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Intro to Pharm
Dose response relationships, pharmacodynamics/kinetics, R's, signal transduction
| Question | Answer |
|---|---|
| What is clinical pharmacology? | The science of drugs and their clinical use...focus on application of pharm principles in the real world. It has a broad scope, from the discovery of new target molecules to the effects of drug usage in whole populations. |
| What are pharmacotherapeutics? | The use of drugs to diagnose, prevent, & treat disease (or to prevent pregnancy). |
| What is the definition of drug effectiveness? | The drug elicits responses for which it has been administered. |
| What is the generic name for tylenol + dolane + panadol, etc.? | Acetaminophen |
| What is the average length of time for preclinical testing and what are two characteristics? | Average length of time is 2.6 years & characteristics include toxicities/pharmacokinetics/effects explored using animal testing & application to FDA for Investigational New Drug/begin clinical trials. |
| What is the average length of time for clincal testing? | Average length of time is 5.6 years. |
| What are the characteristics of phase I of clinical testing? | Healthy volunteers, 20-80, metabolism & effects |
| What are the characteristics of phase II of clinical testing? | Patients, 200-300, therapy & dosage range |
| What are the characteristics of phase III of clinical testing? | Patients, 100s to 1000s, safety & effectiveness, next apply to FDA for New Drug Application |
| What are the characteristics of phase IV of clinical testing? | General use, large population |
| What are the limitations of clinical testing procedures? | women of child-bearing age not included, children, failure to detect all adverse effects |
| What are two advantages to OTC drugs? | increased access, less expensive |
| What are two disadvantages to OTC drugs? | self-care, drug interactions |
| What are pharmacokinetics? | The branch of pharmacology dedicated to the fate of substances administered externally to living organisms. The study of drug ABSORPTION>DISTRIBUTION>METABOLISM>EXCRETION (absorption, distribution, elimination) |
| What are pharmacodynamics? | The study of a drug at the site of action and the EFFECT ON THE BODY. (Systemic effects & cellular effects) |
| What is toxicology? | The study of harmful effects of chemicals including drugs, environmental toxins, & poisons |
| Why utilize pharmacokinetics? | better care of pt., decreased toxicity of drugs, better judgment of pharmacodynamic effect, define & eliminate drug interactions, individualize therapy (optimal dose-response relationship) |
| Why utilize pharmacodynamics? | to obtain maximal efficacy (individual variation, status change, drug interactions, misdiagnosis, poor compliance, environmental variables) |
| If there is a net electrical charge, chan drugs cross the membrane? | The drug cannot cross the membrane. |
| Acid ionizes in ______media; base ionizes in _____media. | ionizes in bacic media; ionizes in acidic media |
| What are the characteristics of first order kinetics? | Linear, constant PERCENT of drug is removed per unit time, concentration DEPENDENT |
| What are the characteristics of zero order kinetics (alcohol)? | NONlinear; saturable, constant AMOUNT of drug is removed per unit time, concentration INdependent |
| What is the sequence of pharmacokinetics? | Dose-->(absorption, distribution, metabolism, elimination)> concentration in blood)-->concentration at site of action-->effect |
| Absorption depends on: | Product formulation, disease state, drug interactions, first-pass effect, pH |
| What is the first-pass effect? | The phenomenon of drug metabolism whereby the concentration of a drug is greatly reduced before it reaches systemic circulation. The liver metabolizes much of oral drugs (take 50mg, only 25mg active); reduces bioavailability. |
| What are alternative routes of drug administration that avoid the first-pass effect? | Suppository, intravenous, intramuscular, & sublingual all allow drugs to be absorbed directly into systemic circulation. |
| What are the three enteral (GI) routes of drug administration? | Oral, sublingual, rectal |
| What are four parenteral routes of drug administration? | inhalation, injection, topical, transdermal |
| What are the disadvantages of oral drug administration (easiest/most common route)? | Drugs must be lipid soluble, first-pass effect (significant amt drug absorbed in liver before reaching site of action) |
| What are advantages/disadvantages of sublingual drug administration? | Advantages: bypass first-pass effect; Disadvantages: amount absorbed is limited (drugs must go through oral mucosa) |
