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Pharmacokinetics & Pharmacodynamics - AMJ

Terms in this set (52)

Absorption
The process by which a drug moves from its site of administration, such as the muscle, digestive tract, rectum, lungs, or skin, and into the circulatory system.
How the drug is administered affects its absorption.
Adrenergic
1. Relating to drugs that mimic the action of the sympathetic NS.
2. They act on specific beta-2 (pulmonary) adrenergic receptors.
3. A-receptors induce BRONCHODILATION by blocking the effects of natural epinephrine.
Think albuterol
Adverse effects
Any additional unwanted effects of a drug.
Affinity
The strength of the binding between a drug and its receptor.
Agonist
Stimulates/promotes a drug's effect or activity.
Antagonist
Blocks/prevents a drug's effect or activity.
Blood-brain barrier (BBB)
Barrier that restricts transfer of lipid-soluble drugs into the brain, whereas elsewhere in the body capillary walls are easily permeated by lipid-soluble drugs.
Drugs tend to be poor at penetrating into the central nervous system because they are actively pumped out, are highly charged molecules, or have a high molecular weight and cannot pass through the lipid membranes.
Brand name or Trade name
Generic name is hard to use, so make a name that will stand out for marketing reasons.
Register with US Trademark office.
example: Tylenol acetaminophen, Prozac fluoxetine .
Chemical name
The precise description of a drug's chemical structure.
Competitive antagonist
Reversible antagonist.
A drug that competes with an agonist for binding to a receptor.
Cytochrome P450 system
CYP450.
A group of liver enzymes responsible for most oxidative reactions of drugs.
Hormone synthesis and breakdown, synthesis of cholesterol, Vit D synthesis.
Dose response curve
A drawn graph illustration of the amount of drug given and its response.
Distribution
The pattern by which drugs are distributed throughout various tissues after the drug has entered the circulatory system and is on its way to its site of action.
Because of differences in pH, lipid content, cell membrane functions, and other individual tissue factors, most drugs are not distributed equally in all parts of the body.
Drug
Any substance that is used for the diagnosis, cure, treatment, or prevention of a disease or condition. Prescribed or not.
Drug receptors
Any portion of a tissue or cell to which a drug can bind and initiate its macromolecular effect(s).
Receptors can cause an effect when activated or blocked because, in essence, they are sensing elements that help to coordinate the functions of all the different cells in the body.
How do drugs alter the body's control systems? (7)
1. Attaching to a cell membrane and acting on specific site.
2. Interfere with ion passage through/across membrane.
3. Inhibit a membrane-bound enzyme and ion pumps.
4. Act on metabolic process within a cell.
5. Act outside the cell to change its environment.
6. Act inside a cell on cellular proteins or cellular constituents (amino acids).
Effective dose
ED50.
The dose that produces half of the maximal response for a specific drug.
Efficacy
Ability to produce a desired effect.
The ability of a drug to initiate a biological effect or stimulate its receptor in a way that produces a pharmacological response after it has bound itself to a receptor.
Excretion
The rate and method by which drugs or their metabolites are eliminated from the body.
Removal predominately occurs by way of urine formed in the kidneys.
Other routes: bile, saliva, sweat, tears, feces, breast milk, and exhaled air.
False substrate
A substrate that undergoes chemical transformation in the body to form abnormal product that subverts the normal metabolic pathway being targeted.
Think carbidopa and levodopa used in Parkinson's.
Generic name
A short name of a drug derived from the chemical name.
Think acetaminophen, fluoxetine.
Half-life
t1/2.
How long it takes for half of a drug to be eliminated from the bloodstream.
Lethal dose 50
LD50.
The dose at which 50% of a population of human test subjects would die from taking a drug or how long one should continue taking a drug in order to reach its toxic endpoint.
Estimates made using animal studies.
Metabolism
The process by which the body breaks down (metabolizes) and converts (biotransformation) drugs into inactive substances.
The primary sites for drug metabolism are the liver and enterohepatic recirculation, the kidney, and biliary excretion.
Primarily through one or more biochemical modifications, using specialized enzyme systems, resulting in a more lipophilic compound better able to be more readily excreted polar product.
Meta-analysis
The mathematical combination of the results of several studies.
Noncompetitive antagonist
Irreversible antagonist. The drug does not let go of its receptor.
A drug that binds to a receptor and stays bound; it cannot be displaced by increasing the concentration of agonists.
Pharmacodynamics
The study or science of the EFFECTS of medication on the body, including the actions and effects of drugs in relation to their chemical structure.
Pharmacokinetics
The study of how the body AFFECTS a drug OVER TIME.
5 parameters: absorption, distribution, metabolism, excretion, half-life (table 2-2).
Potency
A measure of the ability of a set dose of an agonist or antagonist to produce its maximum pharmacological effect.

