Kinetics 6.5 - 9.5 Flashcards
Time required for the amount of drug to fall by 50%
HALF-LIFE (t½)
Unit for hal-life
Indicates the time required to 50% of
steady state – or to decay 50% from steady
state conditions
Unit: Time (hrs)
HALF-LIFE
Derived parameter, determined by ____ and ___
Vd and CL
Every time na dumadaan ung blood carrying the
blood in the organs of elimination like the liver or
the kidneys, the drug is eliminated and the half-life
is shortened or the drug’s presence in the plasma.
N/A
Determines the rate at which blood concentration
rises during a constant infusion and falls after
administration is stopped
HALF-LIFE (t½)
What do you call this?
Intravenous administration only reaches
100 percent bioavailability
■ Unity or 100%
BIOAVAILABILITY
T/F: Administration by other routes: Reduced by incomplete absorption
TRUE
Drugs are more absorbed in the _________.
because it has a larger surface area.
SMall intestines
The ______ determines the rate at which blood
concentration rises during a constant infusion and falls after administration is stopped
half-life
T/F: half
life is increased before
eliminating/clearing.
tRUE
Whenever drug doses are repeated, the drug will accumulate in the body until dosing stops.
This is because it takes an infinite time (in
theory) to eliminate all of a given dose
DRUG ACCUMULATION
this means that if the
dosing interval is shorter than four
half-lives, accumulation will be detectable.
Accumulation is (directly/inversely) proportional to the
fraction of the dose lost in each dosing interval.
inversely
Average total amount of drug in the body does not
change over multiple dosing cycles
Steady state
Rate of drug input equals the rate of elimination
Steady state
PEAK AND TROUGH CONCENTRATIONS
determines the desired trough levels of a drug given intermittently
- MEC
- MTC
Through concentration ay kinukuha just before the
next dose. Bago ka uminom or orally or bago iinject
ng Intravenous
MEC (Minimum Effective Conc.)
PEAK AND TROUGH CONCENTRATIONS
determines the permissible peak plasma concentration
- MEC
- MTC
The peak will be less than or below the minimum
toxic concentration. Peak concentration ay kinukuha when it is already fully absorbed and distributed
MTC (Minimum Toxic Conc. )
Depends on the extent of absorption
Bioavailability
Bioavailability
T/F: If it undergoes the first pass effect by the liver, the speed or rate of their absorption as well as the site of their administration
TRUE
is defined as the fraction of
unchanged drug reaching the systemic circulation following administration by any route
Bioavailability
T/F:The area under the blood concentration-time curve
(AUC) is proportional to the dose and the extent of
bioavailability for a drug if its elimination is
first-order
True
is proportional to the dose and the extent of
bioavailability for a drug if its elimination is
first-order
The area under the blood concentration-time curve
(AUC)
T/F: For an intravenous dose, bioavailability is assumed to be equal to unity
True
For a drug administered orally,
bioavailability may be less than 100% for two main reasons:
- incomplete extent of absorption across the gut wall
- first-pass elimination by the liver
ROUTES OF ADMINISTRATION, BIOAVAILABILITY
Routes: ______
Bioavailability: 100 by definition
Characteristics:Most rapid onset
Intravenous (IV)
Routes: ______
Bioavailability: 75 to ≤100
Characteristics: Large volumes
often feasible; may be painful
Intramuscular
(IM)
Routes: ______
Bioavailability: 75 to ≤100
Characteristics:Smaller volumes
than IM; may be painful
Subcutaneous
(SC)
Routes: ______
Bioavailability: 5 to ≤100
Characteristics: Most convenient;
first-pass effect 5 to ≤100may be important
Oral (PO)
Routes: ______
Bioavailability: 30 to ≤100
Characteristics: Less first-pass effect than oral
Rectal (PR)
Routes: ______
Bioavailability: 5 to ≤100
Characteristics: Often vary rapid onset
Inhalation
Routes: ______
Bioavailability: 80 to ≤100
Characteristics: Usually very slow
absorption; used for lack of
first-pass effect; prolonged duration of action
Transdermal
