Evaluation of Potential Racial Disparities in CYP2C19-Guided P2Y12 Inhibitor Prescribing After Percutaneous Coronary Intervention.

Black patients suffer worse outcomes after percutaneous coronary intervention (PCI) than White patients. Inequities in antiplatelet prescribing may contribute to this health disparity. We compared P2Y12 inhibitor prescribing by race following CYP2C19 genotyping to guide antiplatelet therapy selection after PCI. Patients from 9 sites that performed clinical CYP2C19 genotyping after PCI were included. Alternative therapy (e.g., prasugrel or ticagrelor) was recommended for CYP2C19 no-function allele carriers, in whom clopidogrel is predicted to be less effective. The primary outcome was choice of P2Y12 inhibitor (clopidogrel vs. alternative therapy) based on genotype. Of 3,342 patients included, 2,448 (73%) were White, and 659 (20%) were Black. More Black than White patients had a no-function allele (34.3% vs. 29.7%, P = 0.024). At hospital discharge following PCI, 44.2% of Black and 44.0% of White no-function allele carriers were prescribed alternative therapy. At the time of the last follow-up within 12 months, numerically fewer Black (51.8%) than White (56.7%) no-function allele carriers were prescribed alternative therapy (P = 0.190). However, the difference was not significant after accounting for other factors associated with P2Y12 inhibitor selection (odds ratio 0.79, 95% confidence interval 0.58-1.08). Alternative therapy use did not differ between Black (14.3%) and White (16.7%) patients without a no-function allele (P = 0.232). Among real-world patients who received CYP2C19 testing after PCI, P2Y12 inhibitor prescribing rates did not differ between Black and White patients. Our data suggest an absence of racial disparity in genotype-guided antiplatelet prescribing among patients receiving CYP2C19 testing.

Implementing Pharmacogenetic Testing in Gastrointestinal Cancers (IMPACT-GI): Study Protocol for a Pragmatic Implementation Trial for Establishing DPYD and UGT1A1 Screening to Guide Chemotherapy Dosing.

Background: Fluoropyrimidines (fluorouracil [5-FU], capecitabine) and irinotecan are commonly prescribed chemotherapy agents for gastrointestinal (GI) malignancies. Pharmacogenetic (PGx) testing for germline DPYD and UGT1A1 variants associated with reduced enzyme activity holds the potential to identify patients at high risk for severe chemotherapy-induced toxicity. Slow adoption of PGx testing in routine clinical care is due to implementation barriers, including long test turnaround times, lack of integration in the electronic health record (EHR), and ambiguity in test cost coverage. We sought to establish PGx testing in our health system following the Exploration, Preparation, Implementation, Sustainment (EPIS) framework as a guide. Our implementation study aims to address barriers to PGx testing. Methods: The Implementing Pharmacogenetic Testing in Gastrointestinal Cancers (IMPACT-GI) study is a non-randomized, pragmatic, open-label implementation study at three sites within a major academic health system. Eligible patients with a GI malignancy indicated for treatment with 5-FU, capecitabine, or irinotecan will undergo PGx testing prior to chemotherapy initiation. Specimens will be sent to an academic clinical laboratory followed by return of results in the EHR with appropriate clinical decision support for the care team. We hypothesize that the availability of a rapid turnaround PGx test with specific dosing recommendations will increase PGx test utilization to guide pharmacotherapy decisions and improve patient safety outcomes. Primary implementation endpoints are feasibility, fidelity, and penetrance. Exploratory analyses for clinical effectiveness of genotyping will include assessing grade ≥3 treatment-related toxicity using available clinical data, patient-reported outcomes, and quality of life measures. Conclusion: We describe the formative work conducted to prepare our health system for DPYD and UGT1A1 testing. Our prospective implementation study will evaluate the clinical implementation of this testing program and create the infrastructure necessary to ensure sustainability of PGx testing in our health system. The results of this study may help other institutions interested in implementing PGx testing in oncology care. Clinical Trial Registration: https://clinicaltrials.gov/ct2/show/NCT04736472, identifier [NCT04736472].

