Ch 4 Pharmacokinetics / Dynamics Flashcards
The study of drug movement through the body
Pharmacokinetics
Name the four Basic processes of pharmacokinetics
Absorption
distribution
metabolism
excretion
The drugs movement from the site of administration into the blood
Absorption
The movement of the drug from the blood to the interstitial space of tissues and from there into the cells
Distribution
The enzymatically mediated alteration of drug structure. This is also known as biotransformation
Metabolism
The movement of drugs and their metabolites out of the body
Excretion
True or false: the combination of metabolism and excretion is called elimination
True
The goal of applying knowledge of pharmacokinetics to drug therapy is to maximize beneficial effects and minimize harm
True
True or false: distribution is the only phase of pharmacokinetics that involves drug movement across membranes
False: To move through the body in all four phases of pharmacokinetics drugs must cross membranes
Name the three ways drugs can cross cell membranes
Channels or pores
passage with the aid of a transport system
direct penetration of the membrane (most common)
True or false: membranes are composed primarily of lipids therefore to directly penetrate a membrane - a drug must be lipid soluble.
True
True or False: potassium and sodium are too large to cross membranes through channels or pores
False: K+ and Na+ are examples of the smallest of compounds that can pass through these channels if the channel is the right one.
Name two kinds of molecules that are not lipid soluble and cannot penetrate membranes
Polar molecules
ions
True or false: water is an example of an ion with a positive charge
False: water is an example of a polar molecule that has no net charge
True or False: Ions are an example of molecules that have a net positive charge
False: ions are molecules that have a net electrical charge that can be either positive or negative
___________ Is the process whereby a drug accumulates on the side of a membrane where the pH most favors it’s ionization
Ion trapping
Acidic drugs accumulate on the ___________ side
Alkaline
Basic drugs accumulate on the __________ side
Acidic
What five factors affect drug absorption
Rate of dissolution
surface area
blood flow
lipid solubility
PH partitioning
True or false: the rate of absorption determines how soon effects will begin where is the amount of absorption helps determine how intense effects will be
True
True or false: drug preparations are considered chemically equivalent if the drug they contain is absorbed at the same rate in to the same extent
False: Drug preparations are considered chemically equivalent if they contain the same amount of the identical chemical compound / drug
Preparations are considered equal in bio availability if the drug they contain is absorbed at the same rate in to the same extent
What three processes affect drug distribution ?
Blood flow to the tissues,
the ability of a drug to exit the vascular system,
the ability of a drug to enter cells
Why must abscesses usually be surgically drained for drug therapy to be effective?
Abscesses have no internal blood vessels so they have no blood supply therefore antibiotics cannot reach the bacteria within
___________ Is a transporter known as a multi drug transporter protein that transports a wide variety of drugs out of cells
P - glycoproteins (PGP)
Most drug metabolism takes place in the _________
Liver
What is another name for the hepatic microsomal enzyme system that takes place in the liver?
P450 or cytochrome P450 which is made of 12 closely related enzyme families
Name the three P450 families that metabolize drugs
CYP1
CYP2
CYP3
The other 9 P450 enzyme families metabolize __________ compounds like ______ &________.
Endogenous
Steroids and fatty acids
What is the most important consequence of drug metabolism and why
Promotion of renal drug excretion is the most important consequence because the kidneys are the major organ of drug excretion. They cannot excrete drugs that are highly lipid soluble. If drugs can be converted into more hydrophilic forms metabolic conversion can accelerate renal excretion of many agents
Name six consequences of drug metabolism of therapeutic significance
Accelerated renal excretion of drugs,
drug and activation,
increased therapeutic action,
activation of pro drugs,
increased toxicity,
decreased toxicity
Metabolism converting codeine and some morphine is an example of what
Increased therapeutic action
This is a compound that is pharmacologically an active as administered and undergoes conversion to it’s active form through metabolism
Prodrug
This refers to the rapid hepatic an activation of certain oral drugs
First pass effect
This is the time required for the amount of drug in the body to decrease by 50% and determines dosing interval
Drug half life
The study of the bio chemical and physiologic effects of drugs on the body and the molecular mechanisms by which those effects are produced
Pharmacodynamics
The largest defect that he drug can produce
Maximal efficacy
The amount of drug we must give to elicit an effect it’s indicated by the relative position of the dose response curve
Potency
This is any functional macromolecule any cell to which a drug binds to produce it’s effects
Receptor
This refers to the strength of the attraction between a drug and it’s receptor
Affinity
Drugs with higher Affinity are very potent
The ability of a drug to activate a receptor up on binding
Intrinsic activity
Drugs with high intrinsic activity have high maximal efficacy
True or false: agonist are molecules that deactivate receptors
FALSE
Agonists - ACTIVATE
True or false: antagonists produce their effects by preventing receptor activation by endogenous regulatory molecules and drugs
TRUE
The average effective dose - this is also defined as the dose required to produce a defined therapeutic response in 50% of the population
ED50
This is a measure of a drugs safety it is defined as the ratio of a drugs lethal dose (LD50) to its effective dose (ED50). The larger this is the safer the drug is
Therapeutic index
When another substance alters a drug efficacy effects or safety
Drug interaction
True or false: albuterol and propanolol should not be taken together
True : Propanolol reduce his albuterol therapeutic effects
Which isoenzyme does grapefruit juice effect by inhibiting metabolism metabolism
CYP3A4
Name some examples of food on drug
MAO inhibitor combined with foods rich in tyramine like aged cheeses yeast extract and she Chianti wine. This combination causes life-threatening elevation and blood pressure
Theophylline combined with caffeine can cause excessive CNS excitation
Potassium sparing diuretics like spironolactone plus salt substitute can result in dangerously high potassium levels
Aluminum containing antacids plus citrus beverages can result in excessive absorption of aluminum
How does vitamin K reduce the effects of warfarin?
Warfare and inhibits vitamin K dependent clotting factors so in vitamin K is more abundant warfarin and is less able to inhibit the clotting factors and therapeutic effects decline
