Basic Pharmacology Flashcards
What is a drug?
Any substance that alters physiology of the body (not food or nutrient)
Definition must consider intention (vitamin C - not a drug but has drug-like properties)
What is behavior?
Intake/processing information, integration of information, actions based on this processing, and many other things
Illicit vs. licit drugs
Illicit = illegal
Licit = legal
Abuse can’t be determined by legality → recreational (pleasure) vs. instrumental (socially-approved goal)
What is pharmacology?
Consists of two elements:
Pharmacodynamics - body’s biological response to drugs (what the drug does to the body)
Pharmacokinetics - movement of drugs throughout the body (what the body does to the drug)
What are the different methods of naming drugs?
Chemical name (i.e. 7-chloro-1)
Generic (nonproprietary) name (i.e. Diazepam)
Trade (proprietary) name (i.e. valium)
Street name (i.e. downers, vitamin V)
What units are dosages given in?
Milligrams (mg) - 1/1000 g
Keeps dosages constant in human adults, children, and other animals (less in humans than rodents)
What is a dose response curve?
A graph of a drug’s potency and effectiveness that tests different doses of a drug (plotted on log scale)
What is effectiveness?
Maximum effect at any dose
ED₅₀ - dosage effective in 50% of all cases
What is potency?
Dose required for efficacy
Lower ED₅₀ = high potency
Higher ED₅₀ = low potency
What is lethal dose?
The probability of adverse effects
LD₅₀ kills 50% of subjects
What is the Therapeutic Index (TI)?
TI = LD₅₀/ED₅₀ (higher TI = safer drug)
What is the Safety Index (margin of safety)?
More conservative version of TI
LD₁/ED₉₉ (lethal dose for 1%/effective dose for 99%)
What are the different drug effects (2)?
Primary effects - the reason a drug is taken (i.e. Advil is taken for fever reduction)
Side effects - an effect that isn’t directly related to the reason for taking the drug (i.e. Advil is also an anti-inflammatory)
What is Thalidomide and how does it demonstrate the different drug effects?
Thalidomide - mild sleeping pill
Marketed as “safe for pregnant women” → caused thousands of babies to be born with malformed limbs (drug tests don’t address all potential impacted populations)
What is a ligand?
A chemical that binds with a particular molecule
What is the difference between endogenous and exogenous?
Endogenous - from within the body
Exogenous - from outside the body
What is the difference between an agonist and an antagonist?
Agonist - activates receptor
Antagonist - inactivates or blocks receptor
Some drugs are partial agonists or partial antagonists
What are the different drug interactions (3)?
Antagonism - one drug diminishes the effectiveness of another drug
Additive effect - ED₅₀ decreases with drug A + drug B (compared to A alone)
Superadditive effect/potentiation - greater additive effect than what would be expected from adding A + B
What are the different elements of pharmacokinetics (ADME)?
Absorption - how it gets in
Distribution - where it goes
Metabolism - what affects it/how it breaks down
Excretion - how it leaves
What is a route of administration?
The way a drug gets into the body from the outside world; can use natural processes (ingestion, breathing) or artificial (injection)
What is parenteral administration?
Injection through the skin into various parts of the body using a hollow needle and syringe and must be in a vehicle (liquid)
What are the 4 common parenteral routes (in order of absorption)?
Intravenous (IV) or mainlining
Interperitoneal (IP) - into the cavity where the organs are
Intramuscular (IM)
Subcutaneous (SC or sub-q) - directly under skin layer
Common routes of administration rated from highest to lowest peaks in blood levels:
Intravenous (IV)
Intramuscular (IM)
IM - oil
Subcutaneous (SC)
Oral/”per os” (PO)
How do areas with more blood flow influence absorption?
Areas with more blood flow have faster absorption rates due to more capillaries (small vessels)
How are drugs absorbed through inhalation?
Absorbed from the air into lungs → distributed throughout the body very quickly (rich in capillaries)
Go directly to the brain without being processed in the liver
How do gases and smoke move through the body?
Gas moves from high concentrations (inhaled in lungs) to low concentrations (blood in the lung capillaries) → rapid diffusion
Blood concentration higher in the lungs than gas? → gas is exhaled
How does intranasal administration work?
Some absorbed through lungs, most absorbed in mucous membrane of sinuses → efficient, fast delivery to nervous system
What are the two potential routes of oral administration?
Swallow drug → digestive system
Entry through buccal (mouth) membranes → avoids digestive system
How does the digestive system absorb drugs?
Some is absorbed into the bloodstream in the stomach, most occurs in the intestines (food delays absorbtion)
Walls of intestines are lined with capillaries behind membrane of intestinal wall (drug must be able to be dissolved in lipid bilayer of membrane for absorption to occur)
How do you test the lipid solubility of drugs?
Equal parts water and oil → fixed amount of drug mixed in → drug levels measured in separated water and oil → very lipid soluble drugs are more concentrated in oil
How does the degree of ionization (polarity) impact lipid solubility?
Lipid soluble = non-ionized molecules (NaCl)
Hydrophilic = ionized molecules (Na⁺, Cl⁻)
More lipid soluble drugs = more absorption
More water soluble drugs = less absorption
What is the lipid solubility of different organs in the digestive system?
Stomach = non-ionized, thus absorbed
Blood = ionized, thus not absorbed back
Intestine = ionized, thus not absorbed
How does transdermal administration work?
Substances that are highly lipid soluble can be absorbed through the skin (slowest absorption method)
Absorbed locally → transported into systemic circulation
What is the difference in drug distribution based on lipid solubility?
Higher lipid solubility → concentrated in body fat outside the CNS (lower efficiency)
Drugs must be lipid soluble to get past the blood-brain barrier
Special transport systems allow non-lipid soluble drugs into blood
How does the blood-brain barrier keep drugs out of the brain?
Tight junctions prevent large pores → very few things can pass through
Fat-soluble molecules and molecules subject to active transport (i.e. glucose) can pass through
How are most drugs excreted?
Most excreted through liver and kidneys, some is excreted in feces, sweat, and saliva
What are the main functions of the kidneys?
Maintain salt-water balance (excrete excess water and unwanted substances in urine)
Filter blood and reabsorb good stuff (non-lipid soluble/ionized substances are filtered out unless they use a special transport system)
What does the liver do?
Molecules that enter are changed via enzymes (i.e. alcohol dehydrogenase changes alcohol into acetaldehyde)
What is metabolism?
The process of restructuring molecules
Produces metabolites (less active and less toxic than original state in most cases)
What do enzymes do?
Combine chemical substances or break them apart using active sites (lock and key) → allow reactions to occur
What are factors that alter drug metabolism?
Stimulation of enzyme system (one drug enters using one efficient enzyme system = fast metabolism)
Depression of enzyme system (2 drugs enter competing for same enzymes = slow metabolism)
Age (newborn and elderly = slowed drug metabolism)
What is the therapeutic window?
Level of a drug in blood changes over time due to constant absorption, filtering, and excretion → plot absorption and excretion to determine when a drug is most effective
