Journal of Psychosocial Nursing and Mental Health Services

Psychopharmacology 

Physiological Measurements for Prescribing Psychotropic Medications

Barbara J. Limandri, PhD, PMHNP, BC

Abstract

Prescribing for individuals with mental health problems requires a thorough initial assessment that includes extensive interviewing of the client and significant others, review of medical records, and physical appraisals, such as vital signs, laboratory tests, and electrocardiography. Arriving at a diagnosis and treatment plan includes ruling out comorbid conditions as well as medical conditions that mimic psychiatric disorders. Because substance use frequently coincides with other psychiatric disorders and has serious health consequences, this potential for misuse of substances must also be considered. The current article focuses on the physiological assessments necessary for prescribing and monitoring psychotropic medications. [Journal of Psychosocial Nursing and Mental Health Services, 57(8), 7–10.]

Abstract

Prescribing for individuals with mental health problems requires a thorough initial assessment that includes extensive interviewing of the client and significant others, review of medical records, and physical appraisals, such as vital signs, laboratory tests, and electrocardiography. Arriving at a diagnosis and treatment plan includes ruling out comorbid conditions as well as medical conditions that mimic psychiatric disorders. Because substance use frequently coincides with other psychiatric disorders and has serious health consequences, this potential for misuse of substances must also be considered. The current article focuses on the physiological assessments necessary for prescribing and monitoring psychotropic medications. [Journal of Psychosocial Nursing and Mental Health Services, 57(8), 7–10.]

Exploring psychotherapeutic issues and agents in clinical practice

Prescribing within the advanced practice psychiatric nurse (APPN) role requires extensive data collection to make thoughtful clinical decisions, including diagnosis, treatment planning, and medication management. Data collection begins with extensive interviewing and use of screening and detailed assessment tools to arrive at diagnoses as well as reviewing medical records, conducting a basic physical examination, and seeking basic laboratory and other diagnostic testing to clarify physical conditions that mimic or complicate psychiatric symptoms. The current article focuses on the physiological measurements that help determine what medications would be most effective and how to monitor for adverse effects and comorbid conditions.

Baseline Assessments

In the initial assessment of a new client, certain baseline laboratory tests help clarify the client's overall health state and rule out possible contributory health problems to clarify symptoms and response to medications. In addition, because substance use frequently accompanies other psychiatric conditions, it is important to rule out concomitant use and health consequences of substance use. The basic starting point is vital signs, including pulse, blood pressure, and measurement of (not simply client report) height, weight, and waist circumference to determine body mass index. When interviewing the client initially, the APPN concludes the in-take session with an explanation of why it is important to assess the client's overall health state with laboratory tests and reserve prescribing any medications until receipt of test results.

Table 1 shows the screening tests recommended for the initial assessment. Because laboratory normal values vary slightly, it is important to review laboratory results using the reference values of the particular laboratory facility. The ICD-10-CM diagnosis code for laboratory screening is Z13.30 (ICD10Data.com, 2019) and is usually covered by Medicare, Medicaid, and third-party payors.

Diagnostic Tests for Initial Psychiatric Assessment

Table 1:

Diagnostic Tests for Initial Psychiatric Assessment

Assessments for Comorbidity

In addition to psychiatric disorders, the initial psychiatric assessment must consider possible comorbid conditions that may explain or exacerbate the client's symptoms. The most common causes of mortality in individuals with mental illness are stroke, hypertension, diabetes, ischemic heart disease, and chronic obstructive pulmonary disease (Filipcic et al., 2018), which are associated with tobacco and alcohol use (Basu, Basu, & Ghosh, 2018). Substance use disorders and other medical conditions influence clinical outcomes as well as affect medication interactions. When substance use disorders are part of the overall diagnostic picture, it is important to include gamma-glutamyl transferase and serum glutamic oxaloacetic transaminase in liver function tests as well as amylase and lipase levels. HIV testing may also be necessary as well as a full hepatitis A, B, and C panel to rule out infections associated with needle use (Basu et al., 2018; Rosse & Deutsch, 2004). Vital signs, such as blood pressure, weight, and waist circumference, are also important indicators of comorbid medical conditions.

