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P A R T 9
Drugs acting on the renal system
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Urinary tract anti-infectives destroy bacteria in the
urinary tract that could be causing infections.
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Urinary tract specific antibiotics prevent bacterial
reproduction and cause bacterial cell death.
■■
Some urinary tract anti-infectives kill urinary tract
bacteria by acidifying the urine, making the tract
a poor host for bacterial growth, or by killing the
bacteria outright.
■■
Hygiene measures, proper diet and extra hydration
are activities that help to decrease harmful bacteria
in the urinary tract, which promotes the effect of
urinary tract anti-infective agents.
URINARY TRACT ANTISPASMODICS
Urinary tract
antispasmodics
(Table 52.3) block the
spasms of urinary tract muscles caused by various con-
ditions. The antispasmodics that are available include
darifenacin (
Enablex
), oxybutynin (
Ditropan
), toltero-
dine (
Detrusitol
) and solifenacin (
Vesicare
)
.
Therapeutic actions and indications
Inflammation in the urinary tract, such as cystitis, pros-
tatitis, urethritis and urethrocystitis/urethrotrigonitis,
causes smooth muscle spasms along the urinary tract.
Irritation of the urinary tract leading to muscle spasm
also occurs in individuals with neurogenic bladder.
These spasms lead to the uncomfortable effects of
dysuria
(pain or discomfort with urination), urgency,
incontinence,
nocturia
(recurrent night time urination)
and suprapubic pain. The urinary tract antispasmodics
relieve these spasms by blocking parasympathetic
activity, thus suppressing overactivity, which leads
to relaxation of the detrusor and other urinary tract
muscles (see Figure 52.1). Because the parasympathetic
system uses acetylcholine to cause its effects, these drugs
are called anticholinergic drugs. See Table 52.3 for usual
indications of urinary tract antispasmodics.
Pharmacokinetics
All of these agents are administered orally with the
exception of oxybutynin, which is not only given orally
but is also available as a dermal patch. These drugs
are rapidly absorbed, have a slow onset of action and
have a duration of action of 6 to 12 hours. Oxybutynin,
when given by the transdermal system, has a duration of
action of 96 hours. The system has to be replaced every
4 days. These drugs are metabolised in the liver and
excreted in urine. They cross the placenta and are found
in breast milk.
KEY POINTS
■
■
Administer the drugs with food
to decrease GI
adverse effects if they occur.
■
■
Institute safety precautions if the person
experiences CNS effects
to prevent injury.
■
■
Advise people to continue the full course of the
drug ordered and not to stop taking it as soon as
the uncomfortable signs and symptoms pass
to
ensure eradication of the infection and prevent the
emergence of resistant strains of bacteria.
■
■
Encourage the person to drink lots of fluids (unless
contraindicated by other conditions)
to promote
flushing of the bladder and prevent urinary
stasis
,
and to avoid citrus juices and antacids,
which promote an alkaline urine and provide
opportunity for bacteria growth.
■
■
Provide or assist with perineal hygiene as indicated
to reduce the risk of re-infection or prevent
transmission of infection.
■
■
Explain to people with chronic UTIs about
additional activities that can facilitate an acidic
urine
to increase the effectiveness of urinary tract
anti-infectives.
■
■
Provide thorough teaching, including drug
name, dosage, intended effect and schedule for
administration; measures to prevent or alleviate
adverse effects; the need to avoid foods that
cause alkaline ash and produce an alkaline urine
(e.g. citrus juices, antacids); the need to take the
drug with food or meals to reduce GI effects; the
importance of increasing fluid intake, including
the use of cranberry juice; measures to prevent
the recurrence of UTIs; and the need for periodic
monitoring and laboratory testing such as
urinalysis, urine culture and sensitivity
to enhance
knowledge about drug therapy and to promote
compliance.
Evaluation
■
■
Monitor the person’s response to the drug
(resolution of UTI and relief of signs and
symptoms); repeat culture and sensitivity tests as
recommended for evaluation of the effectiveness of
all of these drugs.
■
■
Monitor for adverse effects (skin evaluation,
orientation and reflexes, GI effects).
■
■
Evaluate the effectiveness of the teaching plan
(person can name drug, dosage, adverse effects
to watch for, specific measures to avoid them and
measures to take to increase the effectiveness of the
drug).
■
■
Monitor the effectiveness of comfort and safety
measures and compliance with the therapeutic
regimen.