| What are advantages/disadvantages of rectal drug administration? | Advantages: treatment of hemorrhoids/local conditions; Disadvantages: absorbed poorly or incompletely |
| What are the advantages/disadvantages of inhalation drug administration? | Advantages: apply medications to bronchial tissue-anesthetics/asthma; Disadvantages: ability to predict concentration that reaches lungs limited |
| What are the disadvantages for all injected drug administration methods? | Possible infection & problems with patient self-administration |
| What are the advantages/disadvantages of intravenous injection drug administration? | Advantages: ER situations; Disadvantage: appearance of large titers of drug |
| What are the advantages/disadvantages of intra-arterial injection drug administration? | Advantage: focuses the administration of drugs; Disadvantage: dangerous & difficult procedure |
| What are the advantages/disadvantages of subcutaneous injection drug administration? | Advantages: local response such as local anesthesia or slow prolonged release of medication; Disadvantage: amount of drug that can be injected is small |
| What are the advantages/disadvantages of intramuscular injection drug administration? | Advantage: rapid effect while avoiding sudden increases in drug concentration; Disadvantage: local pain and prolonged soreness |
| What are the advantages/disadvantages of intrathecal (direct to spinal cord) injection drug administration? | Advantage: Narcotic analgesics to spinal cord; disadvantage: painful and dangerous |
| What are the advantages/disadvantages of topical (not absorbed through skin) drug administration? | Advantages: nasal spray, eye drops, dermatological interventions; Disadvantages: adverse systemic effects if inadvertently absorbed into body |
| What are the advantages/disadvantages of transdermal (absorbed through dermal layers) drug administration? | Advantages: slow, controlled release of drug (patches); Disadvantage: must be able to penetrate skin & must not be degraded by enzymes in skin |
| What is bioavailability? | Extent to which the drug reaches systemic circulation (IV= 100%, oral= first-pass so not 100%) |
| Distribution of drugs in the body depends on what three things? | Drug characteristics (lipid solubility, molecular size, ionized vs unionized), binding to plasma protein, blood flow to tissues absent in abcesses or tumors |
| What is volume of distribution? | body space into which a drug can diffuse; volume in which the amount of drug would need to be uniformly distributed to produce the observed blood concentration |
| What is a loading dose? | an initial higher dose of a drug that may be given at the beginning of a course of treatment before dropping down to a lower maintenance dose; most useful for drugs eliminated from the body slowly; 70kg man = 42L |
| Volume and location of asprin/morphine/lithium? | Asprin: 8.4L, retained in bloodstream; Morphine: 420L, concentrated in tissue; Lithium: 42L, distributed uniformly |
| What occurs during phase I of drug metabolism? | Must make the drug hydrophilic (make polar for elimination so body does not reabsorb) |
| What occurs during phase II of drug metabolism? | Cytochrome P450 oxidases (genetically different in each person) |
| What are the three events during elimination? | filtration (protein binding & molecular size & charge); passive transport (depend on pH & lipid solubility); active transport |
| Weak acids are reabsorbed in more ____ urine, weak bases are reabsorbed in more _____ urine (used to treat overdoses) | acidic; alkaline |
| What is clearance (Cl)? | amount of blood or other fluids from which all drug is removed per unit time |
| Define half-life (t1/2) | dosing regimen to achieve steady-state concentration of drug in blood; 4-5 half lives to get steady state concentrations |
| Describe a dose response curve. | x: dose (Log scale); y: response; very low dose: no response-->threshold to see response -->reach maximal efficacy where no increase in response occurs; provide information about dose range over which drug is effective |
| Describe a graded dose response curve. | Dose (log) vs. Effect; note EC50, Emax; involves one patient; |
| What is the EC50? | The dose in a patient that will result in half the maximal effect (Emax is maximal efficacy). |
| What is potency? | If this is increased, the drug requires a lower dosage to produce the same effect as a higher dosee of a second drug. It is determined by affinity for its receptor & the ability of a drug to reach its site of action |
| How is efficacy determined? | By the type of interaction with the receptor & limitations on the amount that can be administered |
| Describe a quantal dose-response curve. | biological variability among people -->populations; y-axis ends in -ing; Dose (log)vs. %people responding; normal curve; hyperreactive (low dose) to hyporeactive (high dose) |
