Pharmacology - General Principles Flashcards
What kinds of things do drugs target?
- Proteins on/in cells (g-proteins, ion channels, transmembrane receptors, intracellular receptors, or adhesion proteins)
- enzymes
- or can be free-floating chemical messengers
What is a type 1 dose-response relationship?
The graph represents the relationship between a dose and the number of receptors it binds to
With a type 1 dose-response curve, what does an antagonist chemical do to a curve/dose for an agonist drug?
It causes the curve to shift right, meaning the drug must be at a higher concentration to get the desired effect
With a type 1 dose-response curve, what happens to the agonist’s curve if there’s a noncompeting antagonist thrown into the mix?
The curve shortens, meaning the drug simply cannot bind to as many receptors
What is a type 2 dose-response relationship?
The graph represents the relationship between dose and the desired efficacy
How do you calculate therapeutic index (TI)?
Lethal dose 50/Effective dose 50
What is Emax on the dose-response curve?
It is the maximum number of receptors/efficacy that the drug can handle, regardless if the dose is raised
What does ADME stand for?
absorption, distribution, metabolism, excretion
How are drugs absorbed if taken orally?
Through the intestines and then the hepatic portal venous system
How are acids/bases distributed in the body?
weak bases tend to stay in the very acidic tissues, and weak acids tend to stay in the very basic tissues
What is an example of a distribution barrier in the body?
blood-brain barrier
Where are most drugs metabolized?
The liver, by cytochrome P-450 enzyme
Where are most drugs excreted?
The kidneys, by glomerular filtration, active tubular secretion, or passive tubular transfer
What are phase 1 metabolism techniques that the body uses?
oxidation, reduction, or hydrolysis
What are phase 2 metabolism techniques?
conjugation, meaning a chemical constituent is attached to the drug molecule
How do you calculate doseage?
Cp0 x Vd = initial plasma concentration, multiplied by volume of distribution
What does the curve look like for zero-order kinetics? First order?
Zero-order = linear line w/ negative slope First-order = concave line that slowly approaches x-axis
Do zero-order kinetic drugs or first-order have a greater risk for drug accumulation?
Zero-order
How can drug-drug interactions occur?
A drug could compete for receptors, or they can alter the metabolism of another drug
What is induction of drug metabolism?
It means a drug increases enzyme metabolism (usually P-450 in the liver) which speeds up the metabolism of another drug. Causes efficacy to drop.
What is inhibition of drug metabolism?
Means a drug competes for the enzyme or totally inhibits the enzyme’s action - this causes a drug to remain in the body longer and can be bad
How do genetic effect drugs?
A person’s enzyme profile determines the rate of metabolism/clearance of a drug
What is an idiosyncratic reaction?
an adverse reaction due to genetic changes usually involving a change in enzyme activity
What happens if you give diazepam/triazolam to a pt taking clarithromycin or itraconazole?
Increases sedation because the clarithromycin and itraconazole are metabolism inhibitors of CYP-450
What happens if you give tetracyclines to someone taking oral antacids?
reduced absorption/efficacy of tetracyclines
What happens if you give aspirin to someone taking probenecid?
decreased efficacy of probenecid
What happens if you give aspirin to someone already taking methotrexate?
increases methotrexate toxicity
What happens if you give local anesthetic to someone taking cholinesterase inhibitors?
antagonism of cholinesterase inhibitors, and reduced efficacy with myasthenia gravis patients
Why should you not give benzocaine or procaine to someone with an NADH-methemoglobin reductase deficiency?
Chance for methemoglobinemia
Aspirin, Primaquin, or sulfonamides should NOT be given to someone with what genetic condition? Why?
Glucose-6-phosphate dehydrogenase deficiency, because it can cause hemolytic anemia
Barbiturates and sulfonamides should NOT be given to pt with this condition?
abnormal heme synthesis, because it can cause porphyria
Procaine and other ester anesthetics should not be given to people with what condition?
low plasma cholinesterase activity, because it can can local anesthetic toxicity
A pt with abnormal muscle calcium homeostasis should not be given what?
Nitrous oxide or succinylcholine, because it can cause malignant hyperthermia
A pt with prolonged Q-T interval should not be given what?
some antipsychotics and antiarrhythmias, because it can cause torsades de pointes
At what step of the drug testing phase does a drug hit market?
After step 3. Step 4 is post-marketing surveillance
What are drug pregnancy risk categories?
They are categorized as A, B, C, D, and X. A being no effects to baby during pregnancy, and X being that there were abnormalities or death with baby.
What did the Pure Food and Drug Act do in 1906?
forbade the adulteration and mislabeling of drugs
What did the Harrision Narcotic Act do in 1914?
regulated opiates and cocaine
What did the Food, Drug, and Cosmetic Act do in 1938?
Mandated safety of drugs, and established FDA as the enforcer
What was the Durham-Humphrey act of 1952?
Made certaind drugs prescription-only
What was the Orphan Drug Amendment of 1983?
Provided incentive for drugs developd for rare diseases
What did the FDA Modernization Act do in 1997?
New regulations for ephedrine, pseudoephedrine, and phenylpropanolamine