Simply stated: potency is a measure of drug activity expressed in terms of the amount required to produce an effect of given intensity.
Sympathomimetic
Drugs that are capable of stimulating the sympathomimetic nervous system to produce the same physiological effects as its natural stimulants such as epinephrine.
Think terbutaline, salmeterol, albuterol.
Therapeutic index
A ratio of the LD50 to the ED50.
TI = LD50/ED50
Toxic dose 50
TD50.
Indicates the dose (exposure) that will produce signs of toxicity in 50% of animals being tested.
The larger the TD50, the more of the drug it takes to produce signs of toxicity.
Factors affecting absorption:
ADME
-Absorption
-Distribution
-Metabolism
-Excretion
Volume of distribution
An imaginary volume of where a drug goes after ingestion.
Helpful for understanding where a dug goes once ingested.
Dissolution
ionization (water soluble)
Non ionized
diffuse across lipid cell membrane
Bioavailability
Increases with IV administration, decreases with PO administration (same drug and dose = different amounts in circulation)
Describe how drug receptors work and explain their roles: (4)
1. receptor's affinity for the drug
2. quantity of receptors available and the amount of the drug presented to the receptor
3. efficacy of the drug
4. potency of the drug
(Affinity, Efficacy, Potency are defined earlier cards)
Differentiate between an agonist and an antagonist
Agonist = Activates cell receptors because they resemble a naturally occurring hormone, transmitter or enzyme. They mimic/induce the same response produced by the endogenous substance. They also have affinity and efficacy for a particular receptor.

Antagonist = They can resist degradation and act for longer periods of time than can the natural substances they are designed to mimic. They DO NOT turn on the receptor's natural effect. They only bind to it.
Examples of AGONIST:
1. Albuterol - bronchodilation
2. sympathomimetic drugs - they are drugs that stimulate the sumpathomimetic nervous system to produce physiological effects. They work at adrenergic receptor sites. (Think albuterol works at the beta-2 receptor to induce bronchodilation.)
3. NE stimulates beta-1 receptors on the SA node of the heart; it is used to increased HR naturally (like adrenaline does).
2 types of AGONISTS
1. Full agonist = agonist with maximal efficacy
2. Partial agonist = agonist that shows low degree of activation.
Examples of ANTAGONIST:
1. Beta Blocker (beta-andrenoreceptor antagonist) = blocks beta-1 at the SA node, effectively decreasing the HR.
2. Benadryl blocks histamine receptors
3. Naloxone (Narcan) blocks opiate receptors in the resp center and quickly reverses narcotic OD.
2 types of ANTAGONISTS:
1. Competitive = reversible= drug that competes with an agonist for binding to a receptor.
2. Noncompetitive = irreversable = drug binds to a receptor and stays bound, it can't be displaced by increasing the concentration of agonists.
Differentiate between a drug's efficacy, affinity, and potency
1. Affinity = strength and binding between drug and receptor.
2. Efficacy = ability of drug to initiate a biological or stimulate its receptor in a way that produces a pharmacological response AFTER it has been bound itself to a receptor.
3. Potency: measures the ability of a set dose of an agonist or antagonist to produce its maximum pharmacological effect.
Differentiate between a receptor-mediated drug activity and a second-messenger drug activity
Receptor- mediated = Receptor mediated endocytosis is an endocytotic mechanism in which specific molecules are ingested into the cell. The specificity results from a receptor-ligand interaction.

2. Second messengers are intracellular signaling molecules released by the cell to trigger physiological changes such as proliferation, differentiation, migration, survival, and apoptosis. Secondary messengers are therefore one of the initiating components of intracellular signal transduction cascades. (Examples of second messenger molecules include cyclic AMP, cyclic GMP, inositol trisphosphate, diacylglycerol, and calcium. )
Explain how ion channels, enzymes, and transporter systems behave as sites of drug activity
Ionic bonding
Van der waals bonding
Hydrogen bonding
Describe the significance of the BBB
Drugs tend to be poor at penetrating into the CNS because they are actively pumped out, are highly charged molecules, or have high molecular weight & can't pass through lipid membranes.
Non-ionized molecules that are NOT bound to plasma membranes can enter the brain easily because they are lipid soluable.
Ionized molecules CAN NOT.
What interrupts the BBB?
Inflammation - it allows substances that are normally impervious to enter the brain.
*PCN when treating bacterial meningitis
What is first pass effect?
Drugs enter the bloodstream from the GI tract, then enter the liver via the hepatic portal vein before entering the general circulation.
Why is first pass effect important?
It allows the liver to metabolize the drugs into less active or inactive metabolites/drugs before they are distributed throughout the body.
(ex. heroin is converted to morphine which is less potent)
Explain why a drug's potency is a factor in its dosing
A highly potent drug (fentanyl) evokes a larger response at low concentrations, while a drug of lower potency (codiene) evokes a small response at low concentrations. It is proportional to affinity and efficacy.
Describe how drug clearance, volume distribution, and half-life can be used to monitor pt therapy
Determines how quickly and to what extent a drug will appear at its target site of action, stay there, be neutralized and leave the body.
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