This document discusses the spectrum of action of psychopharmacological agents from full agonists to antagonists to inverse agonists and how this impacts treatment efficacy. It explains that agonists activate receptors to produce a response while antagonists bind to receptors but do not produce a response. Partial and inverse agonists can produce submaximal or opposite responses compared to full agonists. The role of epigenetics in pharmacology is also discussed, noting how environmental and behavioral factors can influence gene expression and drug responses without changing DNA. This information is important for psychiatric nurse practitioners to consider individual patient factors, like genetics and medications, when prescribing to optimize outcomes.

1. 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.
An agonist is a drug that binds to the receptor and
generates a required or full response to the intended chemical
and receptor in the brain but an antagonist is a drug that binds
to the receptor and hinders the receptor from producing a
response. This is important to enable drugs to produce the
required effect that is individualized for each patient. Agonists
cause an action and antagonist opposes the action. Agonists are
drugs with both affinity and inherent efficacy. In other words,
agonists attach to the target receptor and can modify the
receptor activity to generate a response. Antagonists on the
other hand have affinity but no inherent efficacy; hence they
can stick to the target receptor and do not generate any
response. Antagonist generally minimizes the probability of
occupancy by an agonist by virtue of occupying a portion of the
receptor population.
Agonists can have various inherent efficacies and thus
can be described as full or partial agonists based on the drug
framework (Berg & Clarke 2018). A full agonist according to
Berg & Clarke study, generates the full response a system is
made for while a partial agonist generates a submaximal
response. Also, an Inverse agonist is a drug that binds to the
same receptor as an agonist but induces an opposite
pharmacological response to that of the agonist. This means
that its effect on the target cell is inconsistent with that of the
agonist.
For example, the pharmacological management for the recovery

2. from opioid use disorder includes the opioid agonist or
antagonist therapy. Full agonist opioids activate the opioid
receptors in the brain giving rise to the full opioid effect while
the antagonist blocks opioids by attaching to the opioid
receptors and causing no opioid effect ( US Department of
health and Human services, n.d).
Compare and contrast the actions of g couple proteins and ion
gated channels
Appropriate neurotransmission needs precise interplay
of so many neurotransmitter receptors at pre- and post-synaptic
compartments. Transmission at most mammalian synapses
requires neurotransmitter activation of two receptor subtypes, G
protein-coupled receptors (GPCRs) and ligand-gated ion
channels (Johnson & Lovinger, 2016). G protein–coupled
receptors (GPCRs) mediate most cellular responses to external
stimuli, such as light, odors, hormones, and growth factors.
They interfere with the sense of vision, smell, taste, and pain
and are involved in cell recognition and communication. Ion
channels aid ion influx across the membrane and is the
foundation of electrical excitation of neurons ( Li etal., 2014).
Ion channel receptors are essential in the nervous system,
allowing for signaling, fast and direct conversion of a chemical
neurotransmitter message to an electrical current.
While the ligand-gated ion channels can moderate fast
synaptic responses, the G protein-coupled receptors (GPCRs)
have slower neuromodulatory actions. The GPCRs constitute a
large portion of neurotransmitter receptors needed in virtually
all phases of the nervous system function and are also targets
for majority of pharmacotherapeutic agents. Ion channel -linked
receptors open a channel in the membrane enabling the passage
of ions while G-protein-linked receptors activates a membrane
protein known as G-protein, which helps to interact with an
ion channel or an enzyme in the membrane.

3. Explain how the role of epigenetics may contribute to
pharmacologic action
Epigenetics is the study of how an individual’s
behaviors and environment can result in changes that affect the
functioning of genes (Centers for Disease Control and
Prevention, 2020). Epigenetic changes can be reversed., they do
not change the DNA sequence, but rather can change the way
the body reads a DNA sequence. Epigenetic regulation of gene
activity is shown to be involved in the evolution of diseases
such as cancer and neurodegenerative disorders like
Alzheimer's. Recent classification of drugs regulates epigenetic
mechanisms to counteract disease found in human beings
(Stefanska & MacEwan, 2015). Personalized medicines are
given to patients after collecting genomic information such as
the levels of RNA, proteins and metabolites that could aid
medical decision making.
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.
The impact this information will have on my ability to
prescribe medications is raising my concern for patient’s safety
and need for critical thinking. This will create the awareness
that each prescription should be individualized based on each
patient’s presenting symptoms, overall goal of treatment and
long-term effect of the medication. Knowing the
pharmacokinetics, pharmacodynamics is essential in
determining which drug should be prescribed for each patient.
Pharmacogenomics provides understanding of the actual drug
for each patient at the exact concentration and time. With the
concern of multiple drug responses, factors including nutrition,

4. age, body weight, sex, genetic behavior, infections, co-
medications, and organ function are relevant to be considered
with treatment of a disease and the ideal medication that should
be prescribed.
For example, in the management of Alzheimer’s
disease, using donepezil (Acetylcholinesterase inhibitors), it is
important to educate the patient and family that gastrointestinal
problems could be side effects from the medication. This could
aid adherence to the medication with reduced abrupt
discontinuation. Also, donepezil can lead to side effects such as
seizures, bradycardia, and heart block, therefore reviewing each
patient’s medical history and determining the best medication
that is patient centered is essential to promote health and
achieve positive outcomes from medications. Donepezil and
other cholinomimetic agents can cause seizures; therefore
healthcare professionals should be cautious in prescribing this
medication in individuals with a history of seizure disorder (
Kumar & Sharma, 2020).
References
Centers for Disease Control and Prevention. (2020). Genomics
& Precision Health.
https://www.cdc.gov/genomics/disease/epigenetics.htm
Kumar, A., Sharma, S. (2020). Donepezil. StatPearls.
https://www.ncbi.nlm.nih.gov/books/NBK513257/
Li, S., Wong, A., Liu, F. (2014). Ligand-gated ion channel
interacting proteins and their role in neuroprotection. Frontiers
in Cellular Neuroscience, 8 (125). doi:
10.3389/fncel.2014.00125.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4023026/
Stefanska, B., MacEwan, D. (2015). Epigenetics and

5. pharmacology.
British Journal of Pharmacology, 172
(11), 2701-2704. doi: 10.1111/bph.13136.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4439868/
US Department of health and Human services. (n.d).
Pharmacological treatment. Indian Health Service.
https://www.ihs.gov/opioids/recovery/pharmatreatment/