The Psychiatric Mental Health Nurse Practitioner (PMHNP) will have to prescribe psychotropic drugs when treating the client with mental health disorders or even for chemical dependency. The clinician must be knowledgeable about how these medications work so that safe and effective treatment can be given to the client. According to Stahl (2013), thirty percent of psychotropic drugs impact the G-protein linked cascade, and twenty percent of psychotropic drugs target the ligand-gated ion channel. Understanding these systems give the practitioner clarity on how these drugs can be useful.
Agonist to Antagonist Spectrum
Receptors are specialized proteins found in the cells or on the surface of neurons. (Nutt et al., 2007). Post-synaptic receptors generally regulate the actions of the released neurotransmitter (Nutt et al., 2007). Drugs may be referred to as agonists, partial agonists, antagonists, or inverse agonists, which means that they affect the level of neurotransmission at the post-synaptic neuron (Stahl, 2013). An agonist imitates the action of endogenous neurotransmitters. Agonists may directly bind to the neurotransmitter site (which may cause a change in the shape of the receptor) or may indirectly cause an increase in the level of neurotransmitters released. A partial agonist also causes an increase in neurotransmission effects but does not have as high and effect as a full agonist would. An antagonist, on the other hand, may either block normal neurotransmission or cause a reversal in the shape of the receptor so that the effects are opposite to the agonist (Stahl, 2013). For example, in schizophrenia, it is believed that overactive or high levels of dopamine contribute to the illness; hence a D2 antagonist (such as Haldol) may be given to inhibit dopamine release (Guzman, 2019). An agonist will increase neurotransmitter signals or levels by a significant amount; partial agonist with also increase levels but not to the extent of the full agonist, while an antagonist will inhibit signals or reverse what an agonist has done.
G couple proteins and Ion Gated channels
As stated earlier, G couple proteins and Ion gated channels are molecular targets for psychotropic drugs. Both G couple proteins and Ion- gated channels are activated by neurotransmitters which then activate genes in the cell nucleus (Stahl, 2013). G couple protein works have a cascade involving cAMP (cyclic adenosine monophosphate) and protein kinase A. On the other hand, the ion gated channel works through calcium, and it activates different kinase called calcium-dependent protein kinase (Stahl, 2013). Both systems affect gene expression; however they do so at via separate systems.
Neurotransmission seeks to modify the cell function of gene expression, meaning, turning some genes on and others off. When the cell nucleus changes, it is because the structure of chromatin is modified; hence, gene expression is modified. Epigenetics speaks to changes in the genes that lead to long term changes in how the gene is expressed. This is important in pharmacology as some illnesses such as cancer may have several mutations and, as such, may be challenging to treat (Stefanksa and MacEwan, 2015). However, if the changes in the genes that lead to cancer are studied, then drugs that target those genetic changes can be developed, hence, solving the root of the problem rather than trying to eradicate cancer. Simply put, change gene expression so that it does not lead to cancer (Stefanksa and Mac Ewan, 2015).
How It Impacts the Way Medications are Prescribed
As previously mentioned, prescribers/ clinicians need to know this information for safe, effective, and efficient treatment. Understanding the neuroscience can reduce prescriber error. Stahl (2013) discusses the fact that twenty percent of Asians are poor metabolizers of the Cytochrome CYP 2C19. Hence, the practitioner needs to know that psychotropic drugs metabolized by this enzyme need to be closely monitored as the drug can quickly build up in the patient’s bloodstream. Watching dosing strengths, as well as other medications that may further inhibit this enzyme, could cause an increase in drug levels in the body.
Andrade, C., & Sathyanarayana Rao, T. (2016, June). Classification of psychotropic drugs: Problems, solutions, and more problems. Indian Journal of Psychiatry, 58(2), 111-113. doi:10.4103/0019-5545.183771
Guzman, F. (2019, June 27). First-Generation Antipsychotics: An Introduction. In Psychopharmacology Institute. Retrieved from https://psychopharmacologyinstitute.com/publication/first-generation-antipsychotics-an-introduction-2110?canonical=/publication/first-generation-antipsychotics-an-introduction-2110
Guzman, F. (2019, June 27). D2 Receptors in Psychopharmacology. In Psychopharmacology Institute. Retrieved from https://psychopharmacologyinstitute.com/publication/d2-receptors-in-psychopharmacology-2116
Nutt, D., & Lingford-Hughes, A. Key concepts in Psychopharmacology. Psychiatry, 263-267. doi: 10.1016/j.mppsy.2007.05.00