Browsing by Subject "Pharmacokinetics"

Now showing 1 - 10 of 59
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    A multicenter study to evaluate the pharmacokinetics and safety of liposomal bupivacaine for postsurgical analgesia in pediatric patients aged 6 to less than 17 years (PLAY)
    (Elsevier, 2021) Tirotta, Christopher F.; de Armendi, Alberto J.; Horn, Nicole D.; Hammer, Gregory B.; Szczodry, Michal; Matuszczak, Maria; Wang, Natalie Q.; Scranton, Richard; Ballock, Robert Tracy; Anesthesia, School of Medicine
    Study objective: To evaluate the pharmacokinetics and safety of liposomal bupivacaine in pediatric patients undergoing spine or cardiac surgery. Design: Multicenter, open-label, phase 3, randomized trial (PLAY; NCT03682302). Setting: Operating room. Patients: Two separate age groups were evaluated (age group 1: patients 12 to <17 years undergoing spine surgery; age group 2: patients 6 to <12 years undergoing spine or cardiac surgery). Intervention: Randomized allocation of liposomal bupivacaine 4 mg/kg or bupivacaine hydrochloride (HCl) 2 mg/kg via local infiltration at the end of spine surgery (age group 1); liposomal bupivacaine 4 mg/kg via local infiltration at the end of spine or cardiac surgery (age group 2). Measurements: The primary and secondary objectives were to evaluate the pharmacokinetics (eg, maximum plasma bupivacaine concentrations [Cmax], time to Cmax) and safety of liposomal bupivacaine, respectively. Main results: Baseline characteristics were comparable across groups. Mean Cmax after liposomal bupivacaine administration was lower versus bupivacaine HCl in age group 1 (357 vs 564 ng/mL); mean Cmax in age group 2 was 320 and 447 ng/mL for spine and cardiac surgery, respectively. Median time to Cmax of liposomal bupivacaine occurred later with cardiac surgery versus spine surgery (22.7 vs 7.4 h). In age group 1, the incidence of adverse events (AEs) was comparable between liposomal bupivacaine (61% [ 19/31] ) and bupivacaine HCl (73% [ 22/30 ]). In age group 2, 100% (5/5) and 31% (9/29) of patients undergoing spine and cardiac surgery experienced AEs, respectively. AEs were generally mild or moderate, with no discontinuations due to AEs or deaths. Conclusions: Plasma bupivacaine levels following local infiltration with liposomal bupivacaine remained below the toxic threshold in adults (~2000-4000 ng/mL) across age groups and procedures. AEs were mild to moderate, supporting the safety of liposomal bupivacaine in pediatric patients undergoing spine or cardiac surgery.
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    A phase I study of the anaplastic lymphoma kinase inhibitor ceritinib in combination with gemcitabine-based chemotherapy in patients with advanced solid tumors
    (Wiley, 2021) Fountzilas, Christos; Adjei, Alex; Opyrchal, Mateusz; Evans, Rachel; Ghasemi, Mohammad; Attwood, Kristopher; Groman, Adrienne; Bshara, Wiam; Goey, Andrew; Wilton, John; Ma, Wen Wee; Iyer, Renuka; Medicine, School of Medicine
    In this phase I, dose-escalation study, we sought to determine the maximum tolerated dose (MTD) of the anaplastic lymphoma kinase/c-ROS oncogene 1 receptor (ALK/ROS1) inhibitor ceritinib in combination with gemcitabine-based chemotherapy in patients with advanced solid tumors. Secondary objectives were characterization of the safety profile, pharmacokinetics and preliminary efficacy of these combinations, and identification of potential biomarkers of efficacy. Ceritinib was combined with gemcitabine (Arm 1), gemcitabine/nab-paclitaxel (Arm 2) or gemcitabine/cisplatin (Arm 3). Drug concentrations in plasma were measured by tandem mass spectrometric detection (LC-MS/MS). We analyzed archival tumor tissue for ALK, ROS1, hepatocyte growth factor receptor (c-MET) and c-Jun N-terminal kinase (JNK) expression by immunohistochemistry. Arm 2 closed early secondary to toxicity. Twenty-one patients were evaluable for dose-limiting toxicity (DLT). There was one DLT in Arm 1 (grade 3 ALT increase) and three DLTs in Arm 3 (grade 3 acute renal failure, grade 3 thrombocytopenia, grade 3 dyspnea). The MTD of ceritinib was determined to be 600 mg (Arm 1) and 450 mg orally daily (Arm 3). Main toxicities were hematologic, constitutional and gastrointestinal as expected by the chemotherapy backbone. The apparent clearance for ceritinib decreased substantially after repeated dosing; cisplatin did not significantly affect the pharmacokinetics of ceritinib. The overall response rate was 20%; the median progression-free survival was 4.8 months. Three out of five response-evaluable cholangiocarcinoma patients had clinical benefit. Increased expression of c-MET was associated with a lack of clinical benefit. Ceritinib in combination with gemcitabine and gemcitabine/cisplatin has a manageable toxicity profile. Further development of this strategy in tumors with ALK or ROS1 fusions is warranted.
