We live in a world in which many drugs are prescribed
for multiple medical problems. It stands to reason
that some of them may have adverse health effects
on other body areas that they were not meant to affect.
This is certainly true of drug effects on the urinary
tract. Many medications actually worsen or cause urinary
leakage. There are several different mechanisms by
which drugs can affect the urinary continence physiologic
systems. These are discussed in a recent article,
Steele AC, Kohli N, Mallipeddi P, Karram M: Pharmacologic
causes of female incontinence. Int Urogynecol J. 1999;
10:106:110. It answers some of the questions of how
medications we take for other medical problems can
actually cause or aggravate urine loss.
How can drugs cause urinary incontinence?
Continence and voiding are complex physiologic mechanisms
and as such, different components of voiding and holding
urine can be affected by pharmacologic actions of
many drugs. The urethra, which is the tube from the
bladder to the outside, needs to be closed constantly
to prevent leakage. Medicines such as alpha blockers
that relax the urethral muscle, will cause or worsen
incontinence.
The detrusor bladder muscle that contracts to empty
all urine can affect incontinence in two ways. If
it contracts too frequently and too strongly, the
bladder pressure will overcome the closed urethra
muscle and cause urine to leak out. Thus medications
that stimulate the detrusor muscle or cause spasms
of that muscle will cause incontinence. A second detrusor
muscle effect associated with incontinence is almost
the opposite of causing contraction. If a drug blocks
the bladder detrusor muscle from contracting, the
bladder will continue to fill up and become over-distended.
It does not rupture however. Ultimately a bladder
gets too full and a non-voluntary reflex mechanism
takes over and strongly contracts to empty the bladder
and prevent over distension and rupture. This contraction
is so strong that it overcomes the muscle tone holding
the urethra shut and a large volume of urine is voided.
Excess urine production can also be associated with
urinary leakage. It does not cause incontinence, but
when there is already a weakened continence mechanism
by muscle relaxation due to other medications or due
to anatomical weaknesses, then the rapid production
of urine either by diuretic drugs (water pills) or
even by just drinking excessive amounts of water,
will overwhelm the impaired continence forces and
result in urine leakage.
Do medications prescribed for hypertension cause
incontinence?
Yes, antihypertensive medicines are one of the most
frequent causes of urinary leakage. Medicines such
as prazosin (Minipress®), terazosin (Hytrin®),
doxazosin (Cardura®), alpha-methyldopa (Aldomet®)
and reserpine (Diupres®,Hydropres®) will cause
relaxation of the urethral muscle. Antiseizure medicines
such as thioridazine, chloropromazine (Thorazine®),
haloperidol (Haldol®), and clozapine (Clozaril®)
also are known to have an alpha blocker effect and
are especially associated with night time urinary
loss. Anti-anxiety and muscle relaxant drugs of the
benzodiazipine class such as Valium®, Xanex®
and Klonopin® also weaken the external urethral
sphincter muscle so if there is already some compromise
of the rest of the urethral muscle, leakage takes
place.
Diuretic pills (water pills) are commonly prescribed
for high blood pressure and medications like furosemide
(Lasix®) or hydrochlorothiazide (Diuril®)
can deliver a bolus of urine to the bladder that will
overcome any weakened muscle physiology.
I sometimes feel I cannot pass my urine and yet other
times it leaks uncontrollably. Can my medications
cause this?
This is often a sign of a drug effect that blocks
contraction of the bladder muscle until the bladder
fills so full that an uncontrollable detrusor contraction
suddenly causes overflow incontinence. Any medication
that slows down bowel motility such as those given
for irritable bowel syndrome or drugs that produce
constipation may cause this. Anti-Parkinsonism drugs
and some antihypertensive drugs also block the bladder
detrusor .
Medications causing incomplete bladder emptying include:
hyoscyamine (Cystospaz®, Urised®, Donnatal®,
Levbid®. Levsin®)
oxybutinin (Ditropan®)
benztropine (Cogentin®)
trihexyphenidyl (Artane®)
pindolol (Pindolol®)
disopyramide (Norpace®)
What side effects from medications should I watch
out for if I already have urinary leakage?
Any drugs that produce constipation may aggravate
urinary incontinence. Iron and narcotic pain medicine
therapy are often guilty of causing these effects.
The straining (increased intraabdominal pressure)
caused by constipation puts excessive pressure on
the bladder emptying muscle. That, in turn, overcomes
the muscle tone of the contracting urethra.
Any medication that has a side effect of producing
a chronic cough will lead to increased urinary incontinence.
Antihypertensive ACE inhibitor medications such as
Vaseretic®, Vasotec®Lotensin® Monopril®,
Zestril® can all produce a chronic cough. Stopping
or changing these medications can significantly improve
bladder control.
|
