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35 Cards in this Set

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Pharmacology
study of drugs, interactions with living systems, understanding physical, chemical properties, effects in the body, use of drugs, understanding how drugs are absorbed, distributed, metabolized and excreted.
Clinical Pharmacology
study of drugs in humans
Therapuetics
Pharmacotherapeutics): use of drugs to diagnose, prevent or treat disease, medical use.
Drug Names
1. Chemical name: chemical description

2. Generic name: non-proprietary name, given by United States Adopted Name Council.

3. Trade name: proprietary, created by drug companies, name approved by the FDA.
Major Properties of an Ideal Drug
1. Effectiveness: elicits the intended response.

2. Safety: does not produce harmful effects.

3. Selectivity: produces only the response for which it is given.
Therapeutic Objective
Provide maximum benefit with minimum harm.
Factors Determining the Intensity of Drug Responses
1. Administration: drug dosage, route of administration, timing of administration.

2. Pharmacokinetics: how the body affects the drug. Four pharmacokinetic processes: absorption, distribution, metabolism and excretion.

3. Pharmacodynamics: how the drug affects the body. Pharmacodynamic processes involve drug-receptor binding followed by the events that lead to the response.

4. Individual Variation:
a. physiological factors
b. pathophysiology
c. genetic factors
Pharmacokinetics
1. Absorption: mov’t of the drug from its site of administration into blood
2. Distribution: drug mov’t from blood to interstitial space of tissue and into the cells.
3. Metabolism: enzymatic processes that alter the drug
4. Excretion: movement of drug and metabolites out of the body.
Drug Transport Across Cell Membranes
1. Direct penetration: crosses membrane by penetrating through it. Lipid soluble.

2. Transport systems: carry the drug across the membrane. Selective. P-glycoprotein - transports drugs out of cells

3. Passage through channels and pores: very small to pass through.
Absorption
Mov’t of drug from its site of administration into the blood.
Bioavailability
extent to which a drug is absorbed and transported to the target tissue.
Factors that affect drug absorption
a. rate of dissolution: how easily drug dissolves. dissolves easy = quicker absorption.

b. surface area: the larger the surface area the quicker the drug will be absorbed.

c. blood flow: absorbed quicker from sites with high blood flow

d. lipid solubility: drugs with high lipid solubility are absorbed quicker

e. pH partitioning: difference in the pH of the plasma and pH at the site of admin, greater the difference the more easily absorbed.

f. site of absorption: absorption vary depending on the site of admin, route.
Routes of Administration
a. intravenous: administered directly into the blood stream

b. intramuscular: injection into muscle, easily absorbed

c. subcutaneous: injection into subcutaneous tissue.

d. oral: absorbed from the stomach or the intestine. Barrier to absorption is the epithelial cells, transporter P-glycoprotein
Advantages/Disadvantages of Intravenous
advantages: rapid onset, tight control over drug levels, can use large am’t of fluid disadvantages: dangerous – too fast, can’t take it back, inc risk of infection, cost
Advantages/Disadvantages of Intramuscular/Subcutaneous
advantages: used for meds that do not dissolve well, depot prep
disadvantages: painful, damage to local tissue, nerve damage.
Oral absorption influenced by
1. food or delayed gastric emptying
2. drug interactions
3. coating
4. solubility of the drug, pH
Advantages/Disadvantages of Oral
advantages: convenient, easier to use, less expensive.
disadvantags: inactivation or destruction of the drug, GI irritation, absorption variable from pt to pt.
Oral formulations
1. tablets: mixture of drug plus binders and fillers

2. enteric-coated preparations: coated so will dissolve in intestines but not stomach. The coating protects drug or protect the stomach

3. sustained release preparations: capsules filled with coated spheres that contain the drug. coatings dissolve at variable rates

e. other: topical – applied to the skin, eyes, nose, ears, vaginally, rectally, inhalation
Distribution
Mov’t of drugs through the body
1. blood flow to the tissues: Drugs delivered by blood stream and rate of delivery determined by blood

2. ability of drug to exit the vascular system: exit at the capillary beds, easily pass between capillary cells except at:
a. blood brain barrier: protects the brain from toxic substances. tight junctions between the capillary cells so through the cells – lipid soluble, med with transport system

b. placenta: protective barrier. lipid soluble can pass

3. ability of drug to enter cells: lipid solubility and the presence of a transport system. some drugs do not cross cell membrane – bind with receptors.
Metabolism
enzymatic alteration of the drug – referred to as the biotransformation. Occurs in the liver – the hepatic microsomal enzyme system. P450 system
Effects of Drug Metabolism
a. accelerated renal drug excretion: unable to excrete lipid soluble drugs, metabolism converts lipid soluble drugs into compounds easier to excrete.

b. drug inactivation: convert active compounds to inactive forms
c. inc. therapeutic action: inc effectiveness of some drugs by converting into more active form

d. activation of drugs: inactive compound (prodrug) into an active form.

e. inc. or dec. toxicity: dec. in toxicity occur when drug converted into inactive form. Inc. occur when drugs transformed into toxic substances.
Factors that influence Metabolism
a. age: infants sensitive to drugs until liver matures

b. induction of drug metabolizing enzymes: drugs cause liver to produce drug-metabolizing enzymes through induction. Induction inc metabolism of drugs -> inc doses needed to maintain therapeutic levels.

c. first-pass effect: rapid hepatic inactivation of a drug. To prevent use other routes than po.

d. nutrition: Cofactors needed for metabolism.
e. drug competition: compete with each other for metabolism if use
Steps in Drug Excretion
a. glomerular filtration: All drugs except those bound to albumin are filtered through the glomerular membrane.

b. passive tubular reabsorption: lipid-soluble drugs reabsorbed into the blood. Non-lipid soluble drugs (ions, polar) remain in the tubules and excreted in the urine.

c. active tubular secretion: Active transport systems pump drugs from blood into the urine. P-glycoprotein, pumps for organic acids/bases
Factors that Affect Renal Drug Excretion
a. pH dependent ionization: can speed up excretion of drugs. Changing pH of the urine causes ionization of drugs - reabsorption dec, excretion inc.

b. competition for active tubular transport: competition can delay excretion and prolong the effects of the drug.

c. age: infants kidneys not fully developed. Elderly – decline in renal function
Plasma Drug Levels
to regulate drug responses. Adjust up or down.
MEC
minimum concentration that is effective – anything below it is not effective.
Toxic concentration
toxicity occurs
Half-Life
time required for amount of drug in body to dec by 50%. Drugs with short half-lives = excreted quickly, long half-lives = excreted more slowly. Half-life determines dosing interval – the time between doses. Long half-life = long time between doses. Short half life = interval between doses shorter
single dosing
plasma levels go up as drug is absorbed. Drug therapeutic at MEC then it will be therapeutic. Plasma levels dec when metabolized and excreted.
multiple dosing
accumulation of drug in the body
plateau
drug level constant – 4 half lives
loading dose
big dose to get their therapeutic level up quickly
maintenance dose
to keep them at therapeutic level
peak
highest level of drug
trough
above minimum therapeutic level