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Vet Pharmacology MT1
Cal Poly SLO, Burd, Midterm 1. Includes pharmacokinetics and pharmacodynamics.
(D) = Define | Answer |
---|---|
(D) Dose | The amount of a drug administered at one time to achieve the desired effect |
(D) Loading dose | The initial dose of drug given to get the drug concentration in the therapeutic range in a very short period of time. |
(D) Maintenance Dose | The dose of drug that maintains or keeps the drug in the therapeutic range. |
(D) Total Daily Dose | The total amount of drug delivered in 24 hours. |
(D) Dosage | The amount of drug per animal species' body weight or measure. |
(D) Dosage interval | How frequently the dose is given (bid, sid, etc) |
6 causes of drug toxicity | Outright overdose Relative Overdose (too much for THIS animal) Accidental Exposure Side Effects Interaction with other drugs Incorrect Treatment |
(D) Drug Distribution | The physiological movement of drugs from the systemic circulation to tissues. |
(D) Bioavailability | the degree to which a drug is absorbed and reaches the circulation |
(D) Induce | To increase the rate of metabolism of an enzyme system |
The movement of molecules from an area of high concentration to an area of low concentration is known as | Passive Diffusion |
In what form do the majority of acidic drugs exist in an acidic environment? | NONionized |
Drug affinity is the | strength of binding between a drug and its receptor |
True or false: Giving fluids to an animal will increase the excretion of the drug. | True |
True or False: Thin animals with low plasma protein levels require more drug than animals of normal weight. | False |
The four steps of pharmacokinetics: | 1) Absorption 2) Distribution 3) Metabolism (or biotransformation) 4) Excretion |
(D)Effective Dose | amount of drug that produces desired effect in at least 50% of animals. ED50 |
(D) Lethal Dose | Amount of drug that produces death in 50% of animals (LD50) |
(D) Therapeutic Index | Margin of Safety LD50 ----- ED50 |
(D) Therapeutic Range | Drug concentration in the body of the animal that produces desired effect at target tissue with no signs of toxicity. |
Five main things that affect therapeutic range | Rate of Entry Absorption Distribution Metabolism Excretion/Elimination |
What should we use to determine drug dose when animal is obese? | Lean Body Mass |
What are the 3 major factors to keep a drug in the therapeutic range? | Route of Administration Dose Dose Interval (frequency) |
(D) Parentral | All administration routes other than the GI tract EX) IV, IM, SC |
(D) Non-Parentral | Administration given via GI tract EX) oral (po, per os) |
Do lipophilic or hydrophilic drugs pass through cell membranes better? | Lipophilic. |
If a drug is more hydrophilic, how does this affect the drug's elimination? | Increased hydrophilic = increased elimination |
(D) Passive Diffusion | The movement of drug molecules from an area of high concentration to an area of low concentration. |
Drugs that move through passive diffusion must be... | Small in size, lipophilic, and nonionic. |
(D) Lipophilic | Fat loving. Chemicals that dissolve in fat or oils. |
The intestinal mucosa has lipid-rich cell membranes, which allows... | lipophilic drugs to be well absorbed from the gut via passive diffusion. |
Intramuscular drugs are deposited in the fluid surrounding the cells and must diffuse through fluid to reach the capillaries. So, IM drugs should be ______ for rapid absorption. | hydrophilic |
The ionization or charge of a drug depends on... | the pH of the liquid in which it is immersed and the pH of the drug. |
Hydrophilic drugs are usually a) ionized or b) nonionized | hydrophilic - ionized |
Lipophilic drugs are usually a) ionized or b) nonionized | lipophilic -NONionized |
(D) Facilitated diffusion | passive diffusion that uses a special carrier molecule (specialized carrier proteins) |
(D) Drug Absorption | the movement of the drug from the site of administration into the fluids of the body that will carry it to its site(s) of action. |
What determines the bioavailability of a drug? | The percent of drug that gets from where it is administered to the bloodstream. |
Intravenous drugs are ____% bioavailable. | 100% |
Drugs that are partially absorbed have a bioavailabilty of... | less that one. |
The lower the bioavailability of the drug, the more or less drug there is in the tissue? | Less, because there is less in the bloodstream. |
Factors that affect bioavailability: | -Blood supply to target area. -Surface area of absorption (increased surface area means more space for absorption to take place) -Mechanism of drug absorption (EX -diffusion vs active transport) -Drug dosate |
(D) first pass effect (or hepatic first pass) | Where the drug passes directly to the liver, where the drug is mostly metabolized to an inactive form of the drug for excretion. |
On the pH scale, the lower numbers indicate ____ and the higher numbers indicate ____. | Lower - acid Higher - Base (alkaline) |
(D) Biotransformation | the chemical alteration of drug molecules by the body cells of patients to a metabolite that is an activated, inactivated, and/or toxic form. |
Weak acids become more ionized as the pH of the environment ____ | increases. |
Weak bases become more ionized as the pH of the enviornment ____ | decreases |
(D) Ion Trapping | Drugs can pass from one compartment to another that may have a different pH. When the drug changes compartments, it may change ionization, and become trapped in it's new environment. |
Oral drugs must be ____ to penetrate the GI mucosa. They must also be ____ to dissolve in the membrane. | Lipophilic small |
(D) Distribution | the physiological movement of drug form the systemic circulation to the tissues. |
Factors that affect drug distribution | Membrane permeability Tissue perfusion Protein Binding Volume of Distribution |
(D) Fenestrations | Small holes between cells that allow drug molecules to move in and out of capillaries. |
Why is it important to note that the blood-brain barrier and capillaries of the CNS have no fenestrations? | This means only very lipophilic drugs can enter. |
