Explain the agonist-to-antagonist spectrum of action of
psychopharmacologic agents.
To understand the agonist-to-antagonist spectrum of action of
psychopharmacologic agents, it is first important to understand what does the terms
agonist and antagonist means. An agonist refers to a chemical that binds to a receptor,
the receptor activates and a biological response is produced. In comparison, an
antagonist blocks the action of agonist, and an inverse agonist causes an action opposite
to that of the agonist (Stahl, 2013). The agonist spectrum can be classified into four
types namely agonist, partial agonist, antagonist and inverse agonist (Stahl, 2013). The
agonist opens the channel the maximal amount and frequency allowed by the binding
site, while antagonist that lie in the middle of the spectrum retain the resting state with
infrequent opening of the channel. The inverse agonist put the ion channel into a closed
and inactive state. Antagonists holds the ability to block anything in the agonist
spectrum, and ions are returned to their resting state in each instance (Stahl, 2013). An
agonist tie to a receptor site and causes a response while an antagonist works against
the drug and blocks the receptor. An agonist stimulates the action, while antagonist sit
idle, doing nothing (Stahl, 2013). For ideal therapeutic action of a drug, ion flow and
signal transduction is required that is not too hot, neither too cold and has the right
balance. Such an ideal state varies from one clinical case to another and depends upon
the balance between agonism and silent antagonism (Stahl, 2013).

Compare and contrast the actions of g couple proteins and ion
gated channels.
Two broad families of receptor proteins perform their functioning in the opening
and closing of postsynaptic ion channels. The receptor in one family is called the
ionotropic receptor is linked directly to ion channels. These receptors have two functional
domains, the first one being an extracellular site that binds neurotransmitters, and the
second one being a membrane-spanning domain to form an ion channel (Purves, et al.,
2012). Therefore, inotropic receptors combine transmitter-binding and channel functions
into one single molecular entity and are called ligand-gated ion channels. Such receptors
are multimers and are comprised to four or five individual proteins subunit. Each of these
units play a part in pore of the ion channel (Purves, et al., 2012).
The second family of neurotransmitter is the metabotropic receptor. In this case,
the movement of ion depends upon one or more metabolic steps. In these receptors,
there are no ion channels, but channels are affected by the activation of intermediate
molecules called G-proteins. For this same reason, metabotropic receptors are also
referred to as G-protein-coupled receptors (Purves, et al., 2012). Metabotropic receptors
are monomeric proteins having an extracellular domain for neurotransmitter binding and
an intracellular domain for binding to G-proteins. Neurotransmitter binding to
metabotropic receptors activates G-proteins, after which it dissociates from the receptor
and interact directly with ion channels or bind to other effector proteins, like enzymes to
make intracellular messengers to open or close ion channels. Therefore, G-proteins work
as transducers that couple neurotransmitter binding to the regulation of postsynaptic ion
channels (Purves, et al., 2012).

Explain the role of epigenetics in pharmacologic action.
Epigenetics is the study of changes that influence the phenotype without causing
changes in the genotype. It is the study on heritable but reversible changes in gene
expression without any modifications of primary DNA sequence (Lundstorm, 2015).
Epigenetic mechanisms, especially circulating miRNAs have greatly in use today for
diagnostic biomarkers (Lundstorm, 2015). Epigenetic regulation of gene activity is
important in maintain normal phenotypic activity of cells, as well as in treatment of
disease such as cancer and neurodegenerative disorders such as dementia and
schizophrenia. New classes of drugs are currently used to regulate epigenetic
mechanisms to manage diseases in individuals (Stefanska & MacEwan, 2015).

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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
The understanding of pharmacology of drugs is important for psychiatric mental
health nurse practitioner as she must be aware how drug action would be beneficial for
the patient. The process involving medication prescription is especially critical for
psychiatric and mental health patients as alterations produced by neurocognitive
mechanism may lead to alteration of drugs (Angell & Bolden, 2015). Psychiatric mental
health nurse practitioner must be aware of medication?s action while working with
Alzheimer?s patients. Alzheimer?s disease is a chronic neurodegenerative disease that
usually starts slow and gets worse with the progressing time (Winblad, et al., 2016). The
disease cannot be treated completely but its worsening symptoms can be controlled.
Researchers and scientists are currently finding ways to find complete cure of the disease
through epigenetic modifications that can reverse the mechanism causing the
neurocognitive decline through pharmacologic agents (Cacabelos & Torrellas, 2014).
Therefore, knowledge about pharmacology of drugs is essential important for psychiatric
mental health nurse practitioner while treating patients suffering from Alzheimer disease
so she can determine whether the focus of treatment is on stopping the symptoms from
getting worse, or making an effort to reverse the disease process.

References
Angell, B., & Bolden, G. B. (2015). Justifying medication decisions in

mental health care: Psychiatrists? accounts for treatment
recommendations. Social Science & Medicine, 138(2), 44-56.

