EXAM 1 STUDY GUIDE
Principles Of Pharmacology
Galen College of Nursing
, Pharm Exam 1 Study Guide
Unit 1
Drug Phases
Pharmacokinetic phase
-Absorption, Distribution, Metabolism, Excretion
•Pharmacokinetic Phase: is the process of drug movement through the body necessary to achieve drug action and includes
absorption, distribution, metabolism and excretion
•Pharmacodynamic Phase: is the study of the effects of the drug on the body ex. receptor binding, post receptor effects and
chemical reactions
Pharmacokinetic Phase
•Absorptions is the movement of the drug through the blood stream after its administration
•Disintegration is the breakdown of the oral drug into smaller particles
•Dissolution is the time it takes the drug to disintegrate and dissolve to become available for absorption
•Absorption Methods
-Passive transport
*Diffusion: is across the semipermeable membrane high to low concentration.
*Requires no energy
*It stops when the concentration is equal on both sides of the membrane
*In oral drugs GI (higher concentration) moves to the blood stream (lower concentration(
-Facilitated diffusion
*Same principle as passive but requires a carrier protein to move the drug
-Active transport
*Requires carrier and energy to move the drug against the concentration gradient
-Pinocytosis
*Taking a bit out of the particles and brining them into the cell
-Lipid soluble drugs and nonionized drugs are absorbed faster than water soluble and ionized drugs
•Factors affecting absorption:
-blood circulation (poor circulation,vasoconstrictors, shock, disease)
-pain, stress, exercise
-food texture, fat content, temperature
-pH
-route of admin(IV, oral, IM)
•Factors affecting oral meds
-first pass effect-liver via portal vein
-bioavailability
•Drug movement from GI tract to liver: from mouth to the gut to portal vein and then the liver, drugs may be metabolized to an
inactive form and excreted reducing the amount of the active drug available to achieve desired effect. This is first pass effect (first
pass metabolism)
•Bioavailability: is the percentage of the drug left for activity. May be affected by absorption and first pass metabolism for oral
drugs. Bioavailability is always less than 100%
Factors affecting bioavailability
-Drug form
-Absorption
-First pass metabolism
-Route of admin
-Gastric mucosa and motility
-Admin with food and other drugs
-Changes in liver metabolism
•Drug metabolism (bio transformation):
-the process of body chemically changing drug into a form to be excreted
-half-life
-loading dosage
,•Drug excretion (elimination)
-Kidneys: Creatinine Clearance, BUN, Glomerular filtration Rate (GFR is lower in older male and females due to decreased
muscle mass)
-Liver (bile)
-Feces
-Lungs
-Saliva, sweat, breast milk
•Drug distribution: is the movement of the drug from the circulation to tissues
-Protein binding: if med is highly protein bound and the older adult does not have protein available then it will not be
available to use in body
-Drugs unbound are Free Drugs
-Volume of drug distribution
-Competition over protein biding sites leads to more free drug
-Low plasma protein levels cause more free drugs floating around
-Low albumin same thing (elderly considerations)
-BBB (blood brain barrier); water soluble drugs do not cross BBB
-You want to be careful with those who are pregnancy some drugs cause the placenta and cause same: teratogenic drugs
Pharmacodynamics: study of the way drugs affect the body
Primary effect: Desirable effect
Secondary effect: can be desirable or undesirable
Example: Benadryl primary effect: treat allergies secondary effect: CNS depression (sedation)
Drug Response Relationship
Potency: The amount of drug needed to elicit specific physiological response
-if physiological response at very low concentration this means low potency
Therapeutic Index: relationship of the drug between the therapeutic drug dose and the toxic drug dose, this is different for every.
Usually a dose is the average for most people but expect exceptions
-Onset: time it takes for a drug to reach minimum effective concentration
-Peak: highest concentration in blood
-Duration: length of time take for drug to exert a therapeutic effect
-Below therapeutic response = under dose making it ineffective
-Above therapeutic response= overdose and may be toxic
Therapeutic monitoring:
Peak drug level: highest plasma concentration of a drug
Trough drug level: lowest plasma concentration of the drug
Receptor theory: drugs bind to receptors
-to activate a receptor
-to produce a response
-to inactivate a receptor
-Drugs can compete for the same receptor site; if one is bound the other is going to be free.
-Four receptor families:
1.cell membrane-imbedded enzymes
2.ligand-gated ion channels
3.g-protein-coupled receptor systems
4.transcription factors
, Agonist: they AGREE , the work and activate to produce better response
-activate receptors
-produce desired response
-pushers/stimulators
Antagonist: is AGAINST, if something is too much, they will slow down or stop
-prevent receptor activation
-block response
-preventers/stimulators
Nonspecific: multiple receptor sites
Non selective: works on multiple receptors
Cholinergic receptors: eye, heart, blood vessels, stomach, bronchus, and bladder
Mechanism of drug action:
-Stimulation
-Depression
-Irritation
-Replacement
-Cytotoxic action
-Antimicrobial action
-Modification of immune status
Side Effects
-Secondary effects: expected, continue meds, common, chronic conditions, genetics, ethnicity, age, all of these may
influence secondary effects, side effects should gradually decrease
-Adverse reactions: mild to severe usually more severe than side effects, stop meds or pt can become worse, rare,
unexpected, undesirable effects with normal dose, adverse effects can increase
-Drug toxicity: drug levels exceed therapeutic range, overdose or drug accumulation, underlying condition, age, genetics
Pharmacogenetics
-Biologic variations: study of genetic factors influencing individual response
-Tolerance: decreased drug responsiveness over time
-Tachyphylaxis: acute rapid decrease in drug responsiveness regardless of time
-Placebo effect: drug response not attributed to chemical drug properties
Pharmacodynamics
-Drug interactions: altered drug effect due to interaction with another drug
-Pharmacokinetic interactions: changes occurring in absorption, distribution, metabolism and excretion
-Additive: sum of effects of two drugs
-Synergistic: effect is much greater than effects of either drugs alone
-Antagonistic: one drug reduces or blocks effect of other drug
-Drug nutrient interactions: food may increase, decrease or delay drug response
-Drug laboratory interactions: drug may cause misinterpretation of test results
-Drug induced photosensitivity:
-skin reaction cause by sunlight
-photo-allergic reaction, immune mediated, delayed, may result from a larger dose of the drug
-Photo-toxic reaction: is when a photo-toxic drug interacts with skin and produces damage, it is not immune mediated
-Grapefruit has a lot of interactions with drugs do not give grapefruits juice
-MAOIs with tyramine rich foods, like cheese, wine, organ meets, yogurt, beer, sour cream and bananas AVOID
-Drugs can block, decrease, increase the absorption of other drugs
-Increasing or decreasing gastric emptying time
-changing gastric pH
-forming drug complexes