Agonist-to-Antagonist Spectrum of Action
Psychopharmacologic drugs work at the sites of neurotransmission and their effects are
based on a spectrum of agonist to an antagonist. An agonist is a molecule that is similar
...
Agonist-to-Antagonist Spectrum of Action
Psychopharmacologic drugs work at the sites of neurotransmission and their effects are
based on a spectrum of agonist to an antagonist. An agonist is a molecule that is similar to the
effects of a neurotransmitter by binding and stimulating the receptor site to produce a response
(Stahl, 2013). An antagonist opposes the outcome of the agonist, by blocking the action of
neurotransmission. Antagonists are known as the mediators of therapeutic actions in psychiatric
disorders and as the cause of undesirable side effects (Stahl, 2013). The spectrum of agonist to
antagonist consists of a full agonist, partial agonist, silent antagonist, and inverse agonists (Stahl,
2013). A full agonist allows the receptor to fully open the ion channel, which provides signal
transduction to occur. A partial agonist occurs when the receptor has a resting state. Next, on the
spectrum, the silent antagonist will return the receptor to a resting state. The last type on the
range is the inverse agonists which cause receptor change and the closing of ion channels.
Depending on where on where a particular psychopharmacological drug is on the agonist-toantagonist
spectrum, determines its interaction with the targeted receptor.
G Couple Proteins and Ion Gated Channels.
G couple proteins represent the most abundant family membrane proteins in the human
genome, which are activated by a spectrum of structurally diverse ligands (Kobilka, 2007). They
have seven different protein segments which span the membrane seven times and transmit
signals for binding sites for neurotransmitters (Stahl, 2013). This will allow for therapeutic drug
actions to occur. Once drugs attach to these receptor sites, a full or partial blocking function of
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