Opioids Flashcards
What are the 2 classes of alkaloids?
Phenanthrene alkaloids
Benzyl isoquinoline alkaloids
What drugs are phenanthrene alkaloids?
Morphine
Codeine (prodrug)
What drugs are benzyl isoquinoline alkaloids?
Papaverine
Noscapine
Which of the 2 classes have analgeic effects?
Phenanthrene alkaloids only
What is a prodrug?
Administered in an inactive or less than fully active form that is through a metabolic process
typically hydrolysis of an ester via esterase activity
We use prodrugs to improve what?
ADME
Bioavailability
Side effects profile
Which drugs mentioned in lecture are prodrugs?
heroin
codeine
How can you increase activity of morphine?
- add alkyl group on C17 (longer than ethyl, no longer than 6C)
- add phenethyl > activity than benzene ring
- saturated double bond between C7 and C8
How can you modify morphine to reduce toxicty while retaining analgesic effects?
Add acetyl group to C6 (instread of OH)
Epimerize C6 OH from a to B
How does heroin’s structure differ from morphine?
acetyl groups instead of OH at C3 and C6
T/f codeine is more active than morphine
false!
Codeine is less active due to methoxy group on C3
Difference between OH at C3 vs C6
OH at 3: attached to phenyl group, more acidic, better leaving group = faster hydrolysis
OH at 6: attached to alkyl group
What are the chiral centers located in morphine?
5Ra
6Sa
9R
13S
14R
How are the morphine rings fused together?
B/C: cis
C/D: trans, C built off equatorial bonds of D
What is the class of flexible opioids?
Phenylpiperidine carboxylate class
When do flexible opioids have optimal activity?
methyl group on position 1 (N atom)
How are prodine and meperidine different structurally?
Prodine: contains methyl to C4 and reverse ester
Features of acyclic analgesic vs morphine
tolerance develops more slowly
less euphoria + less withdrawal
highly flexible
What is the best method of fragment based med chem?
NMR
Describe fragment based drug design
Find a lead fragment via NMR
Optimize fragment by adding groups to it to find what increases or decreases activity to discover new drug compopunds
How do we measure the probability of an effective drug compound?
using heavy atom count and free bond energy to calculate ligand efficiency (LE)
What is a pharmacophore?
Abstract description of molecular features of a compound
Why are pharmacophores used in drug discovery?
Used to show how structurally diverse compounds can bind to the same receptor/enzyme
- show minimum structure required for ligand receptor/enzyme recognition
What are the pharmacophore features of morphine like derivatives?
- hydrophobic region
- aromatic rings
- H donor/acceptors
- cations and anions
What does a 2D pharmacophore represent?
Minimum skeletal connecting important binding groups of the compounds
Does the 2D pharmacophore provide analgesic effects?
no!
requires stereochemical conformation with limited bond rotation
What does a 3D pharmacophore represent?
Define relative positions in space of the important binding groups
- gives opiates their analgesic activity