| List some variations in drug response. | alteration in drug concentration reaching receptor, tolerance, changes in components of response after drug binds to the receptor |
| What is idiosyncratic biological variability? | Infrequently observed drug effect. |
| What is hypersensitivity (describing biological variability)? | allergic reaction to a drug |
| What is tolerance (describing biological variability)? | time related loss of response to a drug (weeks-->months) |
| What is tachyphylaxis related to biological variability? | tolerance that happens very quickly (minutes-->hours) |
| Describe the cumulative dose-response curve. | Dose vs. % responding; ED50 curve & TD50 curve with limits of beneficial/toxic |
| What is ED50? | Median effective dose, 50% population responds in a specified manner |
| What is TD50? | Median toxic dose; 50% of population exhibits adverse effects |
| What is LD50? | Median lethal dose; 50% animals studied result in death |
| What is the therapeutic index? | TI= TD50/ED50 (in animal studies LD50 can replace TD50); indicates drug safety; greater TI is considered safer |
| Therapeutic Index examples: acetaminophen (?); asprin (?); meperidine (demerol) (?); methotrexate (chemo agent) (?) | acetaminophen (27); asprin (1); meperidine (demerol) (8); methotrexate (chemo agent) (1) |
| What are some factors that alter pharmacokinetics/pharmacodynamics? | age (liver/kidney function, total body water/fat), sex, pregnancy, body size, genetic factors, body size, genetic factors, drug interactions, disease processes, drug characteristics |
| What are some basic properties of drug receptors? | drugs bind to receptors to produce effects; drug + receptor = drug - receptor complex-->response; when a drug binds it mimics or blocks the action of endogenous regulatory molecules |
| What are some basic functions of receptors (proteins with unique binding sites)? | Interact with endogenous and exongenous compounds; interpret a signal from the drug and transfer that information into effect |
| Can drugs give cells new functions? | NO...they alter pre-existing processes by exploiting the fact that compounds can be administered from an external source to achieve receptor interaction & possible cellular effect |
| List some factors that determine interactions between drug and receptors. | size and shape of drug, electrostatic attraction, configuration of the receptor, ability of the drug to reach the receptor |
| What is affinity? | It refers to the attraction between a receptor and a ligand |
| What does efficacy refer to? | The ability of a ligand to bind to the receptor, activate it, and lead to some physiological response |
| What is an agonist? | a drug that binds to the receptor and causes a response, has both efficacy and affinity (partial agonist has affinity but lacks full efficacy) |
| What is an antagonist? | a drug that binds to the receptor without a response, has only affinity, classified as competitive or noncompetitive |
| What is a competitive antagonist? | a drug that competes for the same binding site as the agonist and can be overcome (reversible) |
| What is a noncompetitive antagonist? | a drug that is irreversible, and cannot be displaced by the agonist; effect long lasting; must recycle receptor complex to reactivate |
| What are three classifications of receptors? | intracellular, membrane bound (Ion channel linked), G-protein coupled |
| In the cell signal cascade, the signals allow the cell to.... | recieve a message, translate message through transduction |
| What are some examples of second messengers? | cAMP, cGMP, NO, DAG, IP3 |
| What are the steps in signal transduction? | A ligand binds to the receptor--> receptor propagates the signal --> proteins are turned on & mobilize second messenger molecules -->second messengers activate other proteins that carry the signal further --> physiological response --> termination |
| In terms of receptor regulation, an increase in stimulation does what to receptor function? | decreases receptor function (decreased stimuulation= increased receptor numbers and sensitivity) |
| What are some factors involved in drug interactions? | polypharmacy, intensified therapy, intensified side effects, decreased therapy, decreased side effects, unique response |
| What are some mechanisms of drug-drug interactions? | direct chemical/physical interaction, pharmacokinetic interaction, pharmacodynamics, combined toxicity |
| What are some possible drug-food interactions? | decreased absorption, increased absorption, grapefruit juice, increase toxicity (MAO inhibitors & tyramine), meal times, herbal supplements |
Created by:
mpost51
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