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Pharm CH 1

Pharmaceutic, Pharmacokinetic, and Pharmacodynamic Phases

What are the three phases of a drug reaction in the order that they happen? pharmaceutic, pharmacokinetic, and pharmacodynamic
When is there no pharmaceutic phase? when the drug is administered parenterally by subcutaneous (subQ), intramuscular (IM), or intravenous (IV) routes
Describe the second phase of a drug reaction. four processes in order absorption: distribution: metabolism (or biotransformation): excretion (or elimination):
Define active absorption. the movement of drug particles from the GI tract to body fluids using a carrier such as an enzyme or protein to move the drug against a concentration gradient. Energy is required for active absorption.
What happens in the 1st phase of a drug reaction? drug becomes a solution so that it can cross the biologic membrane
What happens in the third phase of a drug reaction? a biologic or physiologic response results
What is an adverse reaction? They are a range of untoward effects (unintended and occurring at normal doses) of drugs that cause mild to severe side effects, including anaphylaxis (cardiovascular collapse).
Define agonists. Drugs that produce a response.
Give an example of an agonist and why it's classified as so. Epinephrine (Adrenalin)-- stimulates beta1 and beta2 receptors, so it is an agonist.
Define antagonists. Drugs that block a reaction.
Give an example of an antagonist and why it's classified as so. Atropine-- blocks the histamine (H2) receptor, thus preventing excessive gastric acid secretion.
What is the IC50 ? the antagonist drug concentration required to inhibit 50% of the maximum biological response.
How can effects of an antagonist can be determined? by the inhibitory (I) action of the drug concentration on the receptor site Pg 8
What is bioavailability? a subcategory of absorption that represents the percentage of the administered drug dose that reaches the systemic circulation.
How do water soluble drugs pass through the membrane? Water-soluble drugs need a carrier, either enzyme or protein, to pass through the membrane. Pg 4
Which drugs are absorbed faster? drugs that are lipid soluble and nonionized are absorbed faster
Which drugs are absorbed slower? water-soluble and ionized drugs
What factors alter bioavailability? 1. The type of pill consumed 2. route of administration consumed(rectal, topical, oral) 3. GI mucosa and motility 4. food and other drugs 5. changes in liver metabolism caused by liver dysfunction.
What is the creatinine clearance? Name something similar to it. Common tests used to determine renal function. The blood urea nitrogen (BUN) is another test that can be used to test for renal function.
Which drugs are filtered through the kidneys? Pg 6 free unbound drugs, water-soluble drugs, and drugs that are unchanged.
Does urine pH influence excretion of drugs? Yes. Acidic urine promotes elimination of weak base drugs, and alkaline urine promotes elimination of weak acid drugs.
What is disintegration? It is part of the pharmaceutic phase and is the the breakdown of a tablet into smaller particles.
What is Dissolution? the dissolving of the smaller particles in the GI fluid before absorption.
Enteric-coated drugs in the gastric acid of the stomach... will resist disintegration disintegration does not occur until the drug reaches the alkaline environment of the small intestine. The coating protects the medication from the acidic GI tract.
What is Pharmacokinetics? the process of drug movement to achieve drug action.The four processes are absorption, distribution, metabolism (or biotransformation), and excretion (or elimination).
Define passive absorption. a type of absorption that uses diffusion and doesn't require energy
Define Active Absorption. requires a carrier such as an enzyme or protein to move the drug against a concentration gradient. This method requires energy.
Define First pass-effect aka hepatic first pass--when a drug travels to the liver first to be metabolized.
Define Distribution. the process by which the drug becomes available to body fluids and body tissues.
What influences distribution? blood flow, the drug's affinity to the tissue, and the protein-binding effect
Define free drugs. drugs not bound to proteins
Define Metabolism. is the process by which the body inactivates or biotransforms drugs.
Define Half-Life. The time it takes for one half of the drug concentration to be eliminated.
What influences half-life? (t^1/2)Metabolism and elimination affect the half-life of a drug.
Define pharmacodynamic. the study of the way drugs affect the body.
Define Onset of action. the time it takes to reach the minimum effective concentration (MEC) after a drug is administered.
Define Peak Action. when the drug reaches its highest blood or plasma concentration.
Define Duration of Action. the length of time the drug has a pharmacologic effect.
What is a time-response curve? A curve that evaluates three parameters of drug action: the onset of drug action, peak action, and duration of action.
Define Protein-binding effect. The ability for drugs to bind to proteins in plasma inside the blood stream.
Define Receptor families. Proteins found in the cell membrane that contain binding sites for drugs.
What are the four receptor families and how are they different? Kinase-linked receptor, G protein–coupled receptor systems Ligand gated ion channels, Nuclear receptors.
What is a ligand binding domain? the site on the receptor at which drugs bind
Kinase-linked recptor. The ligand-binding domain for drug binding is on the cell surface. The drug activates the enzyme (inside the cell), and a response is initiated.
Ligand-gated ion channels. The channel spans the cell membrane and, with this type of receptor, the channel opens, allowing for the flow of ions into and out of the cells. The ions are primarily sodium and calcium.
G protein–coupled receptor systems. There are three components to this receptor response: (1) the receptor, (2) the G protein that binds with guanosine triphosphate (GTP), and (3) the effector that is either an enzyme or an ion channel.
Nuclear receptors. Found in the cell nucleus (not on the surface) of the cell membrane. Activation of receptors through the transcription factors is prolonged. With the first three receptor groups, activation of the receptors is rapid.
Nonspecific drugs Drugs that affect various sites but the same receptors
Nonselective drugs Drugs that affect various receptors or have properties of nonselectivity.
The four categories of drug action include... (1) stimulation or depression, (2) replacement, (3) inhibition or killing of organisms, and (4) irritation.
Therapeutic index (TI) estimates the margin of safety of a drug through the use of a ratio that measures the effective (therapeutic) dose(ED) in 50% of people (ED50) and the lethal dose in 50% of people (LD50). The closer the ratio is to 1, the greater the danger of toxicity.
Formula for Therapeutic index (TI) LD50/ED50
therapeutic range Pg 9 Aka therapeutic window---the level of drug between the minimum effective concentration in the plasma for obtaining desired drug action and the minimum toxic concentration (the toxic effect).
Pharmacogenetics the scientific discipline studying how the effect of a drug action varies from a predicted drug response because of genetic factors or hereditary influence.
Peak drug level the highest plasma concentration of drug at a specific time. Peak drug levels indicate the rate of absorption.
trough drug level lowest plasma concentration of a drug, and it measures the rate at which the drug is eliminated. Trough levels are drawn immediately before the next dose of drug is given, regardless of route of administration.
Digitalization the process by which the minimum effective concentration level for a drug is achieved in the plasma within a short time.
Side effects physiologic effects not related to desired drug effects
Adverse reactions more severe than side effects.
Another name for Toxic Effects and how to find out how much medicine to give... Aka toxicity---can be identified by monitoring the plasma (serum) therapeutic range of the drug.
Tolerance a decreased responsiveness over the course of therapy
tachyphylaxis to a rapid decrease in response to the drug---"Acute tolerance"
placebo effect a psychological benefit from a compound that may not have the chemical structure of a drug effect.
Protein-Bound drug causes inactive drug action/response
Created by: MBO










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