Acid drugs in an alkaline environment tend to be ____. | Charged |
Alkaline drugs in an acid environment tend to be ____. | Charged |
Acid drugs become more ____ at a pH more acidic than it's pKa. | Lipophilic |
Alkaline drubs become more lipophilic at a pH more ____ than its pKa. | alkaline |
(D) pKa | The pH at which a drug has a 1:1 ration of ionized drug to nonionized drug. |
Acid drugs become more _____ when placed in an acid environment. | nonionized |
Any acid drug placed in an acidic pH environment will produce more drug molecules in the _____ (____) form. | nonionized (lipophilic) |
Placing an acidic drug in any alkaline pH environment will produce more molecules in the ____ (____) form. | ionized (hydrophilic) |
Placing an alkaline drug in an acid environment will produce more drug molecules in the ______ (____) form. | ionized (hydrophilic) |
An alkaline drug placed in an alkaline environment will produce more drug molecules in the ____ (____) form. | nonionized (lipophilic) |
(D) Tissue perfusion | The relative amount of blood supply to an area or body system. |
Increased tissue perfusion = increased or decreased drug absorption. | INCREASED (rapid absorption) |
Why is the equilibrium established between the concentration of bound and unbound drugs important> | It allows bound drugs to be released from its binding sites when plasma concentrations of unbound drug diminish. |
What is the principle protein in systemic circulation? Where is it produced? | Albumin Liver |
If an animals has liver disease, what happens to protein binding? Why? | Less proteins available for binding, because albumin is produced in the liver. Less protein = more free drug, which means more drug to target tissue. Potential toxicity can occur. |
(D) Volume of Distribution | How well a drug is distributed throughout the body based on the concentration of drug in the blood. |
Increased protein binding = more or less free drug available. | Less |
The larger the volume of distribution, the ____ the drug concentration in the blood after distribution. | Lower |
Usually, a metabolite is more _____ (therefore more _____) and less likely to pass through membranes. | hydrophilic ionized |
Four main ways that drugs undergo biotransformation: | Oxidation reactions Reduction reactions Hydrolysis Conjugation (addition of the glucuronic acid molecule, which makes the drug more water soluble) |
Primary site of biotransformation.... | Liver |
The goal of biotransformation is to make drugs more ... | water soluble so that they can be excreted in the urine. |
4 ways in which drugs interact with each other. | Altered absorption Competition for plasma proteins Altered excretion Altered metabolism |
Poor nutrition yields inadequate ______ | plasma proteins |
Increased body temperature increase or decreases rate of drug metabolism? | increases |
The most important routes of drug elimination are the ____ and _____. | Liver and kidney |
The rate of glomerular filtration depends on _________ | blood pressure. |
The higher the volume of blood going through the glomerulus, the higher the blood pressure of the capillaries of the glomerulus, and so.... | the greater the number of particles that could potentially be filtered. |
The three ways that drugs are eliminated by the kidney: | glomerular filtration, tubular secretion, and tubular reabsorption |
(D) Tubular secretion | active transport across the convoluted tubule membrane that moves certain molecules from blood into the urine filtrate. |
Tubular reabsorption of drugs occurs in ... | the loop of Henle |
Tubular reabsorption depends on | lipid solubility and molecule size |
During tubular reabsorption, a drug that is _____ _____ will have increased reabsorption. | lipid soluble |
Drugs that are weak acids tend to be better excreted in more ____ urine. | Basic |
Drugs excreted by the liver usually move by passive diffusion from ____ into the liver cell. | blood |
_____ drugs that enter the duodenum will reenter the bloodstream and go back to the liver. | Lipophilic |
_____ drugs entering the duodenum will most likely become part of the feces and be eliminated. | Hydrophilic |
(D) Half-life | the time required for the amount of drug in the body to be reduced by half its original level. |
The steady state of a drug is.... | the point at which drug accumulation and elimination are balanced. |
How will dehydration affect elimination? | Dehydrated animals have less vascular fluid volume and so have decreased pressure in the vessels being filtered by le glomeruli. |
Low blood protein levels will lead to... | less protein-bound drug (more free drug), which may be filtered through the glomerulus before it has had time to work. |
Do high affinity drugs or low affinity drugs bind more tightly to a receptor | High affinity |
(D) Affinity | the strength of binding between a drug and its receptor |
(D) Agonist | a drug that binds to a cell receptor and causes action |
(D) Antagonist | A drug that inhibits or blocks the response of a cell when the drug is bound to receptors. |
(D) Competitive antagonist | Competes with the agonist for the same receptors |
A noncompetitive antagonist binds to a site different than the agonist's binding site and ... | mechanically alters the agonist's receptor which results in a "roadblock" to the action of the agonist. |
(D) Clearance | rate of elimination for a drug with respect to the concentration of drug in the fluid compartments. |
Drug dosage rate = plasma clearance x _________ | Bioavailability at steady state |
Drugs excreted by the liver (hepatic elimination) usually move by passive diffusion from ___ to ___. Then, they are secreted into ____. This is then secreted into the ____. | the blood into the liver cell. Bile Duodenum |
Renal Clearance rate = | Urinary concentration x Urine flow rate --------------------------------- Plasma concentration |
Half life * ___ = steady state | 4.7 |
(D) Efficacy | the ability of a drug to induce a response |
(D) Potency | the amount of drug that is required to elicit a specific response |
A full agonist will elicit the maximum response and hence _____ _____. | Maximum efficacy. |