(Ditropan)
Oxybutynin ER
5 mg-30 mg daily
Not studied in renal or hepatic impairment
(Ditropan XL/Uromax
(extended release)
[Canada only]
Oxybutynin gel
1 gm to skin daily
Apply to abdomen; upper arms; thighs or
(Gelnique 10%
shoulders; sites should be rotated; do not apply
[US, not Canada])
to same site for consecutive days
Oxybutynin transdermal
Apply twice weekly –
Not studied in renal or hepatic impairment
Oxytrol [patch]
1 patch, delivers 3.9 mg/day
Solifenacin
5 mg-10 mg daily
Reduce dose in renal or hepatic dysfunction
(Vesicare)
Tolterodine
1 mg-2 mg BID
Special dosing for hepatic dysfunction
(Detrol, Detrol LA)
(IR formulation)
2 mg-4 mg daily
(ER formulation)
Trospium (Trosec [Canada], 20 mg BID
Reduce dose for renal insufficiency; dose not
Sanctura [US},
(IR formulation)
cross blood brain barrier (fewer cognitive side
Sanctura XR [US])
60 mg daily
effects); take ER formulation 1 hour before meals
(ER formulation)
OAB commonly include neurologic conditions (e.g.
stroke or multiple sclerosis), detrusor smooth muscle
remodeling secondary to BPE, as well as several other
idiopathic conditions.
44
Patients suffering from OAB
can experience a significant decrease in quality of life
and suffer fromamultitude of resulting conditions (e.g.
urinary tract infections, falls, skin irritation, etc).
50-53
Pharmacology
Antimuscarinic medications are the mainstay of
medical therapy for treatment of OAB, Table 7. They
act by inhibiting M2 and M3 receptors located on
detrusor smooth muscle cells within the bladder.
54
Antimuscarinics reduce urgency and increase bladder
capacity but lack total selectivity for the bladder
leading to a multitude of side effects limiting their
efficacy. Dry mouth and constipation are the most
common with gastroesophageal reflux, blurred
vision, cognitive impairment, and sedation also
reported. Octogenarians or those with baseline
dementia who take anticholinergics must be warned
of possible worsening cognitive impairment. This
class of medications is contraindicated in any patient
with narrow angle glaucoma or a history of urinary
retention.
Among the first antimuscarinics was hyoscyamine
[Levsin (US only)], a naturally occurring compound
found in certain plants of the
Solanaceae
family.
However, it is a non-selective antimuscarinic that has
several systemic side effects limiting its use in light
of the advent of newer medications. Oxybutynin
[Ditropan, Ditropan XL, Oxytrol, Uromax] and
tolterodine [Detrol, Detrol LA] have been historically
the most widely used antimuscarinics for treatment
of OAB. They are available in short acting and
extended release forms, transdermal patches,
and gel applications [Gelnique (US only)].
55
The
extended release and transdermal formulations of
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LIU ET AL.