Medication-Specific Monitoring

After initial assessment, follow-up assessments are specific to the medications prescribed. Pharmacogenomic testing of the cytochrome p 450 system is useful in determining potential adverse responses to medications related to a client's ability to metabolize medications; however, the cost outweighs the benefits in terms of usefulness of the information for prescribing. Pharmacogenomic testing serves best when a client fails to respond to more than one class of medication after assurance of dosage consistency and adequate trial period (Limandri, 2019; Narang, Johnson, Enja, & Lippmann, 2016).

Serum Levels

Typically, clients do not take their medications as prescribed, and rates of medication adherence among individuals with mental disorders range from 35% to 60% (Semahegn et al., 2018). Nonadherence may be as simple as forgetting to take one or two doses per week to not refilling a prescription, to never picking up a new prescription. Yet, clients may list their prescribed medications in a visit without clarifying how they actually take them. To clarify client response to medication adherence, it is essential to assure that the client is taking the medication in a manner that will provide a response. Determining medication adherence can best be achieved by obtaining serum levels of the medication after reaching steady state (i.e., five times the half-life of the drug). There are established therapeutic ranges for lithium, valproic acid, carbamazepine, clozapine, and tricyclic and monoamine inhibitor antidepressants; however, it is also possible to obtain plasma levels of serotonin and norepinephrine reuptake inhibitors (Brown University, 2011; Miller, 2014). Because some drugs (e.g., fluoxetine) have active metabolites, it is important to review prodrug levels and active metabolites to evaluate the therapeutic level. When ordering serum drug levels, the APPN needs to advise the client to have the labs drawn before the morning dose for a trough level. Cigarette smoking and caffeine consumption may affect drug metabolism; therefore, the concentration of the drug may change when the client alters his/her smoking or caffeine consumption (Oliveira, Ribeiro, Donato, & Madeira, 2017).

Antipsychotic Medications

Because dopamine antagonists (i.e., first-generation antipsychotics) and serotonin dopamine antagonists (i.e., second-generation antipsychotics) have different adverse effects, it is necessary to closely monitor serum levels and metabolic parameters. Dopamine antagonists have more significant extrapyramidal effects, best monitored by the Abnormal Involuntary Movements Scale and physical observation. However, dopamine antagonists and serotonin dopamine antagonists have serious metabolic consequences that need to be specifically monitored regularly. The easiest and most direct measurement of metabolic effects is weight and waist circumference (taken at the umbilicus) on a monthly basis (Mustafa et al., 2018; Nicol et al., 2019). In addition, monitoring the serum lipid panel, hemoglobin A1c, and fasting glucose on a semi-annual basis is warranted for prevention of metabolic syndrome and diabetes (Miller, 2014). Medication-induced hyperprolactinemia occurs in several dopamine antagonists (e.g., risperidone) and serotonin dopamine antagonists (e.g., aripiprazole, clozapine, olanzapine, quetiapine, ziprasidone); therefore, serum prolactin levels need to be monitored on a semi-annual basis initially then annually (Kirino, 2017). With clozapine, it is also essential to monitor white blood count with absolute neutrophil count on a weekly basis for the first 6 months, then every 2 weeks for 6 months, then monthly if the values are within normal limits (Myles et al., 2019; Verdoux, Quiles, Bachmann, & Siskind, 2018).

Mood Modulators

Lithium monitoring requires serum drug levels on a monthly basis until therapeutic level is achieved then semi-annually as clinically indicated. In addition, thyroid function needs to be monitored within 1 month of initiation and annually thereafter, as well as renal function. Valproic acid and carbamazepine require serum drug levels the first month of initiation then annually or as clinically indicated, as well as complete blood cell and platelet counts, and lamotrigine requires serum drug levels the first month of initiation and then annually as clinically indicated (Wheeler, Robinson, & Fraser, 2008).

