Lecture 2 Flashcards
What is an Antagonist?
-Binds the receptor and blocks the effect
What would happen if Morphine is administered with an antagonist?
The curve will shift to the right -> indicating that a higher dose is needed to achieve 100% efficacy
-the more of the antagonist is added the higher dose of morphine is needed to achieve 100% (more shifted to the right)
How can morphine overcome the effects of a competitive antagonist?
-By increasing the dose of morphine to swap out the antagonist (Naloxone) -> morphine and naloxone compete for the same receptor!
Why can drugs be swapped out of its receptor?
Because certain drugs bind to their receptor through weak bonds
Do Antagonist have any effect when given alone?
No
What is the function of alpha-adrenergic drugs?
increase blood pressure
-> Phenylephrine (OTC decongestant, also raises BP)
What would happen if an alpha adrenic drug is administered with a non-competitive antagonist?
Phenylephrine with Phenoxybenzamine
-there will be a shift to the right -> more dose is needed to reach 100% efficacy
-as we increase the dose of the antagonist there will be a shift to the right + decrease in efficacy
-non-competitive antagonists bind covalently to the receptor (until the receptor is degraded) -> it cant be outcompeted by an increase of the drug dose
What are spare receptors?
-indicates that not all receptors are needed to reach 100% efficacy
-some organ systems have more, and some have fewer space receptors
-f.e. in Parkinsons disease, no evidence is seen until 70% of receptors are destroyed
What are uncompetitive Antagonists?
-something away from the receptor has to happen before the receptor works
-f.e. Mg needs to bind to an ion channel before the channel opens, blocking the Mg binding site will prevent the drug from working -> ALLOSTERIC effect
What do partial agonists and non-competitive Antagonists have in common?
They reduce efficacy+ of a drug
When should drugs against withdrawal symptoms be administered?
-when they are experiencing withdrawal symptoms, rather than when they are high (it will reduce the highness)
An example where partial agonists are used?
Treat withdrawal symptoms (vomiting, nausea, pain)
-the efficacy is reduced compared to the addictive drug -> but still high enough to treat the symptoms
Example: Morphine + Diprenorphine (partial Agonist)
Phenylephrine + Phenoxybenzamine (non-competitive Antagonist)?
What happens if Diprenophine (partial agonist) + Naloxone are given sublingually and Naloxone is swallowed?
Naloxone is supposed to counteract Diprenorphine, but is less lipid soluble -> it won’t get absorbed so much sublingually and is getting swallowed and undergoes first-pass metabolism -> so it won’t work against morphine
What happens if Naloxone (Antagonist) + Diprenorphine (partial agonist - makes high) are taken intravenously (drug abuse)?
No effect because Naloxone will block the receptors as an Antagonist
Why does Suboxone have Naloxone in it?
