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P A R T 2
Chemotherapeutic agents
The potential for nephrotoxicity and ototoxicity
with amikacin is very high, so the drug is used only as
long as absolutely necessary.
Adverse effects
The many serious adverse effects associated with amino-
glycosides limit their usefulness. The drugs come with
a black box warning, alerting healthcare professionals
to the serious risk of ototoxicity and nephrotoxicity.
Central nervous system (CNS) effects include ototoxic-
ity, possibly leading to irreversible deafness; vestibular
paralysis resulting from drug effects on the auditory
nerve; confusion; depression; disorientation; and
numbness, tingling and weakness related to drug effects
on other nerves.
Renal toxicity, which may progress to renal failure,
is caused by direct drug toxicity in the glomerulus,
meaning that the drug molecules cause damage (e.g.
obstruction) directly to the kidney. Bone marrow depres-
sion may result from direct drug effects on the rapidly
dividing cells in the bone marrow, leading, for example,
to immune suppression and resultant superinfections.
GI effects include nausea, vomiting, diarrhoea,
weight loss, stomatitis and hepatic toxicity. These effects
are a result of direct GI irritation, loss of bacteria of the
normal flora with resultant superinfections, and toxic
effects in the mucous membranes and liver as the drug
is metabolised.
Cardiac effects can include palpitations, hypotension
and hypertension. Hypersensitivity reactions include
purpura, rash, urticaria and exfoliative dermatitis.
Clinically important drug–drug interactions
Most aminoglycosides have a synergistic bactericidal
effect when given with penicillins, cephalosporins or
ticarcillin. In certain conditions, this synergism is used
therapeutically to increase the effectiveness of treat-
ment. Avoid combining aminoglycosides with potent
diuretics; this increases the incidence of ototoxicity,
nephrotoxicity and neurotoxicity. If these antibiotics are
given with anaesthetics, non-depolarising neuromuscu-
lar blockers, succinylcholine or citrate anticoagulated
blood, increased neuromuscular blockade with paralysis
is possible. If a person who has been receiving an amino-
glycoside requires surgery, indicate prominently on the
person’s chart the fact that the aminoglycoside has been
given. Provide extended monitoring and support after
surgery.
Prototype summary: Gentamicin
Indications:
Treatment of serious infections caused
by susceptible bacteria.
Actions:
Inhibits protein synthesis in susceptible
strains of gram-negative bacteria, disrupting
functional integrity of the cell membrane and
causing cell death.
Pharmacokinetics:
Route
Onset
Peak
IM, IV
Rapid
30–90 minutes
T
1/2
:
2 to 3 hours; metabolised in the liver and
excreted in the urine.
Adverse effects:
Sinusitis, dizziness, rash, fever, risk
of nephrotoxicity.
Care considerations for
people receiving aminoglycosides
Assessment: History and examination
■
■
Assess for
possible contraindications or cautions:
known allergy to any aminoglycoside (obtain
specific information about the nature and
occurrence of allergic reactions); history of renal
or hepatic disease; pre-existing hearing loss;
active infection with herpes, vaccinia, varicella or
fungal or mycobacterial organisms; myasthenia
gravis; parkinsonism; infant botulism; and current
pregnancy or breastfeeding status.
■
■
Perform a physical assessment
to establish baseline
data for assessing the effectiveness of the drug and
the occurrence of any adverse effects associated
with drug therapy.
■
■
Perform culture and sensitivity tests at the site of
infection.
■
■
Conduct orientation and reflex assessment, as well
as auditory testing,
to evaluate any CNS effects of
the drug
.
■
■
Assess vital signs: respiratory rate and adventitious
sounds
to monitor for signs of infection or
hypersensitivity reactions
;
temperature
to assess
for signs and symptoms of infection
;
blood
pressure
to monitor for cardiovascular effects of
the drug.
■
■
Perform renal and hepatic function tests
to
determine baseline function of these organs and,
possibly, the need to adjust dose.
Implementation with rationale
■
■
Check culture and sensitivity reports
to ensure that
this is the drug of choice for this person.
■
■
Ensure that the person receives a full course of
aminoglycoside as prescribed, divided around
the clock,
to increase effectiveness and decrease
the risk for development of resistant strains of
bacteria.
