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S3.M1.Pharm3
Drug Distribution
13
Pharmacology
Professional
05/19/2010

Additional Pharmacology Flashcards

 


 

Cards

Term
what is the Volume of Distribution equal to?
Definition
the (apparent) volume of fluid that would be required to contain the total amount of drug in the body at the same concentration as in plasma
Term
what does it mean when it says Vd is CONSTANT?
Definition
NOT dependent on administered dose
Term
how is the VOLUME OF DISTRIBUTION measurement used?
Definition
-To get a rough indication of the overall distribution of a drug in the body
-To plan dosage regimens
-To achieve a rough indication of the efficacy (or toxicity) of a given dose of a drug
Term
what do drugs mainly BIND to? two most common examples?
Definition
plasma protein -->ALBUMIN (if acidic) or to ALPHA1-ACID-GLYCOPROTEIN (if basic)
Term
is the extent to which drugs are bound to protein VARIABLE or CONSTANT?
Definition
VARIABLE
Term
PROTEINS that are bound are not available for what actions?
Definition
a) pharmacological actions
b) further distribution throughout the body
c) biotransformation
d) glomerular filtration
Term
how do Drugs reach the CNS?
Definition
a) CROSS THE CEREBRAL CAPILLARIES (i.e from plasma to the interstitial fluid)
b) CROSS THE CHOROID PLEXUS (i.e from plasma to the cerebrospinal fluid)
Term
The blood-brain barrier limits the transfer of drug into the central nervous system because:
Definition
-BRAIN CAPILLARY CELLS and CHOROID PLEXUS CELLS are bound together by an OCCLUDING ZONULAE
-Several drugs are actively transported out of the cerebrospinal fluid and back into the blood by a P-glycoprotein
Term
TRANSFER OF DRUGS ACROSS THE BLOOD-BRAIN BARRIER CARRIES WHAT REQUIREMENT?
Definition
must be LIPID soluble (lipid diffusion used)
Term
if a drug is not LIPID SOLUBLE, what method must be used to breach blood brain barrier?
Definition
must be administered by INTRATHECAL INJECTION directly into the CSF
Term
when is the BBB PERMEABILITY increased?
Definition
INFANTS and NEWBORNS, sickness (meningitis)
Term
is the PLACENTA typically permeable or impermeable to most drugs? is equilibration between mother and fetus generally fast or slow?
Definition
permeable, slow
Term
Factors affecting placental transfer of drugs include:
Definition
-drug size
-physicochemical properties of the drug (lipophilic +)
-degree of protein binding (drugs highly protein bound cross the placenta slowly)
-placental blood flow
-stage of placental development (later=better)
-placental drug metabolism
-activity of the of P-glycoprotein that is present in placental vessels
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