Pharmacology Flashcards
Define effective dose (ED50).
The dose of drug needed to induce the desired effect in 50% of the animals to which it is administered.
Define potency.
The concentration of the drug needed to achieve a pharmacological effect equal to 50% of Emax.
Define toxic dose (TD50).
The dose of a drug needed to induce toxic effect in 50% of the animals to which it is administered.
Define therapeutic index
TD50/ED50
The higher the therapeutic index, the safer the drug is considered to be.
What is the difference between zero order kinetics and first order kinetics?
Zero order kinetics: a constant amount of drug is being eliminated per unit time
First order kinetics: a constant proportion of drug is being eliminated per unit time
After you change the dose of a drug, how many half-lives are required for the new steady serum concentration to be achieved?
4-5 half-lives
After you stop a drug, how many half-lives are required for the drug to be fully eliminated from the body?
4-5 half-lives
What is the formula for loading dose calculation using desired concentration and volume of distribution?
Loading dose = Desired concentration x the volume of “central compartment”
Define first pass effect.
When the drug is given in different route (e.g. PO), the drug may be metabolized at certain location (most commonly liver) before reaching to the site of action and therefore the concentration of active drug is reduced.
Dose IV route always mean 100% bioavailability?
No. If a drug can be eliminated via the lung, the bioavailability may not be 100%.
Which phase of biotransformation does cytochrome P450 mainly involve?
Phase I
What is phase II biotransformation also called?
Conjugation phase
What are the 4 pathways of acetaminophen metabolism?
1) Sulfuric acid conjugation → bile & urine
2) Glucuronidation → bile & urine
3) Transformed and oxidized by cytochrome P450 system to NAPQI (toxic!!!) → react with glutathione to form mercapturic acid → urine
4) deacylation by hepatic microsomal carboxyesterases → para-Aminophenol (PAP) → conjugated with glutathione, sulfation, biotransformation through N-acetylation with N-acetyltransferase (NAT)
- Cats cannot do 2) because they don’t have glucuronyl transferase
What is isoproterenol?
Non-selective 𝜷 agonist
What is the MOA of Dantrolene?
Bind to the ryanodine receptor to depress excitation-contraction coupling in skeletal muscle.
Fill out the blank:
The minimum inhibitory concentration (MIC) is defined as “the lowest concentration of an antibiotic that will __________ of a given bacteria.”
inhibit the visible growth
Fill out the blank: MDR organism is defined as the microorganism that acquired non-susceptibility to _________.
At least one agent in three or more antimicrobial categories