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    Application of a single-objective, hybrid genetic algorithm approach to pharmacokinetic model building
    (Springer, 2012) Sherer, Eric A.; Sale, Mark E.; Pollock, Bruce G.; Belani, Chandra P.; Egorin, Merrill J.; Ivy, Percy S.; Lieberman, Jeffrey A.; Manuck, Stephen B.; Marder, Stephen R.; Muldoon, Matthew F.; Scher, Howard I.; Solit, David B.; Bies, Robert R.; Medicine, School of Medicine
    A limitation in traditional stepwise population pharmacokinetic model building is the difficulty in handling interactions between model components. To address this issue, a method was previously introduced which couples NONMEM parameter estimation and model fitness evaluation to a single-objective, hybrid genetic algorithm for global optimization of the model structure. In this study, the generalizability of this approach for pharmacokinetic model building is evaluated by comparing (1) correct and spurious covariate relationships in a simulated dataset resulting from automated stepwise covariate modeling, Lasso methods, and single-objective hybrid genetic algorithm approaches to covariate identification and (2) information criteria values, model structures, convergence, and model parameter values resulting from manual stepwise versus single-objective, hybrid genetic algorithm approaches to model building for seven compounds. Both manual stepwise and single-objective, hybrid genetic algorithm approaches to model building were applied, blinded to the results of the other approach, for selection of the compartment structure as well as inclusion and model form of inter-individual and inter-occasion variability, residual error, and covariates from a common set of model options. For the simulated dataset, stepwise covariate modeling identified three of four true covariates and two spurious covariates; Lasso identified two of four true and 0 spurious covariates; and the single-objective, hybrid genetic algorithm identified three of four true covariates and one spurious covariate. For the clinical datasets, the Akaike information criterion was a median of 22.3 points lower (range of 470.5 point decrease to 0.1 point decrease) for the best single-objective hybrid genetic-algorithm candidate model versus the final manual stepwise model: the Akaike information criterion was lower by greater than 10 points for four compounds and differed by less than 10 points for three compounds. The root mean squared error and absolute mean prediction error of the best single-objective hybrid genetic algorithm candidates were a median of 0.2 points higher (range of 38.9 point decrease to 27.3 point increase) and 0.02 points lower (range of 0.98 point decrease to 0.74 point increase), respectively, than that of the final stepwise models. In addition, the best single-objective, hybrid genetic algorithm candidate models had successful convergence and covariance steps for each compound, used the same compartment structure as the manual stepwise approach for 6 of 7 (86 %) compounds, and identified 54 % (7 of 13) of covariates included by the manual stepwise approach and 16 covariate relationships not included by manual stepwise models. The model parameter values between the final manual stepwise and best single-objective, hybrid genetic algorithm models differed by a median of 26.7 % (q₁ = 4.9 % and q₃ = 57.1 %). Finally, the single-objective, hybrid genetic algorithm approach was able to identify models capable of estimating absorption rate parameters for four compounds that the manual stepwise approach did not identify. The single-objective, hybrid genetic algorithm represents a general pharmacokinetic model building methodology whose ability to rapidly search the feasible solution space leads to nearly equivalent or superior model fits to pharmacokinetic data.
