Drug Absorption Flashcards
correct pharmacological effect - effect of drug on the body
Pharmacodynamic
drug to site of action
what your body does to the drug?
how removed?
ADME
Pharmacokinetic
drug into patient
Pharmaceutical
The time to peak concentration
(Tmax)
The more rapid the rate of absorption, the earlier the drug concentration peak.
The peak concentration
(Cmax)
Increasing dose does not reduce the time at which peak concentration is reached but does increase the peak concentration
Total exposure to drug; amount of drug reaching systemic circulation
AUC
The area under the drug concentration-time curve represents the amount of drug which reaches the systemic circulation.
measure of the range at which a drug is safe and active
therapeutic index
Index lower - oral - plasma conc low - compared to other route of administration
drug is active over a range of concentrations
therapeutic range
A drug given _________ has 100% bioavailability.
intravenously
Factors affecting bioavailability (oral) - list 5
Formulation Ability of drug to pass physiological barriers/transport across memb- Particle size, Lipid solubility, pH and ionisation (unionised - cross lipid but do not dissolve in H20 / ionised cannot cross memb GI effects First pass metabolism Slow release preparations
Does ionised drug cross the membrane?
No.
Most drugs are weak acids or bases; the degree of ionisation depends on the pH of the environment.
Most drugs do not completely ionise in water.
The ability of a drug to diffuse across a lipid barrier
a lipid-water partition coefficient.
This is the ratio of the amount of drug which dissolves in the lipid and water phase when they are in contact.
To pass across a lipid layer a drug must be in solution and ________ soluble.
lipid
A drug that is not lipid soluble may not be absorbed at all, for example gentamicin.
To undergo active transport drugs must resemble ______
naturally occurring compounds.
____________occurs through inter-cellular pores and is the major mechanism through which drugs cross the capillary walls.
Filtration
normal method for water soluble molecules with a molecular weight of 100 or less.
