IASM 80 81: Drug Basics II Flashcards
Drugs, during absorption, should be in their ________ state. During excretion, they should be in ________ state.
Drugs, during absorption, should be in their lipophilic state. During excretion, they should be in water-soluble state.
In enzyme CYP2A6
2 refers to
A refers to
6 refers to
In enzyme CYP2A6
2 refers to family
A refers to sub-family
6 refers to isoform
During Drug Metabolism, there are 2 phases
What are they? What do they include?
Phase I Reactions, give an example
Phase II Reactions, give an example
Phase I: Functionalization Reactions- Changing the functional group of the drug, resulting in loss of pharmacological activity
Example: Use of hydrolytic enzyme: Hydrolysis of esters and amides to alcohol and amine group
Phase II: Conjugation Reactions- Form covalent linkage between functional group on drug with endogenously derived conjugates
Example: Glucuronidation (Increase water solubility to promote excretion)
Conjugate example: Glucuronic Acid
How should the dose change if the person is a
- Extensive metabolizer
- Poor metabolizer
How should the dose change if the person is a
- Extensive metabolizer: higher dose is required
- Poor metabolizer: we should lower the dose
Order of Reactions
For Zeroth Order, what is the rate equation?
For First Order, what is the rate equation?
For Second Order, what is the rate equation?
Zeroth Order: r = -k
First Order: r = -kc
Second Order: r = -kc^2
Basically, r = -kc^n
Order of Reactions
For Zeroth Order, what is the linear equation?
For First Order, what is the linear equation?
For Second Order, what is the linear equation?
Zeroth Order: c = -kt + C0
First Order: ln c = -kt + ln C0
Second Order: 1/c = kt + 1/C0
Order of Reactions
For Zeroth Order, what is the half-life expression?
For First Order, what is the half-life expression?
For Second Order, what is the half-life expression?
For which order of reaction, half-life is independent on C0?
Zeroth Order: C0/2k
First Order: ln2/k
Second Order: 1/C0k
For which order of reaction, half-life is independent on C0?- First order
What is volume of distribution
How to calculate it
A higher volume of distribution means that the plasma concentration of drug is _____ (high/low), so that the drug has ________ (increased/decreased) tendency to leave the circulation and stay in tissues.
The fluid volume required to contain all the drug in the body, at the same concentration as the blood or plasma
Calculation: Amount of drug administered / Plasma Concentration of the drug
(Use units to think: (mg)/(mg/L)=L
A higher volume of distribution means that the plasma concentration of drug is LOW, so that the drug has INCREASED tendency to leave the circulation and stay in tissues.
Mix and Match, Volume of Distribution
When drug tend to bind to plasma proteins, the volume of distribution would be _______ to the plasma volume
When drug is well-distributed to the tissue instead of staying in the circulation, volume of distribution would be _________ the plasma volume
Mix and Match, Volume of Distribution
When drug tend to bind to plasma proteins, the volume of distribution would be similar to the plasma volume
When drug is well-distributed to the tissue instead of staying in the circulation, volume of distribution would be much greater than the plasma volume
Bioavailability- How to calculate?
Drugs administered through which route always has 100% bioavailability?
Bioavailability- How to calculate?
AUC (Route of administration) / AUC (Intravenous)
*(If it is administered orally/ If it is administered IV-ly)
Drugs administered through which route always has 100% bioavailability? Intravenous
In the DRUG SENSE
How to calculate Clearance
Blood flow (Arterial drug conc - Venous drug conc) / Concentration of drug
Therapeutic Window is the difference between…
Therapeutic Window is the difference between…
Minimal effective concentration for adverse response - Minimal effective concentration for desired response
What is the equation of relation of the following, with 1st Order Kinetics?
- Bioavailability
- Clearance
- Concentration of drug in circulation
- Dose
1st Order Kinetics:
Bioavailability x Dose = Clearance x Concentration of drug in circulation
At steady state, what is the equation to link the below
- Bioavailability
- Clearance
- Dosing Rate
- Steady state concentration
Bioavailability x Dosing rate = Clearance x Steady state concentration
*Concept: Rate of administration = Rate of elimination
How to calculate Loading Dose
(Steady State concentration x Volume) / Bioavailability