Pharmacogenetic variants and risk of remdesivir-associated liver enzyme elevations in Million Veteran Program participants hospitalized with COVID-19.

Remdesivir is the first US Food and Drug Administration (FDA)-approved drug for the treatment of coronavirus disease 2019 (COVID-19). We conducted a retrospective pharmacogenetic study to examine remdesivir-associated liver enzyme elevation among Million Veteran Program participants hospitalized with COVID-19 between March 15, 2020, and June 30, 2021. Pharmacogene phenotypes were assigned using Stargazer. Linear regression was performed on peak log-transformed enzyme values, stratified by population, adjusted for age, sex, baseline liver enzymes, comorbidities, and 10 population-specific principal components. Patients on remdesivir had higher peak alanine aminotransferase (ALT) values following treatment initiation compared with patients not receiving remdesivir. Remdesivir administration was associated with a 33% and 24% higher peak ALT in non-Hispanic White (NHW) and non-Hispanic Black (NHB) participants (p < 0.001), respectively. In a multivariable model, NHW CYP2C19 intermediate/poor metabolizers had a 9% increased peak ALT compared with NHW normal/rapid/ultrarapid metabolizers (p = 0.015); this association was not observed in NHB participants. In summary, remdesivir-associated ALT elevations appear to be multifactorial, and further studies are needed.

The Clinical Pharmacogenetics Implementation Consortium Guideline for SLCO1B1, ABCG2, and CYP2C9 genotypes and Statin-Associated Musculoskeletal Symptoms.

Statins reduce cholesterol, prevent cardiovascular disease, and are among the most commonly prescribed medications in the world. Statin-associated musculoskeletal symptoms (SAMS) impact statin adherence and ultimately can impede the long-term effectiveness of statin therapy. There are several identified pharmacogenetic variants that impact statin disposition and adverse events during statin therapy. SLCO1B1 encodes a transporter (SLCO1B1; alternative names include OATP1B1 or OATP-C) that facilitates the hepatic uptake of all statins. ABCG2 encodes an efflux transporter (BCRP) that modulates the absorption and disposition of rosuvastatin. CYP2C9 encodes a phase I drug metabolizing enzyme responsible for the oxidation of some statins. Genetic variation in each of these genes alters systemic exposure to statins (i.e., simvastatin, rosuvastatin, pravastatin, pitavastatin, atorvastatin, fluvastatin, lovastatin), which can increase the risk for SAMS. We summarize the literature supporting these associations and provide therapeutic recommendations for statins based on SLCO1B1, ABCG2, and CYP2C9 genotype with the goal of improving the overall safety, adherence, and effectiveness of statin therapy. This document replaces the 2012 and 2014 Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines for SLCO1B1 and simvastatin-induced myopathy.

Identifying Racial, Ethnic, and Socioeconomic Inequities in the Use of Novel P2Y12 Inhibitors After Percutaneous Coronary Intervention.

BACKGROUND: Novel P2Y12 inhibitors prasugrel and ticagrelor were approved for patients with acute coronary syndrome (ACS) in 2009 and 2011, respectively. We assessed the association of racial, ethnic, and socioeconomic factors with initiation of and adherence to novel P2Y12 inhibitors in a commercially insured population. METHODS: We performed a retrospective cohort analysis of adults undergoing percutaneous coronary intervention with placement of a drug-eluting stent, stratified by ACS status, between January 2008 and December 2016 using Clinformatics Data Mart (OptumInsight). We estimated multivariable logistic regression models to identify factors associated with the initiation of clopidogrel vs novel P2Y12 inhibitors as well as subsequent 6-month medication adherence, assessed via pharmacy records. RESULTS: A total of 55,664 patients were included in the analysis. Hispanic ethnicity was independently associated with the initiation of clopidogrel compared with novel P2Y12 inhibitors among ACS patients (odds ratio [OR], 1.19; 95% confidence interval [CI], 1.04-1.36; P<.01). ACS patients with an annual median household income of over $100,000 were less likely to be started on clopidogrel when compared with those who earned less than $40,000 (OR, 0.67; 95% CI, 0.61-0.75; P<.01). Black race, Hispanic ethnicity, and lower household income were each associated with significantly reduced odds of P2Y12 inhibitor adherence. CONCLUSION: Hispanic ethnicity and lower household income were associated with novel P2Y12 inhibitor initiation, and non-White race and ethnicity were associated with lower P2Y12 inhibitor adherence over 6-month follow-up. These findings highlight continued inequity of care, even in an insured population, and point to a need for new strategies to close these gaps.

