Block 1 - Respiratory Med Chem Flashcards
What are esters metabolized to?
carboxylic acid
How are histamine receptors similar to muscarenic?
Contains ionic and h-binding sites
Describe the SAR of 1st gen Antihistamines
What are the classes of 1st gen antihistamines?
- ethanolamine ethers
- tricyclic
- piperazine
- alkylamines
Why does ethanol amine have short half lives?
N-dealkylation
What gives doxylamine antimuscarinic effects?
CH3 on X and ionic binding of 3 amine
How does alkyl amines different from other 1st AH?
longer duration of action, less sedation
What is the primary metabolism of alkyl amines?
N-dealkylation
What are piperazine?
Hydroxyzine -> cetirizine
anticholinergic ADRs
What gives tricyclic AH LA?
S brings more lipophilicity to rings
What makes tricyclic different than antipsychotics phenothiazines?
Antipsychotics are unbranched and have a substituent on ring
What makes 2nd gen AH differ from 1st?
- Less anticholinergic
- Less CNS/ sedation
- More hydrophilic
- long half-life
- Varied structures
Why does Fexofenadine have less CNS activity?
effluxes out of BBB by the p-gp
Folds on itself to bind to H1 receptor
Why should you drink fruit juice with allegra?
Juices inhibit OAT1A2 from absorbing drug into the blood stream
What drug is pseudo irreversible? why?
Zyrtec because will strongly bind to receptor and slowly release from it
Why does Zyrtec not have CNS activity?
Folds on itself like Allegra and removed by p-gp
What is the difference between loratadine and desloratidine?
Des is more potent with a longer half-life, a metabolite of loratadine.
Both are removed by p-gp by do not fold
What are the characteristics of olopatadine?
- Zwitterion
- Topical
- Long duration and rapid onset
- Inhibits mediators and mast cell stabilizer
- Minimal must effect from N and COOH
What is the MAO of azelastine?
- Mast cell stabilizer
- LTC4 inhibition
- Antihistamine
What is the MOA for cromolyn?
- Mast cell degranulation inhibitor
Why is cromolyn polarity absorbed?
Contains 2- charges that must both be neutralized to pass through membrane
What are the endogenous steroids?
Hydrocortisone and cortisone
Out of the 2 endogenous steroids which is active?
hydrocortisone
What makes a steroid active?
- ketone on 3 and 20
- alkene on 4
- OH on 11, 17, 21
At what positions do steroids bind?
beta
What is the difference between glucocorticoids and mineralocorticoids?
G: glucose homeostasis, anti-inflammatory
M: sodium and water retention
Why are ketone and OH groups important for steroids?
to form H bond at GC receptor sites
What is the exception on the OH 21 on steroids?
Can be Cl or thioester
What make steroids a prodrug?
Ketone on 11 or 21
What makes a steroid more acidic?
F on 9a or 12a
What are the mechanism of inactivating a GC steroid?
- Loss of 21 OH
- Ring A reduction
- C-17 oxidation
- C11 keto enol isomerization
Why is the purpose of esterfying GC?
- increase or decrease lipophilicity
- Increase log P (lipo) -> longer duration of action and more local activity
- prodrug
What portion of the steroid can be esterized?
C21 (easiest)
C17 (slower more hindered)
C11 (highly hindered so no activity)