C H A P T E R 9
Antibiotics
105
Pharmacokinetics
Aztreonam is available for IV and IM use only and
reaches peak effect levels in 1 to 1.5 hours. Its half-life
is 1.5 to 2 hours. The drug is excreted unchanged in the
urine. It crosses the placenta and enters breast milk (see
contraindications and cautions).
Contraindications and cautions
Aztreonam is contraindicated with any known allergy
to aztreonam. Use with caution in people with a history
of acute allergic reaction to penicillins or cephalosporins
because of the possibility of cross-reactivity
; in those
with renal or hepatic dysfunction
that could interfere
with the clearance and excretion of the drug
; and in
pregnant and breastfeeding women
because of potential
adverse effects on the fetus or neonate.
Adverse effects
The adverse effects associated with the use of aztreonam
are relatively mild. Local GI effects include nausea, GI
upset, vomiting and diarrhoea. Hepatic enzyme eleva-
tions related to direct drug effects on the liver may also
occur. Other effects include inflammation, phlebitis and
discomfort at injection sites, as well as the potential for
allergic response, including anaphylaxis.
Care considerations for people receiving
macrolides, lincosamides or monobactams
Assessment: History and examination
■
■
Assess for
possible contraindications or
precautions
: known allergy to lincosamides,
macrolides and monobactams (obtain specific
information about the nature and occurrence of
allergic reactions); history of liver disease
that
could interfere with metabolism of the drug
; and
current pregnancy or breastfeeding status
because
of potential adverse effects on the fetus or infant.
■
■
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.
■
■
Examine the skin for any rash or lesions
to provide
a baseline for possible adverse effects.
■
■
Obtain specimens for culture and sensitivity testing
from the site of infection.
■
■
Monitor temperature
to detect infection.
■
■
Conduct assessment of orientation, affect and
reflexes
to establish a baseline for any CNS effects
of the drug.
■
■
Assess liver and renal function test values
to
determine the status of renal and liver functioning
and to determine any needed alteration in dosage.
■
■
Obtain baseline electrocardiogram
to rule out
conditions that could put the person at risk for
serious arrhythmias.
Implementation with rationale
■
■
Check culture and sensitivity reports
to ensure that
this is the drug of choice for this person.
■
■
Monitor hepatic and renal function test values
before therapy begins
to arrange to reduce dose
as needed.
■
■
Ensure that the person receives the full course
of the medication as prescribed
to eradicate the
infection and to help prevent the emergence of
resistant strains.
■
■
Ensure that the person swallows the tablet whole;
it should not be cut, crushed or chewed,
to ensure
therapeutic dose of the drug.
■
■
Monitor the site of infection and presenting signs
and symptoms (e.g. fever, lethargy, urinary tract
signs and symptoms) throughout the course of
drug therapy.
Failure of these signs and symptoms
to resolve may indicate the need to reculture the
site.
Arrange to continue drug therapy for at least
2 days after all signs and symptoms resolve,
to help
prevent the development of resistant strains.
■
■
Provide small, frequent meals as tolerated
to ensure
adequate nutrition with GI upset
; frequent mouth
care and ice chips or sugarless lollies to suck
to
provide relief of discomfort if dry mouth is a
problem
; and adequate fluids
to replace fluid lost
with diarrhoea.
■
■
Ensure ready access to bathroom facilities
to assist
people with problems associated with diarrhoea.
■
■
Institute safety measures
to protect person from
injury if CNS effects occur.
■
■
Arrange for appropriate treatment of
superinfections as needed
to decrease the severity
of infection and complications.
■
■
Instruct the person about the appropriate dosage
regimen and possible adverse effects
to enhance
knowledge about drug therapy and to promote
compliance.
For the monobactam agent aztreonam:
this drug can be given only IV or IM, so the person
will not be responsible for administering the drug.
■
■
For lincosamides, take additional precautions that
include careful monitoring of GI activity and fluid
balance and stopping the drug at the first sign of
severe or bloody diarrhoea.
■
■
Provide the following teaching:
–– Take safety precautions, including changing
position slowly and avoiding driving and
hazardous tasks, if CNS effects occur.
–– Try to drink a lot of fluids and to maintain
nutrition (very important) even though nausea,
vomiting and diarrhoea may occur.