Preemptive pharmacogenetic testing to guide chemotherapy dosing in patients with gastrointestinal malignancies: a qualitative study of barriers to implementation.

BACKGROUND: Pharmacogenetic (PGx) testing for germline variants in the DPYD and UGT1A1 genes can be used to guide fluoropyrimidine and irinotecan dosing, respectively. Despite the known association between PGx variants and chemotherapy toxicity, preemptive testing prior to chemotherapy initiation is rarely performed in routine practice. METHODS: We conducted a qualitative study of oncology clinicians to identify barriers to using preemptive PGx testing to guide chemotherapy dosing in patients with gastrointestinal malignancies. Each participant completed a semi-structured interview informed by the Consolidated Framework for Implementation Research (CFIR). Interviews were analyzed using an inductive content analysis approach. RESULTS: Participants included sixteen medical oncologists and nine oncology pharmacists from one academic medical center and two community hospitals in Pennsylvania. Barriers to the use of preemptive PGx testing to guide chemotherapy dosing mapped to four CFIR domains: intervention characteristics, outer setting, inner setting, and characteristics of individuals. The most prominent themes included 1) a limited evidence base, 2) a cumbersome and lengthy testing process, and 3) a lack of insurance coverage for preemptive PGx testing. Additional barriers included clinician lack of knowledge, difficulty remembering to order PGx testing for eligible patients, challenges with PGx test interpretation, a questionable impact of preemptive PGx testing on clinical care, and a lack of alternative therapeutic options for some patients found to have actionable PGx variants. CONCLUSIONS: Successful adoption of preemptive PGx-guided chemotherapy dosing in patients with gastrointestinal malignancies will require a multifaceted effort to demonstrate clinical effectiveness while addressing the contextual factors identified in this study.

DPYD and UGT1A1 Pharmacogenetic Testing in Patients with Gastrointestinal Malignancies: An Overview of the Evidence and Considerations for Clinical Implementation.

Gastrointestinal (GI) malignancies are among the most commonly diagnosed cancers worldwide. Despite the introduction of targeted and immunotherapy agents in the treatment landscape, cytotoxic agents, such as fluoropyrimidines and irinotecan, remain as the cornerstone of chemotherapy for many of these tumors. Pharmacogenetics (PGx) is a rapidly evolving field that accounts for interpatient variability in drug metabolism to predict therapeutic response and toxicity. Given the significant incidence of severe treatment-related adverse events associated with cytotoxic agents, utilizing PGx can allow clinicians to better anticipate drug tolerability while minimizing treatment interruptions or delays. In this review, the PGx profiles of drug-gene pairs with potential impact in GI malignancy therapy - DPYD-5-fluorouracil/capecitabine and UGT1A1-irinotecan - and the available clinical evidence of their roles in reducing severe adverse events are discussed. Considerations for clinical implementation, such as optimal laboratory workflows, electronic health record integration, and stakeholder engagement, as well as provider education, are addressed. Last, exploratory PGx markers in GI malignancy treatment are described. As the PGx knowledge base rapidly evolves, pharmacists will be vital in leveraging their pharmacology knowledge and clinical skills to implement PGx testing in the clinic.

Projected Prevalence of Actionable Pharmacogenetic Variants and Level A Drugs Prescribed Among US Veterans Health Administration Pharmacy Users.

