Exam 1 Flashcards
Schedule I
- highest potential for abuse
- NO accepted medical use in US or lacks safety for use in tx in US
- eg) heroin, marijuana
Schedule II
- high potential for abuse
- HAS a currently accepted medical use
- abuse may lead to severe psychological or physical dependence
- eg opiates (morphine, oxycodone, methadone), amphetamines (ritalin, adderall), cocaine
Schedule IV
- currently accepted medical use in US
- abuse may lead to limited physical or psychological dependencies relative to III
- benzos
Schedule III
- less abuse potential than I or II
- accepted medical use
- abuse may lead to moderate/low physical dependence or high psychological dependence
Schedule V
- low potential for abuse
- some can be sold in limited amounts without rx
Where to look for Drug Information
lexi-comp, MICROMEDEX, package, URI pharm library
Where do drugs come from (4)?
-plants/natural products, synthetic, semi-synthetic, human pool
Drug Testing Phases (7)
- compound discovery/”bench”
- animal phase
- Human phase I, II, III
- FDA approval with patent
- human phase IV (post-marketing phase)
Human Phase I
- determine effects, safe dosage, pharmacokinetics
- small number (<1 year
Human Phase II
- assess drugs effectiveness in treating a specific disease/disorder
- limited number (200-300) with target disorder
- 2 years
Human phase III
- assess safety and effectiveness in larger pt population
- large number (1000-3000)
- double/single blinding, placebo controls
- 3 years
Human phase IV (post-marketing phase)
- monitor any problems after NDA approval
- general pt population
- indefinite
Pharmacotherapeutics
-area of pharm that refers to use of specific drugs to prevent, treat, or diagnose a disease
Pharmacokinetics
-how body deals with drugs in terms of absorption, distribution, metabolism, excretion
Pharmacodynamics
- what the drug does to the body
- biochemical and physiological effects and mechanism of action
Enteral methods
-oral, sublingual/buccal, rectal
Parenteral methods
-inhalation, injection, topical, transdermal
Drug Absorption
entrance of drug into bloodstream
Drug factors affecting absorption (5)
-dosage form, drug water solubility, drug lipid solubility, drug particle size, drug concentration
Physiologic factors affecting absorption
-biologic/cell membranes, body “compartments”, cell membrane phospholipid bilayer
Lipid Bilayer
- hydrophilic tails, hydrophobic tails
- SMALL, UNCHARGED particles will pass
- small/charged and large/uncharged will not
Bioavailability
percentage of administered dose that is absorbed into systemic circulation
Factors affecting bioavailability (5)
- how administered
- where administered
- drug properties
- properties of the environment
- additional barriers
ADME
Absorption
Distribution
Metabolism
Excretion
Distribution
-after drug gains access to bloodstream, it is distributed to the organ/tissues of the body
Factors affecting Drug distribution (4)
- tissue permeability
- blood flow
- binding to plasma proteins
- binding to subcellular components
BBB
- additional lipid barrier that protects the brain by restricting the passage of electrolytes and similar water soluble substances
- drugs must have a certain degree of lipid solubility to penetrate
Most likely to penetrate BBB?
- small, uncharged, lipophilic
- eg) heroin, alcohol, benzo, meth
Plasma protein binding
- plasma proteins (esp albumin) assist in transport of hormones and vitamins
- only the UNBOUND portion of the drug is able to exert pharmacologic activity. remainder will continue to circulate
- 80% of most drugs will bind at some level
Blood Flow
- diff parts of body receive diff amounts of blood
- liver, kidney, heart, and brain have largest blood supply, therefore exposed to largest amount of drug
Volume of Distribution (Vd)
- Vd = amount administered / plasma concentration
- not physical volume, refers to size of compartment necessary to account for total amount of the drug in the body if it were present throughout in the same concentration found in plasma
Drugs that are activated with metabolism are called ______.
Pro-drugs
Kidney prefers ___ , _____ molecules
ionized, water soluble
Biotransformation
chemical aleration of drugs and foreign compounds in the body (phase I)
DMMS function
takes lipid-soluble drugs and prepares for excretion via renal system
First-pass effect
- drugs taken orally are absorbed through GI tract into portal circulation. Drug goes to liver BEFORE body. many drugs are inactivated by liver
- if drug is significantly metabolized, can reduce amount of active drug that reaches circulation
enzyme induction
when used repetitively, some drugs may increase enzyme activity. This may lead to faster metabolism of the drug and shorter duration of action (eg barbituates)
enzyme inhibition
will slow metabolism of all other drugs metabolized by the enzyme system and increase duration and intensity of drug
common pathways of drug excretion
-kidney/renal, liver/hepatic, lungs/pulmonary
Clearance (CL)
- ability of the body to remove drug from blood or plasma
- expressed as volume per unit time (eg ml/min)
- amount of drug removed depends on plasma concentration as well as clearance
entero-hepatic recirculation
- drug secreted into bile, may go into feces
- some drugs reabsorbed, process may be repeated
periodic measurements of plasma levels can help establish ________ for the drug
therapeutic range
plasma half-life (t 1/2)
time required for the plasma concentration of a given drug to fall to 1/2 its original level
-dependent on CL and Vd
Why is establishing half-life important?
kidney and liver disease
Loading dose
- try to get the person into therapeutic range quickly
- many drugs require loading dose to do this effectively
- a large initial dose of a substance or series of such doses given to rapidly achieve a therapeutic concentration in the body
Maintenance Dose
- the amount of drug required to keep a desired mean steady-state concentration in the tissues
- usually drop from loading dose to maintenance dose