Which of the follow does NOT act as a monoamine agonist?
A butyrophenone antipsychotics
B SSRIs
C tricyclics SNRIS
The correct answer and explanation is:
The correct answer is A butyrophenone antipsychotics.
Explanation:
Monoamine agonists are substances that stimulate or enhance the activity of neurotransmitters like serotonin, norepinephrine, and dopamine. These neurotransmitters play a key role in mood regulation, cognition, and other brain functions.
- SSRIs (Selective Serotonin Reuptake Inhibitors): These drugs, like fluoxetine (Prozac) and sertraline (Zoloft), act by inhibiting the reuptake of serotonin in the brain. This increases the availability of serotonin at synaptic sites, enhancing its effect. Therefore, SSRIs are considered serotonergic and act as monoamine agonists by increasing serotonin levels.
- Tricyclic Antidepressants (TCAs) and SNRIs (Serotonin-Norepinephrine Reuptake Inhibitors): Both TCAs (such as amitriptyline) and SNRIs (like venlafaxine) work by blocking the reuptake of serotonin and norepinephrine. TCAs also affect histamine and acetylcholine, while SNRIs specifically target serotonin and norepinephrine. This increases the levels of these neurotransmitters, making them monoamine agonists as well.
- Butyrophenone Antipsychotics: These drugs, such as haloperidol, are used primarily as antipsychotic agents. Butyrophenones act as dopamine antagonists, meaning they block dopamine receptors rather than enhancing dopamine activity. While they affect the dopaminergic system, they do so by reducing dopamine activity rather than increasing it. This makes them not a monoamine agonist.
Thus, the butyrophenone antipsychotics do not act as monoamine agonists because they inhibit dopamine’s action rather than stimulate the action of neurotransmitters.