Importance: Implementation of pharmacogenetic testing to guide drug prescribing has potential to improve drug response and prevent adverse events. Robust data exist for more than 30 gene-drug pairs linking genotype to drug response phenotypes; however, it is unclear which pharmacogenetic tests, if implemented, would provide the greatest utility for a given patient population. Objectives: To project the proportion of veterans in the US Veterans Health Administration (VHA) with actionable pharmacogenetic variants and evaluate how testing might be associated with prescribing decisions. Design, Setting, and Participants: This cross-sectional study included veterans who used national VHA pharmacy services from October 1, 2011, to September 30, 2017. Data analyses began April 26, 2018, and were completed February 6, 2019. Exposures: Receipt of level A drugs based on VHA pharmacy dispensing records. Main Outcomes and Measures: Projected prevalence of actionable pharmacogenetic variants among VHA pharmacy users based on variant frequencies from the 1000 Genomes Project and veteran demographic characteristics; incident number of level A prescriptions, and proportion of new level A drug recipients projected to carry an actionable pharmacogenetic variant. Results: During the study, 7 769 359 veterans (mean [SD] age, 58.1 [17.8] years; 7 021 504 [90.4%] men) used VHA pharmacy services. It was projected that 99% of VHA pharmacy users would carry at least 1 actionable pharmacogenetic variant. Among VHA pharmacy users, 4 259 153 (54.8%) received at least 1 level A drug with 1 188 124 (15.3%) receiving 2 drugs, and 912 189 (11.7%) receiving 3 or more drugs. The most common incident prescriptions during the study were tramadol (923 671 new recipients), simvastatin (533 928 new recipients), citalopram (266 952 new recipients), and warfarin (205 177 new recipients). Gene-drug interactions projected to have substantial clinical impacts in the VHA population include the interaction of SLCO1B1 with simvastatin (1 988 956 veterans [25.6%]), CYP2D6 with tramadol (318 544 veterans [4.1%]), and CYP2C9 or VKORC1 with warfarin (7 163 349 veterans [92.2%]). Conclusions and Relevance: Clinically important pharmacogenetic variants are highly prevalent in the VHA population. Almost all veterans would carry an actionable variant, and more than half of the population had been exposed to a drug affected by these variants. These results suggest that pharmacogenetic testing has the potential to affect pharmacotherapy decisions for commonly prescribed outpatient medications for many veterans.

Trends in Platelet Adenosine Diphosphate P2Y12 Receptor Inhibitor Use and Adherence Among Antiplatelet-Naive Patients After Percutaneous Coronary Intervention, 2008-2016.

Importance: Current guidelines recommend prasugrel hydrochloride and ticagrelor hydrochloride as preferred therapies for patients with acute coronary syndrome (ACS) treated with percutaneous coronary intervention (PCI). However, it is not well known how frequently these newer agents are being used in clinical practice or how adherence varies among the platelet adenosine diphosphate P2Y12 receptor (P2Y12) inhibitors. Objectives: To determine trends in use of the different P2Y12 inhibitors in patients who underwent PCI from 2008 to 2016 in a large cohort of commercially insured patients and differences in patient adherence and costs among the P2Y12 inhibitors. Design, Setting, and Participants: A retrospective cohort study used administrative claims from a large US national insurer (ie, UnitedHealthcare) from January 1, 2008, to December 1, 2016, comprising patients aged 18 to 64 years hospitalized for PCI who had not received a P2Y12 inhibitor for 90 days preceding PCI. The P2Y12 inhibitor filled within 30 days of discharge was identified from pharmacy claims. Main Outcomes and Measures: Proportion of patients filling prescriptions for P2Y12 inhibitors within 30 days of discharge by year, as well as medication possession ratios (MPRs) and total P2Y12 inhibitor copayments at 6 and 12 months for patients who received drug-eluting stents. Results: A total of 55 340 patients (12 754 [23.0%] women; mean [SD] age, 54.4 [7.1] years) who underwent PCI were included in this study. In 2008, 7667 (93.6%) patients filled a prescription for clopidogrel bisulfate and 521 (6.4%) filled no P2Y12 inhibitor prescription within 30 days of hospitalization. In 2016, 2406 (44.0%) patients filled clopidogrel prescriptions, 2015 (36.9%) filled either prasugrel or ticagrelor prescriptions, and 1045 (19.1%) patients filled no P2Y12 inhibitor prescription within 30 days of hospitalization. At 6 months, mean MPRs for patients who received a drug-eluting stent filling clopidogrel, prasugrel, and ticagrelor prescriptions were 0.85 (interquartile range [IQR], 0.82-1.00), 0.79 (IQR, 0.66-1.00), and 0.76 (IQR, 0.66-0.98) (P < .001), respectively; mean copayments for a 6 months' supply were $132 (IQR, $47-$203), $287 (IQR, $152-$389), and $265 (IQR, $53-$387) (P < .001), respectively. At 12 months, mean MPRs for clopidogrel, prasugrel, and ticagrelor were 0.76 (IQR, 0.58-0.99), 0.71 (IQR, 0.49-0.98), and 0.68 (IQR, 0.41-0.94) (P < .001), respectively; mean total copayments were $251 (IQR, $100-$371), $556 (IQR, $348-$730), and $557 (IQR, $233-$744) (P < .001), respectively. Conclusions and Relevance: Between 2008 and 2016, increased use of prasugrel and ticagrelor was accompanied by increased nonfilling of prescriptions for P2Y12 inhibitors within 30 days of discharge. Prasugrel and ticagrelor had higher patient costs and lower adherence in the year following PCI compared with clopidogrel. The introduction of newer, more expensive P2Y12 inhibitors was associated with lower adherence to these therapies.