Cacabelos, R., & Torrellas, C. (2014). Epigenetic drug discovery for
Alzheimer’s disease. Expert Opinion on Drug Discovery, 9(9), 1059-
1086. doi:10.1517/17460441.2014.930124

Lundstorm, K. (2015). What is the potential of epigenetics in. Future
Medical Chemistry, 7(3), 239-242. doi:10.4155/FMC.15.2

Purves, D., Augustine, G., & Fitzpatrick, D. (2012). Neuroscience (5th
ed.). Sunderland (MA):: Sinauer Associates.

Stahl, S. M. (2013). Ion Channels as Targets of Psychopharmacologic
Drug Action. In Stahl?s essential psychopharmacology: Neuroscientific
basis and practical applications (3rd ed.). New York, NY: Cambridge
University Press.

Stefanska, B., & MacEwan, D. J. (2015). Epigenetics and
pharmacology. British Journal of Pharmacology, 172(11), 2701-2704.
doi:10.1111/bph.13136

Winblad, B., Amouyel, P., Andrieu, S., Ballard, C., Brayne, C., Brodaty,
H., & Fratiglioni, L. (2016). Defeating Alzheimer’s disease and
other dementias: A priority for European science and
society. The Lancet Neurology, 15(5), 455-532.

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REPLY QUOTE EMAIL AUTHOR

1 month ago

SHEILA BARTHELEMY

RE: Week 1
C OLL AP SE

Hi Julie,

Great description of agonist-to-antagonist. I agree with you that it?s very important to

understand the pharmacology of drugs for psychiatric patient, and the pharmacodynamic and

pharmacokinetic of drugs.Pharmacokinetics relates to what the body does with the drug that

is administered. It can determine absorption, dispersion and elimination rates in the body.

Pharmacodynamics is several processes by which medications can produce specific changes

in a person?s body (Arcangelo, et, al., 2017). There are several factors that come in to play

that affect pharmacokinetics and pharmacodynamics. Patients themselves can be a factor, as

every human being is different, depending on body type, height, weight, ethnicity and

genetics. Patient?s organ and tissues that are responsible for absorption and excretion also can

vary. Diet and nutrition play a large part in the metabolism of medications (Arcangelo et al.,

2017).

Reference

Arcangelo, V. P., Peterson, A. M., Wilbur, V., & Reinhold, J. A. (Eds.).

(2017). Pharmacotherapeutics for advanced practice: A

practical approach (4th ed.). Ambler, PA: Lippincott Williams &

Wilkins.

REPLY QUOTE

1 month ago

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Camille Markham

RE: Week 1 discussion Response One
C OLL AP SE

Week One Discussion: Response One

Camille Markham

Walden University

September 1, 2018

Hello Julie,

I enjoyed your post; you explained things so well that it broadened my understanding

of the subjects. Through our text and the additional readings I did for this forum, I learned

that there are several types of agonist. There are endogenous agonists which are naturally

present within the body and fully activate receptors. True to its name, a full agonist that is not

endogenous, yet, still fully activates a receptor. There is a superagonist which goes above

and beyond the activation caused by an endogenous agonist. The partial agonist at its best

effort cannot fully activate an agonist. The inverse agonist is not like an antagonist which

blocks the activation of an agonist. The inverse agonist causes the receptor to make an

opposite action. The most alarming to me is the irreversible agonist that makes an irreversible

activation of a receptor that destroys the receptor because it no longer can be activated (Aegis

Sciences Corporation, 2015).

I also learned that neuropsychiatric disorders are mainly disorders of cognition.

Cognitive manifestations of neuropsychiatric disorders include disturbances in the regulation

of attention, learning, impairments of memory and executive function. Neuropsychiatric

disorders affect the functionality and well-being of individuals and pose an economic burden

on families, communities, and society. Currently, treatment for mental disorders, both

psychologically and pharmacologically, targets the obvious symptoms of the diseases, but

rarely the cognitive impairments (except for some treatments for Alzheimer’s disease and

attention deficit hyperactivity disorder (ADHD)). These cognitive symptoms often persist

even after remission of the more acute symptoms of the illnesses like depression or

psychosis. Cognitive enhancing drugs are needed to improve the cognitive problems in

patients with neuropsychiatric disorders (Sahakian, 2015).

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I thought it interesting that the disease that you brought up in your initial post is one

of the conditions that is treated with pharmacological approaches that address the cognitive

impairments rather than the most apparent symptoms. I believe the nurse practitioner must

be acutely aware of the actions of each drug prescribed. When prescribing more than one

medication, it is essential to be sure that the actions of those work together potentiating each

other rather than working against each other or the chemical makeup of those for whom the

medications are prescribed. Don?t you?

