How does the process of receptor blocking impact the human cells in context of antihistamine drugs (irreversible antagonist)?
I have problem in understanding what it really means that antagonist is irreversible.
I have an allergy and I stopped to take some drugs because of side effects.
I tried to predict how long does it take to go to the same state as before taking drugs.
I learned about biological half-life of medicines so I could predict how long it will take for drug to stop being active.
But then I read that my antihistamine drug is an irreversible antagonist.
I’ve checked the definition, and if I understand it, this means that the receptors are permanently blocked through some reaction with this antagonist.
The question is:
Does it mean that this cell which receptors are blocked is defective forever?
And side effects will never go away because, in this case, cell needs histamine to work properly?
Or we must wait for the cell to die and be replaced by new cell?
Sorry if my questions are not on appropriate level.
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It means that the receptors are blocked forever. A cell is a living thing, continuously producing new proteins (including receptors) and recycling old ones. So the cell is not defective forever, it will slowly phase out its blocked receptors and replace them with new ones.
You can read the basics of the way receptors work in textbooks on cell signalling, such as www.amazon.com/Cellular-Signal-Processing-Introduction-Transduction/dp/0815342152/. A topic of special interest would be ubiquitination, en.wikipedia.org/wiki/Ubiquitin#Ubiquitination.
I’ve found a quotation that sheds some light on the topic:
The rate of termination of the action of a reversible
antagonist is largely dependent on the half-life of the
drug as well as the rate at which it dissociates from its
receptor: the shorter the half-life, the less time it takes
until the effects of the drug are dissipated. However, the
effects of an irreversible antagonist may persist long after
the drug has been cleared from the plasma. In the case of
phenoxybenzamine, the restoration of tissue responsive-
ness after extensive ?-receptor blockade is dependent on
synthesis of new receptors, which may take several days.
(Peter D. Bryson: Comprehensive Reviews in Toxicology: For Emergency Clinicians)
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