Antiplatelet Therapy for Secondary Prevention of Vascular Disease Complications.

PURPOSE OF REVIEW: Platelets are activated upon interaction with injured vascular endothelium to form a primary hemostatic plug. Pathogenic thrombosis driven by platelet aggregation can occur in the setting of vascular disease leading to ischemic events. The use of antiplatelet agents has become a mainstay for prevention of the secondary complications of vascular disease. This review summarizes seminal and recent literature related to this area. RECENT FINDINGS: Aspirin is a cornerstone of antiplatelet therapy for coronary artery disease and cerebrovascular disease for prevention of myocardial infarction, stroke, and vascular death. Alternative antiplatelet agents have shown promise for use in patients with peripheral artery disease though further validation is necessary. Dual antiplatelet therapy (DAPT) with clopidogrel, prasugrel, or ticagrelor, and aspirin demonstrates benefit in patients with higher thrombotic risk. However, use of DAPT predictably increases bleeding risk, thus limiting mortality benefit. Individualization of DAPT to patient-specific features is an area of active research with the development the DAPT score and pharmacogenomic approaches. Application of pharmacogenetic data could allow for a precision medicine approach to tailoring antiplatelet therapy. Recommendations for management of cardiovascular, cerebrovascular, and peripheral artery disease are largely based on large-scale randomized control trials and meta-analyses. Seminal trials have largely focused on prevention of vascular events including non-fatal MI, stroke, and vascular death in subsets of patients with cardiovascular disease. Data from these trials along with smaller studies have driven recommendations for secondary prevention management in patients with cerebrovascular and peripheral artery disease.

Expression of Calgranulin Genes S100A8, S100A9 and S100A12 Is Modulated by n-3 PUFA during Inflammation in Adipose Tissue and Mononuclear Cells.

Calgranulin genes (S100A8, S100A9 and S100A12) play key immune response roles in inflammatory disorders, including cardiovascular disease. Long-chain omega-3 polyunsaturated fatty acids (LC n-3 PUFA) may have systemic and adipose tissue-specific anti-inflammatory and cardio-protective action. Interactions between calgranulins and the unsaturated fatty acid arachidonic acid (AA) have been reported, yet little is known about the relationship between calgranulins and the LC n-3 PUFA eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). We explored tissue-specific action of calgranulins in the setting of evoked endotoxemia and n-3 PUFA supplementation. Expression of calgranulins in adipose tissue in vivo was assessed by RNA sequencing (RNASeq) before and after n-3 PUFA supplementation and evoked endotoxemia in the fenofibrate and omega-3 fatty acid modulation of endotoxemia (FFAME) Study. Subjects received n-3 PUFA (n = 8; 3600mg/day EPA/DHA) or matched placebo (n = 6) for 6-8 weeks, before completing an endotoxin challenge (LPS 0.6 ng/kg). Calgranulin genes were up-regulated post-LPS, with greater increase in n-3 PUFA (S100A8 15-fold, p = 0.003; S100A9 7-fold, p = 0.003; S100A12 28-fold, p = 0.01) compared to placebo (S100A8 2-fold, p = 0.01; S100A9 1.4-fold, p = 0.4; S100A12 5-fold, p = 0.06). In an independent evoked endotoxemia study, calgranulin gene expression correlated with the systemic inflammatory response. Through in vivo and in vitro interrogation we highlight differential responses in adipocytes and mononuclear cells during inflammation, with n-3 PUFA leading to increased calgranulin expression in adipose, but decreased expression in circulating cells. In conclusion, we present a novel relationship between n-3 PUFA anti-inflammatory action in vivo and cell-specific modulation of calgranulin expression during innate immune activation.

