antibioticsbooks

Antibiotic
Pharmacokinetics
3
The term antibiotic pharmacokinetics refers to
how (and to what extent) antibiotics enter the body,
where they go once they are “inside,” and how they
get out. These three phases of pharmacokinetics
are usually described as absorption, distribution,
and metabolism/excretion (sometimes abbreviated
“ADME”). The pharmacokinetics of antibiotics are
key to the effectiveness of the drugs in clinical
practice; there is no benefit for a patient to receive
an antibiotic that is great at killing bugs if it never
gets to the site of the infection at a high enough
concentration to work. Figure 3–1 illustrates these
phases on a concentration–time curve, with the
concentration of the drug on the Y axis and the
time since drug administration on the X axis. It
also indicates the key pharmacokinetic parameters
of peak concentration, trough concentration, and
area under the concentration–time curve (“AUC”).
Absorption
Although the term “absorption” can be applied to
any route of administration (for example, absorption
from intramuscular injection or inhalation),
usually it is used to refer to the uptake of orally
administered drugs into the bloodstream. The percentage
of a nonintravenously administered drug