Explain the agonist-to-antagonist spectrum of action of psychopharmacologic agents, including how partial and inverse agonist functionality may impact the efficacy of psychopharmacologic treatments.
Neurotransmitters and some drugs that stimulate receptors are called agonists. Agonists stimulate receptors to their fullest signal transduction. Drugs that act as agonists are useful in patients who lack or are deficient in agonist neurotransmitters. In situations where the actions of a full agonist or partial agonists are undesirable, an antagonist is required to revert the receptor back to the state where no agonist exists, back to neutral. Partial agonists act as they sound, and produce a conformational change of a receptor that is halfway between the changes of a full agonist and the baseline conformation of that receptor. An antagonist can also reverse the effects of inverse agonists to the receptors baseline. An inverse agonist acts to change the conformation of a receptor to completely inactivate it and remove the baseline constitutive activity.
Compare and contrast the actions of g coupled proteins and ion gated channels.
Both G protein coupled receptors and Ion gated channels are a form of signal transduction cascades in the brain. They are both triggered by neurotransmitters, and many of the psychotropic drugs used today affect one of these two cascades. They both perform when an extracellular first messenger passes a message to an intracellular second messenger. However, G protein’s second messenger is a chemical, such as adenosine monophosphate, while the ion channel second messenger can be an ion, such as calcium. There are two classes of ion channels, Ligand gated and voltage sensitive ion channels. The ligand gated ion channels act similar to g protein receptors because they use the agonist spectrum. Voltage sensitive ion channels are opened and closed based on the voltage charge across the membrane.
Explain how the role of epigenetics may contribute to pharmacologic action.
Epigenetics determines if inherited genes are expressed or not expressed into proteins that make up the story of any one person. The mechanism of epigenetics turns genes on or off by modifying chromatin. These modifications are regulated by neurotransmitters, drugs and the environment. So drugs introduced to patients can affect a person’s epigenetics.
Explain how this information may impact the way you prescribe medications to patients. Include a specific example of a situation or case with a patient in which the psychiatric mental health nurse practitioner must be aware of the medication’s action.
Understanding the way medications will affect patients based on their genetic makeup, their current medications, the condition being treated, what causes the imbalance, is all important when prescribing medications. For example imipramine, a tricyclic antidepressant, inhibits the reuptake of serotonin and norepinephrine, elevating these neurotransmitters in the brain. It is important to understand if this is the cause of the patients depression before prescribing this medication because if incorrectly prescribed it could alter the patients epigenetic mechanisms in an inverse way (Boks, et al. 2012).