Measuring niacin-associated skin toxicity (NASTy) stigmata along with symptoms to aid development of niacin mimetics.

Though cardioprotective, niacin monotherapy is limited by unpleasant cutaneous symptoms mimicking dermatitis: niacin-associated skin toxicity (NASTy). Niacin is prototypical of several emerging drugs suffering off-target rubefacient properties whereby agonizing the GPR109A receptor on cutaneous immune cells provokes vasodilation, prompting skin plethora and rubor, as well as dolor, tumor, and calor, and systemically, heat loss, frigor, chills, and rigors. Typically, NASTy effects are described by subjective patient-reported perception, at best semi-quantitative and bias-prone. Conversely, objective, quantitative, and unbiased methods measuring NASTy stigmata would facilitate research to abolish them, motivating development of several objective methods. In early drug development, such methods might better predict clinical tolerability in larger clinical trials. Measuring cutaneous stigmata may also aid investigations of vasospastic, ischemic, and inflammatory skin conditions. We present methods to measure NASTy physical stigmata to facilitate research into novel niacin mimetics/analogs, detailing characteristics of each technique following niacin, and how NASTy stigmata relate to symptom perception. We gave niacin orally and measured rubor by colorimetry and white-light spectroscopy, plethora by laser Doppler flowmetry, and calor/frigor by thermometry. Surprisingly, each stigma's abruptness predicted symptom perception, whereas peak intensity did not. These methods are adaptable to study other rubefacient drugs or dermatologic and vascular disorders.

Simvastatin-ezetimibe-induced hepatic failure necessitating liver transplantation.

Abstract Serum aminotransferase elevations are a commonly known adverse effect of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor (statin) therapy. However, hepatotoxic events have not been widely published with ezetimibe or the combination agent simvastatin-ezetimibe. We describe a 70-year-old Hispanic woman who developed fulminant hepatic failure necessitating liver transplantation 10 weeks after conversion from simvastatin 40 mg/day to simvastatin 10 mg-ezetimibe 40 mg/day. The patient's lipid panel had been maintained with simvastatin for 18 months before the conversion without evidence of hepatotoxicity. A routine laboratory work-up 10 weeks after conversion revealed elevated serum aminotransferase levels. Simvastatinezetimibe and escitalopram (which she was taking for depression) were discontinued, and other potential causes of hepatotoxicity were excluded. A repeat work-up revealed further elevations in aminotransferase levels, and liver biopsy revealed evidence of moderate-to-severe drug toxicity. She underwent liver transplantation with an uneventful postoperative course. Her aminotransferase levels returned to normal by postoperative day 23, and her 2-year follow-up showed no adverse events. Ezetimibe undergoes extensive glucuronidation by uridine diphosphate glucoronosyltransferases (UGT) in the intestine and liver and may have inhibited the glucuronidation of simvastatin hydroxy acid, resulting in increased simvastatin exposure and subsequent hepatotoxicity. To our knowledge, this is the first case report of simvastatin-ezetimibe-induced liver failure that resulted in liver transplantation. We postulate that the mechanism of the simvastatinezetimibe-induced hepatotoxicity is the increased simvastatin exposure by ezetimibe inhibition of UGT enzymes. Clinicians should be aware of potential hepatotoxicity with simvastatin-ezetimibe especially in elderly patients and should carefully monitor serum aminotransferase levels when starting therapy and titrating the dosage.

