Phase 1 and Phase 2 Rxns and pharmacogenomics Flashcards
(34 cards)
Phase 1 rxns
focused on adding or unmasking polar groups such as (OH, NH2) If a molecule has a methoxyl group, it will remove it leaving the hydroxyl.
P1 rxns can either be
oxidation or Hydrolysis reduction
P1 rxns will generate products that are either
electrophiles or nucleophiles
For a phase 2 reaction, the nucleophiles generated from phase 1 reaction will undergo
sulfonation
acetylation
glucuronidation
For a phase 2 reaction, the electrophiles generated from phase 1 reaction will undergo
Glutathione conjugation
Cytoplasm is a - environment
Reducing
Exception to P1—>P2
Ionizide undergoes acetylation and then hydrolysis
Ethanol and nicotine usually
speed up the metabolism of other drugs
Ethanol is given for methanol poisoning, why?
Ethanol induces stimulation of liver enzymes in order to get rid and metabolize the methanol.
Molecule in grapefruit juice
furanocoumarin
Tylenol can undergo
Glucuronidation or sulfonation
A class of enzymes known as ? will ? Tylenol.
Monooxygenase hydroxylation. This will oxidize Tylenol. And can be a harmful electrophile.
Molecule given for Tylenol overdose
N-Acetylcysteine – This has a very potent sulfhydryl group to react with the potent electrophile. Must be given early so that it does not interact with other molecules.
How to smartly use drug metabolizing enzymes and issues that may arise.
First pass effect may result in the molecules becoming inactive. Design a molecule that will be activated as metabolism goes on.
Tamoxifen is used to treat breast cancer , tamoxifen is a
prodrug, and endoxifen is the pharmacologically active drug.
This is a highly polymorphic cytochrome
CYP2D6
Codeine is a prodrug used an an analgensic, broken down by
CYP2D6
- Ultrarapid
- Extensive
- Intermediate metabolizer
- Poor metabolizer
- more than two copies of functional allele
- two functional alleles
- one reduced and one nonfunctional
- no functional alleles
Hawaii lawsuit enzyme and drug
Clopidogrel and CYP2C19 (<15%)
Clopidogrel and SR26334 (> 85%)
Used in treatment of colorectal cancer
Fluorouracil -Enzyme is DPD-Dihydropyrimidine Dehydrogenase
Example of using first pass effect to advantage
Loratadine metabolized to Descarboethoxyloratadine
More alpha-2 receptors means
more likely to develop nicotine addiction
Four focuses on drug metabolism
- Genetic variations in enzymes
- ” “ “”” transporters
- ””””” immune system function
- polygenic effects
Codeine is
lipophilic and can cause opioids to pass through the breast milk and target breathing center of the brain.