A great example of a drug that acts as a partial agonist is cariprazine. Originally, cariprazine was approved to treat schizophrenia, both acute and maintenance, acute mania, and depression (Stahl et al., 2020). Cariprazine binds to D3 and D2 dopamines and several serotonin receptors with high and moderate potency (Stahl et al., 2020). In addition, the drug has a “moderate affinity for adrenergic, histaminergic, and cholinergic receptors” (Laszlovszky et al., 2021, p. 3654).
The essential aspect of cariprazine is its D3 preference, meaning that its binding affinity is higher for the D3 receptor compared to the D2 receptor (Stahl et al., 2020). Moreover, cariprazine’s binding affinity is higher than the D3 receptor’s dopamine affinity, so physiological doses of the drug construct a blockade of D3 receptors (Stahl et al., 2020). In other words, clinically relevant doses of cariprazine result in full occupancy of the D3 receptor (Laszlovszky et al., 2021). Everything described above represents the mechanism of action of cariprazine.
As mentioned earlier, cariprazine was initially approved to treat schizophrenia, mania, and depression. However, it has recently been approved for bipolar I depression (Stahl et al., 2020). Therefore, the pharmacological effects of the drug are actively explored in the current research. In general, cariprazine has antidepressant and procognitive effects (Stahl et al., 2020). The drug disinhibits the release of dopamine inside the prefrontal cortex, which promotes a positive dopamine tone (Stahl et al., 2020). When it comes to the side effects, the most common adverse reaction is extrapyramidal symptoms along with akathisia (Stahl et al., 2020).
However, cariprazine is better than other agents for sedation, weight gain, and prolactin elevation (Laszlovszky et al., 2021). Overall, cariprazine is an efficient partial agonist that has particular advantages compared to other similar drugs.
References
Laszlovszky, I., Barabássy, Á., & Németh, G. (2021). Cariprazine, a broad-spectrum antipsychotic for the treatment of schizophrenia: Pharmacology, efficacy, and safety. Advances in Therapy, 38, 3652-3673. Web.
Stahl, S. M., Laredo, S., & Morrissette, D. A. (2020). Cariprazine as a treatment across the bipolar I spectrum from depression to mania: Mechanism of action and review of clinical data. Therapeutic Advances in Psychopharmacology, 10, 1-11. Web.