This study assesses the utilization of antipsychotic therapeutic drug monitoring (TDM) and describes characteristics of appropriate and inappropriate TDM at a state psychiatric hospital. A retrospective, descriptive review was conducted for antipsychotic TDM completed between December 1, 2009, and June 30, 2011, at a 65-bed adult inpatient extended-care and forensic state psychiatric hospital. One hundred thirty-three (n = 133) antipsychotic serum levels were collected from 44 patients during the study period. Sixty-nine percent (69%) of the TDM were deemed inappropriate, 28% were appropriate, and 3% could not be designated appropriate or inappropriate owing to the lack of information regarding steady-state conditions. The primary reason for inappropriate TDM was lack of documentation with regard to the indication for TDM (n = 79, 59.3%), the intervention following laboratory analysis (n = 88, 66%), or both. Appropriate TDM was associated with a lower laboratory cost for antipsychotic serum level ($48.98 ± $53.49 versus $72.06 ± $51.02, P < .05), lower daily cost of scheduled psychiatric medications ($17.72 ± $23.03 versus $32.26 ± $31.05, P < .05), lower daily cost of total medications ($19.28 ± $24.91 versus $33.82 ± $31.03, P < .05), fewer scheduled psychiatric medications (2.95 ± 1.90 versus 4.04 ± 2.19, P < .01), and fewer total scheduled medications (5.95 ± 3.60 versus 7.60 ± 3.29, P < .05). Inappropriate TDM led to approximately $6,753 in avoidable laboratory costs over a 20-month period. Therapeutic drug monitoring is a complex process with many points at which errors may occur. The majority of antipsychotic levels at this state psychiatric hospital were not documented in a way that was clinically useful. Inappropriate TDM was associated with increased laboratory and medication costs.Abstract
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Antiepileptic drugs (AEDs) are routinely prescribed for the management of a variety of neurologic and psychiatric conditions, including epilepsy and epilepsy syndromes. Physiologic changes due to aging, pregnancy, nutritional status, drug interactions, and diseases (ie, those involving liver and kidney function) can affect pharmacokinetics of AEDs. This review discusses foundational pharmacokinetic characteristics of AEDs currently available in the United States, including clobazam but excluding the other benzodiazepines. Commonalities of pharmacokinetic properties of AEDs are discussed in detail. Important differences among AEDs and clinically relevant pharmacokinetic interactions in absorption, distribution, metabolism, and/or elimination associated with AEDs are highlighted. In general, newer AEDs have more predictable kinetics and lower risks for drug interactions. This is because many are minimally or not bound to serum proteins, are primarily renally cleared or metabolized by non–cytochrome P450 isoenzymes, and/or have lower potential to induce/inhibit various hepatic enzyme systems. A clear understanding of the pharmacokinetic properties of individual AEDs is essential in creating a safe and effective treatment plan for a patient.Abstract
Antipsychotics are widely used and often in combination with other drugs, thereby frequently subjected to drug-drug interactions. This review will provide a summary of potential pharmacokinetic (PK) and pharmacodynamic (PD) drug interactions associated with antipsychotic drugs. A literature search was conducted for clinically significant drug interactions with antipsychotics. Most common PK drug interactions take place via the cytochrome P450 (CYP) system. PK profiles of first generation antipsychotics are inadequately studied; nevertheless most common drug interactions involve changes to their metabolic processes. Interactions with second generation antipsychotics are somewhat well-established, documented, and give some guidance for therapeutic treatment interventions. PD interactions occurring at the receptor level result in additive, synergistic, or antagonistic effects. This review summarizes a collection of relevant literature of significant PK and PD interactions occurring with antipsychotics. The involvement of multiple CYP enzymes makes it more difficult to predict the extent of the interaction and clinicians should take into consideration the timeline when evaluating potential interactions.Abstract
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The goal of pharmacogenetic research is to assist clinicians in predicting patient response to medications when genetic variations are identified. The pharmacogenetic variation of antiepileptic drug response and side effects has yielded findings that have been included in drug labeling and guidelines. The goal of this review is to provide a brief overview of the pharmacogenetic research on antiepileptic drugs. It will focus on findings that have been included in drug labeling, guidelines, and candidate pharmacogenetic variation. Overall, several genes have been included in guidelines by national and international organizations; however, much work is needed to implement and evaluate their use in clinical settings.Abstract