Antidepressant Medications

Although therapeutic drug monitoring is usually only performed with tricyclic and monoamine inhibitors, it is reasonable to monitor all antidepressant serum levels on an annual basis or if clinical response is ineffective to assure dose adherence and metabolism. In addition, many serotonin reuptake inhibitors affect bone density and contribute to fractures, especially in older clients (Bolton et al., 2017; Zhou et al., 2018); therefore, annual bone density is recommended in these clients. Serotonin reuptake inhibitors and serotonin norepinephrine reuptake inhibitors affect lipid levels and contribute to weight gain as well as antipsychotics, thus monthly weight and girth measurements are recommended as well as annual lipid panels (Hasnain & Vieweg, 2013; Noordam et al., 2015).

Summary and Conclusion

Diagnostic measurements, such as laboratory tests, electrocardiography, electroencephalography, and radiography, are necessary tools in the initial assessment of clients and for monitoring outcomes of treatment. Informing clients of the benefits in overall health and specific mental health treatment is crucial for their relationship with psychiatric nurses. Thorough assessment connotes holistic caring as well as responsible client advocacy and treatment standards. When abnormalities are discovered, the APPN documents the results and clinical decision making in the client record and refers the client to appropriate follow up with specialists or the primary care provider. Continued collaboration with other health providers maintains continuity of care.

For APPNs, general principles of assessment to incorporate into practice include (Janicak, Marder, & Pavuluri, 2011) the following.

  • Begin with a general physical examination specific to the client's presenting problems, including vital signs, weight, and basic neurological examination.
  • Avoid wasteful screening batteries with limited clinical use.
  • Recognize signs and symptoms that indicate need for further evaluation or referral to another health care provider.
  • Use treatment options that can be supported by specific laboratory tests (e.g., serum level).
  • Monitor clinical outcomes at standardized frequencies or as clinically indicated by client response.
  • Explain the need for laboratory assessment to the client at the outset and need for periodic monitoring.
  • Elicit client's consent and follow through with periodic testing as necessary for continued prescribing.

References

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Diagnostic Tests for Initial Psychiatric Assessment

TestComponents and Purpose
Blood tests
  Complete blood count
  Serum chemistry panel (CHEM-20, comprehensive metabolic panel)Assesses current status of metabolism. Includes liver function tests (e.g., alkaline phosphate, alanine amino transferase, aspartate amino transferase, bilirubin), kidney function tests (e.g., blood urea nitrogen and creati nine), electrolytes (e.g., sodium, potassium, chloride), glucose, and calcium.
  Lipid panelMany medications affect lipid levels; therefore, it is important to have baseline measures on which to compare. Includes total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides.
  Thyroid function tests (thyroid-stimulating hormone [TSH], free T3, and free T4)To rule out thyroid dysfunction as a common mimic to psychiatric symptoms. T3 measures unbound triiodothyronine, and T4 measures unbound thyroxine.
  Screening tests for HIV, hepatitis C, and syphilisRecommended by the Centers for Disease Control and Prevention for at-risk populations and to clarify cognitive deficits.
  Serum B12Vitamin B12 deficiency is a common condition that affects blood cell production and brain and nerve function. Low levels require further clarification with homocysteine and holotranscobalamin serum levels.
  Pregnancy tests in women of childbearing ageMany psychotropic drugs affect fetal development.
Urine
  Urine drug toxicologyTo screen for substance use, including alcohol, amphetamines, benzodiazepines, cannabinoids, cocaine, opioids, phencyclidine, and tricyclic antidepressants.
  UrinalysisTo screen for kidney and urinary tract diseases. Includes specific gravity, pH, bilirubin, urobilinogen, protein, glucose, ketones, blood and myoglobin, red and white blood cells, bacteria, casts, and crystals.
Cardiac
  Electrocardiogram with QT correctionAssesses heart rate and rhythm. Many psychotropic medications prolong the QT interval; therefore, baseline measures are essential for further assessment.
Authors

Dr. Limandri is Professor Emerita, Linfield College, School of Nursing, McMinnville, Oregon.

The author has disclosed no potential conflicts of interest, financial or otherwise.

Address correspondence to Barbara J. Limandri, PhD, PMHNP, BC, Professor Emerita, 9136 SW 36th Avenue, Portland, OR 97219; e-mail: limandribj@gmail.com.

10.3928/02793695-20190713-01

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