chap 4 Flashcards
___consists of 4 basic processes…absorption, distribution, metabolism and excretion
pharmacokinetics
_______drugs ionize in basic alkaline media whereas ______drugs ionize in acidic media
acidic
basic
____is defined as the movement of a drug from its site of administration into the blood
absorption
_____is enhanced by rapid drug dissolution, high lipid solubility of the drug, a large surface area of absorption and high blood flow at the site of administration
absorption
____ administration has several advantages rapid onset, precise control over the amount of drug entering the blood, suitability for use with large volumes of fluid, and suitability of irritant drugs
Intravenous
to move around the body , drugs must cross____ either by passing thru pores, undergoing transport, penetrating the membrane directly
membranes
____ processes determine the concentration of a drug at its sites of action, and thereby determine the intensity and time course of responses.
pharmacokinetic
____administration has several disadvantages, high cost, difficulty, inconvenience, danger because of reversibility, potential for fluid overload, infection and embolism
Intravenous
___administration has 2 advantages suitability for insoluble drugs and for depot preparations
Intramuscular
____administration has 2 disadvantages inconvenience and discomfort.
intramuscular
__administration has the same advantages and disadvantages as intramuscular administration
subcutaneous
___administration has the advantages of ease, convenience, economy and safety
Oral
____ administration disadvantages are high variability, possible inactivation by stomach acid, digestive enzymes, liver enzymes( because ____ must pass thru liver before reaching general circulation
oral
oral
____ is defined as the movement of drugs thru out the body
distribution
In most____drugs can easily leave the vasculature thru spaces between cells that compose the capillary wall
tissues
The term _____refers to the presence of tight junctions between the cells that compose capiilary walls in the
CNS. so drugs must pass thru the cells of the capillary wall, rather than between them, to reach the CNS
blood brain barrier BBB
the membranes to the ____ do not constitute an absolute barrier to the passage of drugs.
placenta
Many drugs bind reversibly to___ . while bound to ____ drug molecules cannot leave the vascular system.
plasma albumin
albumin
____is defined as the enzymatic alteration of drug structure
drug metabolism (biotransformation)
Most drug metabolism takes place in the ___ and is catlyzed by the cytochrome P450 system of enzymes
liver
The most importance consequence of ___ ___ is promotion of renal drug excretion by converting lipid soluable drugs into more hydrophillic forms
drug metabolism
Drugs that are metabolized by P450 enzymes are called ___
substrates
The rate at which ___ are metabolized is affected by drugs that act as P450 inducers or inhibitors
substrates
Drugs that act on the liver to increase rates of metabolism are ____
inducers
This process of stimulating enzyme synthesis in known as ____.As the rate of drug metabolism increases, plasma drub levels____.
induction
fall
Drugs that act on the liver to decrease rates of drug metabolism are called_____. the process in known as ___
inhibitors
inhibition
This creates a therapeutic consequences because slower metabolism can cause a _____ in active drug accumulation. this can lead to an ____ in adverse effects and toxicity.
increase
the term _____ refers to the rapid inactivation of some oral drugs as they pass thru the liver after being absorbed
first-pass effect
Most drugs are excreted by the ____
kidneys
____ excretion has 3 steps glomerular filtration, passive tubular reabsorption, and active tubular secretion
renal
Drugs that are highly ___soluble undergo extensive passive reabsorption back into the blood and therefore cannot be excreted by the kidneys until they are converted to more polar forms by the liver.
lipid
For most drugs there is a direct correlation between the level of the drug in the ____ and the intensity of therapeutic and toxic effects.
plasma
___ _____ is a repeating cycle in which a drug undergoes glucurnidation in the liver , transport to the duodenum by bile, hydrolytic release of free drug by intestinal enzymes , followed by transport in the portal blood back to the liver, where the cycle can begin again
enterohepatic recirculation
the ___ is defined as the plasma level below which therapeutic effects will not occur.
MEC minimum effective concentration
the ___ ____ of a drug lies between the MEC and the toxic concentration.
therapeutic range
drugs with a ___ ___ ____ are relatively easy to use safely. drugs with a ___ ___ ___ are difficult to use safely
wide therapeutic range
narrow therapeutic range
The __ ___ of a drug is defined as the time required for the amount of drug in the body to decline by 50%.
half life
Drugs that have a short half life must be administered ____ frequently than drugs that have a long half life
more
When drugs are administered repeatedly, their levels will gradually rise and then reach a steady ____
plateau
The time required to reach plateau is ___ of dosage size although the height of the plateau will be higher with larger doses
independent
For a drug with a ____ half life it may be necessary to use a loading dose to achieve plateau quickly.
long
when drug administration is discontinued most 94% of the drug in the body will be eliminated over ___ __ __
4 half lives
