BASIC CONCEPTS IN PHARMACOLOGY

 

 

I   Basic Concepts

            A.  Pharmacodynamics

                        1.  definition

                        2.  general mechanisms

                                    a.  receptors and specificity

                                    b.  agonists

                                    c.  antagonists

                        3.  pharmacodynamics of individual classes of drugs

                                    a.  site (or sites) of drug action  (ex: narcotic analgesics)

                                                1.  therapeutic effects

                                                2.  side effects

                                    b.  specific mechanism of drug action   (ex: local anesthetics)

            B.  Posology

                        1.  definition

                        2.  dose - response relationship

                                    a.  “ceiling effect”

                                    b.  potency and ED 50 (effective dose 50)

                                    c.  efficacy

                        3.  time - response graph

                                    a.  minimal effective concentration

                                    b.  onset of action

                                    c.  duration of action

                                    d.  termination of action

                        4.  loading dose vs. maintenance dose

            C.  Toxicology

                        1.  Lethal dose 50  (LD 50)

                        2.  Therapeutic Index   (TI)

                        3.  adverse drug effects

                                    a.  teratogenic

                                    b.  carcinogenic

                                    c.  drug idiosyncrasy

                                    d.  drug allergy

                                                1.  symptoms

                        4.  abuse potential

                                    1.  Federal Controlled Substances Act, 1970

                                    2.  drug schedules

 

 

By the end of this unit you should be able to:

    -  distinguish between pharmacodynamics and posology

    -  describe and diagram what a drug must do to have an effect in the body, i.e. receptors and specificity

    -  explain the difference between an agonist and an antagonist

    -  discuss how a single drug can have therapeutic effect and side effects and even toxic effects at the same time

    -  define effective dose 50 (ED50), potency, ceiling, and efficacy

    -  explain the purpose of a dose-response curve

    -  interpret dose-response curves:  compare "the ceiling", ED 50, and potency of different drugs

    -  explain the purpose of time-response curves  

    -  interpret a time-response curve:  identify minimal effective concentration, onset of action, duration of action, and termination of action

    -  compare a loading dose and a maintenance dose

    -  define lethal dose 50 (LD50)

    -  define and determine Therapeutic Index  (TI) for an individual drug if you are given its ED50 and LD50

    -  discuss the different categories of adverse drug affects:  teratogenic, carcinogenic, allergenic, and idiosyncratic

    -  state the purpose of the Controlled Substances Act

    -  compare the different drug schedules I thru V

 

 

D.  Drug forms

                        1.  liquid

                                    a.  solution and suspension

                                    b.  aqueous and alcoholic

                        2.  solid / semi-solid

                                    a.  powders

                                    b.  tablets

                                                1.  slow or delayed-release

                                                2.  enteric-coated

                                    c.  capsules

                        3.  suppositories

                        4.  cream vs. ointment

                        5.  transdermal patches

                        6.  beads or pellets

            E.  Routes of administration:  advantages and disadvantages

                        1.  enteral

                                    a.  oral

                                                1.  sublingual variation

                                    b.  rectal

                        2.  parenteral

                                    a.  intravenous  (IV)

                                    b.  intramuscular  (IM)

                                    c.  subcutaneous  (SC)

                                    d.  intra-thecal (epidural)

                                    e.  intra-arterial

                                    f.  inhalation

                                    g.  topical  (vs. transdermal)

 

           

                   

                 

                         Is this enteral or parenteral drug delivery ?  

                         What type of injection is this ?

 

 

            F.  Pharmacokinetics

                        1.  definition:  factors determining the active concentration of drug

                        2.  drug absorption = entrance into bloodstream

                                    a.  dissolution

                                    b.  multiple barriers

                                    c.  membranes

                                                1.  passive transport:  diffusion (with concentration gradient)

                                                            a.  size

                                                            b.  lipid solubility

                                                            c.  ionized vs. un-ionized form 

                                                                        1.  pH effects

                                                2.  active transport

                                    c.  bioavailability

                        3.  drug distribution (via bloodstream)

                                    a.  concentration gradient

                                    b.  plasma proteins

                                    c.  blood flow variation

                                    d.  capillary permeability; blood-brain barrier 

                                    e.  placenta

                                    f.  storage (bone, fat)

                        4.  drug metabolism:  biotransformation

                                    a.  liver

                                                1.  first-pass effect                    

                                                2.  DMMS (drug microsomal metabolizing system)

                                                            b.  activation and inactivation

                                                            c.  enzyme induction

                                    b.  form for elimination

                        5.  drug elimination

                                    a.  renal

                                    b.  GI excretion

                                    c.  respiratory exit

                                    d.  saliva, sweat, tears

                                    e.  breastmilk

                        6.  Blood-drug levels

                                    a.  half-life                    

                                    b.  effects of liver and kidney disease

 

 

At the end of this unit of study, you should be able to:

    - list the different forms drugs can take and how they are used

    - discuss the advantages and disadvantages of enteral and parenteral drug administration

    - explain why a drug might be delivered subcutaneously and not intravenously or intramuscularly

    - define pharmacokinetics

    - list the 4 major factors affecting the pharmacokinetics of a drug

    - describe what a drug must do to enter the bloodstream

    - define simple diffusion

    - discuss how the size and solubility of a drug affects its absorption into the blood

    - define ionized and unionized form of a drug

    - explain what form  a drug must be in to cross the membrane (be absorbed)  and why

    - explain what form a drug must be in to cross the membrane to be excreted and why

    - define bioavailability and explain how to increase it

    - discuss the factors which affect drug distribution from the blood to the receptors in the tissues

    - explain what "biotransformation" refers to in pharmacology

    - discuss the "first pass effect"  and the DMMS and how it affects dosage of drugs

    - list the ways drugs are eliminated

    - explain "half-life" of a drug

    - discuss why liver and kidney disease may require a different drug dosage

   

     

 

 

                                                   

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