Study Set Content:
Even
though both dosing schemes produce the same
average steady-state concentration, the intermittent
dosing scheme produces much higher peak
concentrations, which saturate an uptake
mechanism into the cortex; thus, total
aminoglycoside accumulation is
less
The difference
in toxicity is a predictable consequence of the
different patterns of concentration and the saturable
uptake mechanism.
A (blank) is based on the
assumption that there is a target concentration that
will produce the desired therapeutic effect.
rational dosage regimen
By
considering the pharmacokinetic factor determine
the dose-concentration relationship, it is possible to
(blank) the dose regimen to achieve the target
concentration.
individualize
should usually be
chosen from the lower end of this range
The initial target concentration
In some cases, the target concentration will also
depend on the specific
therapeutic objective.
the control of atrial fibrillation by
digoxin
eg, the control of atrial fibrillation by digoxin often
requires a target concentration of
2 ng/mL,
while
heart failure is usually adequately managed with a
target concentration of
1 ng/mL,
In most clinical situations, drugs are administered in
such a way as to maintain a(blank) of drug in
the body.
steady state
ie, just enough drug is given in each dose to replace
the drug eliminated since the
preceding dose
Thus, calculation of the appropriate maintenance
dose is a
primary goal
If intermittent doses are given, the maintenance
dose is calculated from:
Maintenance dose = Dosing rate X Dosing interval/F
When the time to reach steady state is appreciable,
as it is for drugs with long half-lives, it may be
desirable to administer a loading dose that promptly
(blank) of drug in plasma to the
target concentration.
raises the concentration
the loading dose
V X TC
For most drugs, the loading dose can be given as a
single dose by the chosen
route of administration.
THREE MAJOR PHARMACOKINETIC VARIABLES:
1. Absorption
2. Clearance
3. Volume of distribution
TWO PHARMACODYNAMIC VARIABLES:
1. Maximum effect attainable in the target tissue
2. Sensitivity of the tissue to the drug
The amount of drug that enters the body depends on
the patient’s adherence to the prescribed regimen
and on the rate and extent of transfer from the site
of administration to the blood.
INPUT
(blank) relative to the
prescribed dosage—both aspects of failure of
adherence—can frequently be detected by
concentration measurements when gross deviations
from expected values are obtained.
Overdosage and underdosage
