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chapter 9 Aminoglycosides 103
equally effective, more convenient, and possibly
safer dosing regimen. However, there are
many populations in which once-daily dosing
has had limited study, including the pregnant,
the critically ill, those with significant renal
dysfunction, and the morbidly obese. Use this
dosing method with caution, if at all, in these
populations. Aminoglycosides are pregnancy
category D and should be avoided if possible in
pregnant women anyway.
• Aminoglycoside serum levels can help guide
appropriate dosing and reduce the risk of toxicity,
but they must be drawn correctly to have
meaningful interpretations. For traditional
dosing methods, a peak level should be drawn
half an hour after the end of the infusion,
while trough levels should be drawn within
30 minutes of the next dose. For once-daily dosing
there are a number of potential monitoring
points, based on published nomograms.
• Aminoglycosides have relatively poor distribution
into many tissues, including the lungs.
They have minimal nervous system penetration.
This makes them less than optimal as
monotherapy for many severe infections. It
also means that a dose should be based on the
patient’s ideal or adjusted body weight, rather
than his or her total body weight. Given the
high prevalence of morbid obesity, serious
overdosing of patients can occur if the patient’s
total body weight is used.
• Some older drug references and textbooks
list streptomycin as a first-line treatment for
tuberculosis. While it was the first antituberculosis
drug available, it has been supplanted