Doxycycline
Pharmacotherapeutics
Pharmacodynamics
Pharmacokinetics
Water-soluble tetracycline
antibiotic that kills and prevents the
growth of a wide range of grampositive and gram-negative bacteria
It binds to the 30S prokaryotic
ribosomal preventing the
association of the charged
aminoacyl-tRNA (aa-tRNA) with
the ribosomal A site to stall the
elongation phase, yielding an
unproductive cycle of protein
synthesis
Absorption: Doxycycline is readily
absorbed and are bound to plasma
proteins by varying degrees.
Doxycycline is almost completely
absorbed after oral administration
as it is highly lipid soluble. Peak
serum levels of approximately 2.6
mcg/ml are reached at 2 hours
following a 200 mg tablet oral
dose.
Distribution: Doxycycline diffuses
readily into most body tissues,
fluid, and cavities with a volume of
distribution of 0.7 L/kg
Metabolism: Doxycycline is
metabolized in the liver and
gastrointestinal tract. It is
concentrated in bile. It has been
found that enzyme inducers have
been found to decrease the halflife of doxycycline 16
Elimination: Mainly the urine and
feces as active and unchanged
drug. It is estimated that 40% and
60% of an administered dose can
be accounted for in the urine by 92
hours, and roughly 30% excreted
in feces.