Utilization of dried blood spot citrulline level as a noninvasive method for monitoring graft function following intestinal transplantation.

BACKGROUND: Citrulline concentrations have been proposed as a marker for intestinal allograft rejection. We instituted dried blood spot (DBS) specimen monitoring of citrulline to simplify sample collection posttransplant. This study demonstrates the correlation between plasma and dried blood spot specimen citrulline concentrations after intestinal transplantation. METHODS: Plasma and DBS samples were analyzed by hydrophilic interaction chromatography tandem mass spectrometry. Comparison of the strength of linear correlation was made according to the type of surgery, sonication time, DBS citrulline levels, and the time interval between the blood sample collection and the assay date. RESULTS: A very strong linear correlation exists between the plasma and DBS citrulline concentrations (r=0.87; P<0.001). The correlation between plasma and DBS citrulline concentrations was maintained when evaluating only the intestinal transplant recipients. There was no significant difference in the strength of linear correlation according to sonication time, cirtrulline concentrations, or length of time to assay date. CONCLUSIONS: DBS citrulline monitoring will ease sample collection following intestinal transplantation and improve the ability to detect intestinal dysfunction and rejection by a noninvasive means.

Trospium chloride for the treatment of overactive bladder with urge incontinence.

BACKGROUND: Urinary incontinence is caused by an overactive bladder, leading to symptoms of urgency, frequency, and incontinence. Urge incontinence occurs predominantly in women as they age. OBJECTIVES: This article reviews the current primary literature concerning the efficacy and tolerability of the anticholinergic agent trospium chloride (TCl) in the treatment of overactive bladder with symptoms of urge incontinence, urgency, and frequency. The pharmacokinetics of TCl are also reviewed. METHODS: Pertinent articles in English were identified through a search of MEDLINE (1966-present), EMBASE Drugs & Pharmacology (1980-third quarter 2004), Current Contents/Clinical Medicine (week 42, 2003-week 41, 2004), Cochrane Database of Systematic Reviews, MICROMEDEX Healthcare Series, and International Pharmaceutical Abstracts (1970-present). The search terms were overactive bladder, urinary incontinence, trospium, randomized controlled clinical trial, oxybutynin, tolterodine, scopolamine, imipramine, desipramine, and propantheline. RESULTS: TCl, a quaternary amine, exhibits high solubility in water but low oral bioavailability (9.6%) and poor central nervous system penetration. Approximately 80% of the absorbed fraction is renally eliminated as unchanged drug via active tubular secretion, with approximately 15% hepatically metabolized into a spiroalcohol and hydrolysis/oxidation products. In 3 placebo-controlled studies, patients who received TCl had an increase in maximum bladder filling capacity and bladder compliance, with a reduction in maximum cystometric capacity (P < 0.005); however, only 1 of these studies showed an increase in bladder compliance, with reductions in maximum detrusor pressure (P < 0.001), number of voids/d (P < or = 0.001), and incontinence episodes/d (P < or = 0.001). In another placebo-controlled study, TCl reduced the number of voids/d and incontinence episodes/d (both, P < or = 0.001). In 2 double-blind studies, TCl and oxybutynin were similarly effective in significantly increasing maximum cystometric capacity and bladder compliance, and in significantly reducing maximum detrusor pressure compared with baseline (all, P < 0.001); there were no significant differences between the 2 treatments at end point. In a third double-blind study comparing TCl and tolterodine with placebo, only TCl significantly reduced the frequency of micturitions/d (P = 0.01). Commonly reported adverse effects in patients receiving TCl included dry mouth, constipation, and headache. CONCLUSIONS: In the 7 studies reviewed, TCl was effective and well tolerated in patients with urge incontinence caused by idiopathic detrusor muscle overactivity or neurogenic detrusor overactivity resulting from spinal cord injury. However, this agent was associated with anticholinergic adverse effects similar to those of other anticholinergic agents; careful monitoring of tolerability is required.