Explain the agonist-to-antagonist spectrum of action of psychopharmacologic agents.
Agonists modulate the extent and frequency of opening up of ion channels at receptor sites, thus facilitating the downstream signal transduction at the binding site of the pharmacological agent. Full agonists, therefore, increase the extent and frequency of opening of the ion channels, consequently allowing maximum signal transduction at the binding site. Antagonists, on the other hand, cause stability of the receptor sites during the resting phase. They also exhibit the stabilizing effect in the absence of the agonist, which is regarded as the same mechanism of action in an extended resting phase (Stahl, 2013).
Compare and contrast the actions of G-coupled proteins and ion gated channels.
The structural features of G-coupled proteins involve seven transmembrane proteins that span the membrane seven times around a central core. The central core in each membrane contains a binding site for a neurotransmitter where drug interactions occur. Drug interactions can also occur at allosteric sites within the receptor. Binding of drugs causes alterations of the G-protein linked receptor, which are manifested through the exacerbation or amelioration of the psychiatric disorders and symptoms. The structure of ion-gated channels comprises of long chains of amino acids clustered as subunits around an ion channel. The receptors and binding sites of ions, neurotransmitters, and drugs occur around the subunits. The nature of the protein or ion influences the sensitivity and extent of the opening of the channel (Stahl, 2013).
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Explain the role of epigenetics in pharmacologic action.
Epigenetics explains whether a certain DNA code is transcribed into a specific RNA and protein or it is silenced. The silencing or expression of certain genes determines the occurrence of abnormal functioning neurons, which are the precursors of psychiatric diagnosis. Epigenetic modifications such as de-acetylation and histone modifications result in changes in gene expression and consequently modulates the drug target and receptors (Stahl, 2013). Thus, the pharmacologic action of psychiatric drugs is greatly influenced by the transcription and expression of the defective neurons.
Explain how this information may impact the way you prescribe medications to clients. Include a specific example of a situation or case with a client in which the psychiatric mental health nurse practitioner must be aware of the medication’s action.
Knowledge on the pharmacology, pharmacodynamics, and pharmacokinetics of the drug are imperative in the prescription of drugs. The individual’s genetic predisposition is also important in influencing the drug’s action and consequently, the choice and prescription of the drug. The underlying biological mechanisms of mental illness involves understanding the social processes, modulatory, cognitive, positive and negative valence systems. It is also important to link the patient’s behavior with the biologic and physiologic symptoms manifested (Laureate Education, 2016) . A client with anxiety disorders will need to be prescribed with selective serotonin reuptake inhibitors (SSRI) such as citalopram and sertraline. In this case, it is important to evaluate the extent of the client’s genetic predispositions and extent of the symptoms based on their behavior. This will be significant in determining the appropriate dosage (Stahl, 2017). Given that the client has anxiety disorders, patient education is vital, to inform them that they will not “feel better” immediately until a certain therapeutic level is attained.
References
Laureate Education (Producer). (2016). Pathopharmacology: Disorders of the nervous system: Exploring the human brain [Video file]. Baltimore, MD: Author.
Stahl, S. M. (2013). Stahl’s essential psychopharmacology: Neuroscientific basis and practical applications (4th Ed.). New York, NY: Cambridge University Press.
Stahl, S. M. (2017). Prescriber's Guide: Stahl's Essential Psychopharmacology . Cambridge University Press.
