Module 2 (L6-11) Flashcards
what is the therapeutic range?
above the minimal effective concentration (MEC) and bellow the minimal toxic concentration (MTC)
the space between adverse effects and desired response
what is topical administration?
local, commonly used on the skin or mucosal membranes (gel, cream or inhalation)
what is the advantage of topical administration
if you want a drug in a particular site but don’t want the drug in high conc in the body, it enhances the selectivity of the drug and has minimal exposure of the drug at any other sites
what is eternal administration
via the GI tract, oral drigs are common, safe, self administrable so are the ideal drug type but may have slow on set and not possible if the patient is unconscious or vomiting, it partly avoids first pass metabolism
what is parenteral administration
avoids the Gi tract so there are no absorption problems. IV bolus which is an all or one intravenous injection and is quick and reliable can be dangerous and painful. IV fusion is the constant infusion of a drug, it is a slow process but reliable, controllable and used for large volumes. IM (intramuscular) is relatively fast and may be painful
what factors alter absorption rates?
- drug needs to be able to pass a lipid membrane
- oral drugs need to be absorbed in the intestine
- the rate at which material passes through the GI tract determines the rate that it si absorbed
- level of GI motility can alter absorption rate
- foods can alter absorption rates because some drugs form complexes with cations which are then poorly absorbed
what is the bioavailability
the fraction of an orally administered dose reaching the systemic circulation is known
what is drug distribution dependent on?
the blood flow from tissue to organs, partitioning into non-aqueous phases and binding to plasma proteins and tissue components, only free (unbound) drugs can move between compartments
Describe volume of distribution
a measure of a drugs tendency to distribute away from the plasma and it is determined by measuring plasma conc after IV bolus
if the drug was not lipid-soluble it would still be in the blood
the larger the number the greater the tendency for the drug to diffuse into the blood
what does a large volume of distribution mean
it indicates the drug leaves the plasma, it will be tightly bound to tissues with a high lipid solubility so the drug appears to be dissolved in an very large volume
what does a small volume of distribution mean
indicates that the drug stays in the plasma tightly plasma protein bound, very polar (high water solubility) and the Vd can be close to the blood volume
What does the CSS mean
when the rate of drug going into the body is equal to the rate of the drug going out of the body
what is the loading dose and how do you calculate it
it is the desired CSS allowing for incomplete bioavailability
loading dose = target CSS x Vd
where does absorption and elimination take place?
in the gut wall and liver
what does the liver do
it detoxifies and carries out most of the drug metabolism
