Exam 1 - Pharmacokinectics Flashcards
A medicine or other substance which has a physiological effect when ingested or otherwise introduced into the body
Drug
The study of how a drug enters the body, circulates within the body, is changed by the body, and leaves the body
Pharmacokinetics
What are the 4 major pharmacokinetic steps of drug movement in the body
- Absorption
- Distribution
- Metabolism
- Excretion
The study of the biochemical and physiologic actions of drugs, and their mechanisms of drug action at the cell level and sub-cell level (what the drug does to the body)
Pharmacodynamics
What 4 characteristics of drug molecules influence whether a drug can cross a lipid membrane?
- Lipid solubility
- Degree of ionization (charge cannot cross)
- Molecular Size
- Shape
Weak acid in an acidic environment = ____
Weak acid in a basic environment =____
Weak base in acidic environment = ____
Weak base in a basic environment = ____
Lipid soluble
Water soluble (dissociates)
Water soluble (dissociates)
Lipid soluble
(lipid/water) soluble = non ionized (no charge)
lipid/water) soluble = ionized (polar
Lipid
Water
____ = drugs given by this route are placed directly into GI tract - ORAL/RECTAL
Enteral
____= administration bypasses the GI tract and includes various injection routes, inhalation, and topical drug administration
Parenteral
9 parenteral drug routes
- Inhalation
- Intravenous *** MOST RAPID/PREDICTABLE
- Intramuscular - slow
- Topical - local or systemic
- Subcutaneous
- Sublingual
- Transdermal - patch. more concentrated
- Intrathecal - epidural
- Intraperiotoneal - dialysis
T/F rectal (enteral) drug administration is poorly/irregularly absorbed from rectum
True
Describe rate of onset for:
- IV
- IM
- Patch
- Sublingual
- Subcutanerous
- Inhalation:
- Ointment/spray
- Oral
- Controlled rate/continuous/rapid/predictable
- delivers large quantity, slow sustained due to high blood flow through skeletal muscles
- continuous delivery, slow release
- rapid delivery
- slow onset
- rapid
- dose controlled
- usually enteral, cheapest/easiest
4 ways molecules cross membranes
- Diffusion - lipid soluble drugs/passive/high to low
- Filtration - small molecules -> membrane pores
Specialized transport for large/ionized/water soluble molecules - Facilitated diffusion - carrier
- Active transport - ATP
3 factors that influence rate of drug movement
- Physiochemical factors
- Solubility
- Route of administration
T/F the closer the site of administration is to a blood vessel, the faster a drug can be absorbed
True
Drugs that are administered orally pass from the stomach to the intestine to the portal veins to liver
“first pass effect” of drug metabolism after oral absorption (metabolize drugs to inactive forms before they have the change to enter the systemic circulation
What type of drugs bypass the first pass effect?
drugs given parenterally - direct to bloodstream
____= the fraction of the administered drug that becomes available in the plasma. FREQUENTLY influenced by the “vehicle” of the drug (difference between generic/brand name drugs)
Bioavailability - only IV administration gives 100%
FDA mandates that generics must have ___% of the availability of the parent compound
90
2 forms in which drugs are in the blood
- Bound to plasma proteins - no effect
2. Free - can pass cell membranes and exert desired effect
____= most drugs cross easily; lipid-soluble drugs cross most easily
Placenta
____= drugs that can cross this barrier are lipid-soluble, very small molecular weight/size, and exert effects on the CNS
Blood Brain Barrier
Drug Redistribution - movement of the drug from the site of ____ to nonspecific sites of ____. Duration of action can be affected by redistribution from one ____ to another. If redistribution occurs between specific sites and nonspecific sites, the drugs action will be ____. Example: An “____” agent is administered to induce sleep before anesthesia for surgery. After a few minutes, the action is terminated, bc the drug has been redistributed from the CNS via the plasma to skeletal muscle to finally ___ ___ in the body.
Action Action Organ Terminated Induction Fat Deposits
_____= converts lipid soluble drugs to water soluble metabolites (so kidneys can easily excrete and metabolites are less likely to bind to plasma proteins or store in fat)
Biotransformation aka drug metabolism