References

Aegis Sciences Corporation. (2015). Pharmacology Corner: Agonists

and Antagonists. Retrieved from www.aegislabs.com: https:

https://www.aegislabs.com/agonists

Sahakian, B. B. (2015). The impact of neuroscience on society: cognitive

enhancement in neuropsychiatric disorders and in healthy

people. Philosophical Transactions of the Royal Society B:

Biological Sciences. doi:10.1098/rstb.2014.0214

REPLY QUOTE EMAIL AUTHOR

1 month ago

Todd Ludwig

Response 2
C OLL AP SE

Hi?Julie,
One?of?the?most?interesting?items?discovered?this?week?was?the?Cytochrome?P450?(CYP)?enzyme?

system?where?drug?metabolism?occurs?via?the?gastrointestinal?tract?and?the?liver?and?the?pharmacodynamic?
actions?such?as?therapeutic?effects?and?side?effects?of?psychotropic?drugs?can?be?altered?(Stahl,?2013).?I?visited?
one?of?my?patient?s?after?reviewing?this?specific?material.?She?has?a?diagnosis?of?bipolar?disorder,?anxiety,?
hyperlipidemia,?and?hypertension.?She?is?a?heavy?smoker?and?is?unable?to?sleep?and?remains?depressed?even?
with?a?prescribed?antidepressant.?Smoking?can?induce?the?enzyme?CYP?1A2?and?lower?the?concentration?of?
drugs?such?as?duloxetine?(substrate?of?1A2),?for?which?she?was?once?prescribed?(Stahl,?2013).?She?also?takes?
aripiprazole?(substrate?of?3A4),?fluoxetine?(inhibitor?of?2D6?and?3A4),?alprazolam?(substrate?of?3A4),?

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simvastatin?(substrate?of?3A4),?and?has?taken?Tylenol?with?codeine?(substrate?of?2D6),?and?ciprofloxacin?
(inhibitor?of?1A2)?(Stahl,?2013).?Taking?a?fresh,?new?look?at?her?past?and?current?medications,?I?begin?to?wonder
how?the?CYP?enzyme?system?was?affected?by?substrates?and?inhibitors?causing?the?patient?to?have?too?high?or?
too?low?plasma?levels?in?her?system.

Did?the?prescribed?duloxetine?not?work?for?this?patient?because?she?is?a?heavy?smoker;?is?she?receiving?
too?much?aripiprazole?with?the?potential?risk?for?increased?side?effects?such?as?tardive?dyskinesia,?tremors,?and?
muscle?spasms;?is?she?receiving?too?much?alprazolam?and?codeine?with?the?potential?risk?for?increased?side?
effects?such?as?sedation?and?falls;?and?is?she?receiving?too?much?simvastatin?with?the?potential?risk?for?increased?
muscle?damage??I?am?curious?if?most?physicians?and?ARNPs?consider?the?impact?specific?inhibitors?have?on?
CYP?enzymes?and?the?substrates?in?addition?to?the?plasma?levels?of?specific?substrates.?In?a?study?by?Radford,?
Fitzgerald,?Martin,?and?Johnson?(2016)?they?wanted?to?determine?The?aim?of?the?service?improvement?project?
was?to?determine?the?proportion?of?patients?referred?to?a?specialist?pain?service?in?the?UK?National?Health?
Service?(NHS)?by?general?practitioners?(GPs)?who?may?be?at?risk?of?suboptimal?analgesic?response?due?to?CYP?
2D6?inhibition?through?polypharmacy?(Radford?et?al.,?2016).?Their?finding?that?over?half?of?patients?had?been?
prescribed?at?least?one?analgesic?reliant?on?CYP2D6?is?of?concern?as?we?estimated?that?the?potential?risk?of?
clinically?significant?drug?interactions?to?be?19.9%?of?patients?and?suboptimal?analgesia?in?18.7%?of?patients?
(Radford?et?al.,?2016).?The?risk?of?Adverse?Drug?Reactions?(ADRs)?resulting?from?co?prescription?of?SSRIs,?
predominantly?sertraline,?citalopram,?and?fluoxetine,?was?of?particular?concern?with?6.25%?of?patients?at?risk?of?
serotonin?syndrome.?GPs?need?to?be?aware?that?the?risk?of?serotonin?syndrome?increases?with?the?co?prescription
of?SSRIs?with?tramadol?and?fentanyl?(Radford?et?al.,?2016).?There?was?also?the?risk?of?toxicity?from?
amitriptyline,?aripiprazole?and?clomipramine,?and?a?risk?of?suboptimal?response?to?the?CYP2D6?tamoxifen?
(Radford?et?al.,?2016).

Reference
Radford,?H.,?Fitagerald,?P.,?Martin,?S.,?&?Johnson,?M.?(2016).?A?service?improvement?

project?to?review?prescribing?information?provided?by?general?practitioners?for?
new?referrals?to?a?UK?National?Health?Service?hospital?pain?clinic:?potential?
implications?of?CYP2D6?enzyme?inhibition.?British Journal of Pain, 10(4),?
222?231.?Retrieved?from?https://eds?a?ebscohost?
com.ezp.waldenulibrary.org/eds/detail/detail?vid=2&sid=244d9ef3?1752?4ea8?
b64f?8e09db0d209d
%40sessionmgr4007&bdata=JnNpdGU9ZWRzLWxpdmUmc2NvcGU9c2l0ZQ
%3d%3d#AN=27867512&db=mnh

Stahl,?S.?M.?(2013).?Stahl?s essential psychopharmacology: Neuroscientific basis
and practical applications (4th?ed.).?New?York,?NY:?Cambridge?University?
Press?*Preface,?pp.?ix?x

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