Treatment of depression often requires long-term management with medication. Practitioners should be aware of potentially significant drug interactions with the use of antidepressants in order to effectively prevent or manage adverse events while optimizing patient response to treatment. Most antidepressants are metabolized by the liver, primarily via the CYP450 system. Pharmacokinetic profiles of the most recently approved antidepressants are reviewed in addition to evidence supporting potentially significant interactions. In addition, pharmacokinetic interactions between multiple antidepressants and other drug classes, including opiates, antineoplastics, antiepileptics, and antipsychotics, are discussed. This article provides recommendations for the monitoring and management of drug interactions. In addition, limitations of the evidence are reviewed.Abstract
Proper psychiatric evaluation of patients necessitates that the clinician be vigilant in ruling out secondary causes of symptoms, such as substance-induced symptoms. Immunoassay-type urine drug screens (UDSs) offer clinicians rapid drug screen results, ease of use, and inexpensive cost. Unfortunately, these screens are not without their limitations. This review aims to outline the nuances and limitations of immunoassay UDSs and to provide the clinician with information that facilitates more accurate interpretation of UDS results. Specifically, false positive results associated with psychiatric medications and the availability and methods for acquisition of commercialized UDS masking agents will be reviewed. A literature review was conducted to identify false positive UDSs associated with psychiatric medications. References for each article identified were also reviewed. Additionally, a Google® search was conducted to identify commercially available preparations used to mask UDS results and the methods of acquisition of these products. A total of 14 articles were identified using PubMed. No articles for mood stabilizing agents were identified. Entering the phrase how to pass a drug test into Google® search yielded about 12.6 million results, and select references were reviewed based on relevance and user reviews. Several psychiatric medications are documented as potential sources of false positive UDSs. Additionally, several agents are available for consumer purchase that may result in false negative UDSs. The clinician must be vigilant in interpreting immunoassay UDS results and should utilize more advanced forms of testing as clinically appropriate.Abstract
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The study of pharmacogenomics is rapidly growing, particularly in the field of mental health. Understanding pharmacogenomic principles can be a challenge for many clinicians. Most mental health genomic data concentrates on variability (response, side effects) with antidepressants and atypical antipsychotics. Current pharmacogenomic practice and research primarily focuses on two areas: pharmacodynamics and pharmacokinetics. Based on the current literature, genetic polymorphisms of pharmacodynamics and pharmacokinetics parameters likely influence medication efficacy, therefore affecting the therapeutic benefit. Additionally, certain pharmacodynamic and pharmacokinetic polymorphisms have been linked to an elevated risk of side effects and adverse events with these medications. In this review, specific pharmacodynamic and pharmacokinetic polymorphisms related to antidepressants and atypical antipsychotics will be discussed, as well as the potential clinical effect these genomic abnormalities have within psychiatric care.Abstract
Mood stabilizers are the recommended treatment for patients who receive a diagnosis of bipolar disorder. Because of the necessity of mood stabilizer treatment in patients with bipolar disorder and the extent of pharmacokinetic and pharmacodynamic principles involved, the purpose of this review is to summarize the pharmacokinetic principles of lithium in addition to the pharmacodynamics of lithium, carbamazepine, lamotrigine, and valproic acid/valproate. Practice guidelines, review articles, and clinical trials were located using online databases PubMed, CINAHL, IDIS, and Medline. Search terms included at least one of the following: bipolar disorder, carbamazepine, lamotrigine, lithium, mood stabilizers, pharmacokinetics, pharmacodynamics, valproate, and valproic acid. Online clinical databases Dynamed® and Lexicomp® were also used in the study. Mood stabilizers collectively possess distinct qualities that are closely regarded before, during, and after therapeutic initiation. Individual patient characteristics, coupled with these observed traits, add to the complexity of selecting the most optimal neurologic agent. Each medication discussed uniquely contributes to both the maintenance and restoration of overall patient well-being. Introduction of mood stabilizers into drug regimens is often done in the presence of an array of mitigating factors. Safety and efficacy measures are commonly used to gauge desired results. Careful monitoring of patients' responses to selected therapies is paramount for arriving at appropriate clinical outcomes.Abstract
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