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    Characterization of hepatic enzyme activity in older adults with dementia: potential impact on personalizing pharmacotherapy
    (Dove Medical Press, 2015) Campbell, Noll L.; Skaar, Todd C.; Perkins, Anthony J.; Gao, Sujuan; Li, Lang; Khan, Babar A.; Boustani, Malaz A.; Department of Medicine, IU School of Medicine
    OBJECTIVE: To determine the frequency of pharmacogenomic variants and concurrent medications that may alter the efficacy and tolerability of acetylcholinesterase inhibitors (AChEIs). MATERIALS AND METHODS: A multisite cross-sectional study was carried out across four memory care practices in the greater Indianapolis area. Participants were adults aged 65 years and older with a diagnosis of probable or possible Alzheimer's disease (AD) (n=105). Blood samples and self-reported medication data were collected. Since two of the three AChEIs are metabolized by cytochrome P450 (CYP)-2D6, we determined the frequency of functional genetic variants in the CYP2D6 gene and calculated their predicted CYP2D6-activity scores. Concurrent medication data were collected from self-reported medication surveys, and their predicted effect on the pharmacokinetics of AChEIs was determined based on their known effects on CYP2D6 and CYP3A4/5 enzyme activities. RESULTS: Among the 105 subjects enrolled, 72% were female and 36% were African American. Subjects had a mean age of 79.6 years. The population used a mean of eight medications per day (prescription and nonprescription). The CYP2D6 activity score frequencies were 0 (3.8%), 0.5 (4.8%), 1.0 (36.2%), 1.5-2.0 (51.4%), and >2.0 (3.8%). Nineteen subjects (18.1%) used a medication considered a strong or moderate inhibitor of CYP2D6, and eight subjects (7.6%) used a medication considered a strong or moderate inhibitor of CYP3A4/5. In total, 28.6% of the study population was predicted to have reduced activity of the CYP2D6 or CYP3A4/5 enzymes due to either genetic variants or concomitant medications. CONCLUSION: Both pharmacogenetic variants and concurrent drug therapies that are predicted to alter the pharmacokinetics of AChEIs should be evaluated in older adults with AD. Pharmacogenetic and drug-interaction data may help personalize AD therapy and increase adherence by improving tolerability.
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    Characterization of Maternal and Fetal CYP3A-Mediated Progesterone Metabolism
    (Taylor & Francis, 2017-10) Quinney, Sara K.; Benjamin, Tara D.; Zheng, Xiaomei; Patil, Avinash; Obstetrics and Gynecology, School of Medicine
    INTRODUCTION: Progesterone is critical for maintaining pregnancy and onset of labor. We evaluated CYP450-mediated progesterone meta-bolism, specifically the contribution of CYP3A isoforms. MATERIALS AND METHODS: In vitro progesterone metabolism was characterized in human liver microsomes (HLMs) with and without selective cytochrome P450 inhibitors and in recombinant CYP3A4, CYP3A5, and CYP3A7. 6β-hydroxyprogesterone (6β-OHP) and 16α-hydroxyprogesterone (16α-OHP) metabolites were quantified by HPLC/UV and fit to the Michaelis-Menten equation to determine Km and Vmax. The effect of CYP3A5 expression on progesterone clearance was determined by in vitro in vivo extrapolation. RESULTS: Ketoconazole inhibited formation of both 6β-OHP and 16α-OHP more than 95%. 6β-OHP and 16α-OHP were both produced by CYP3A4 (2.3 and 1.3 µL/min/pmol, respectively) to a greater extent than by CYP3A5 (0.09 and 0.003 µL/min/pmol) and CYP3A7 (0.004 and 0.003 µL/min/pmol). CONCLUSIONS: Maternal clearance of progesterone by hepatic CYP450's is driven primarily by CYP3A4, with limited contributions from CYP3A5 and CYP3A7.
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    Chiral Plasma Pharmacokinetics and Urinary Excretion of Bupropion and Metabolites in Healthy Volunteers
    (ASPET, 2016-08) Masters, Andrea R.; Gufford, Brandon T.; Lu, Jessica Bo Li; Metzger, Ingrid F.; Jones, David R.; Desta, Zeruesenay; Medicine, School of Medicine
    Bupropion, widely used as an antidepressant and smoking cessation aid, undergoes complex metabolism to yield numerous metabolites with unique disposition, effect, and drug–drug interactions (DDIs) in humans. The stereoselective plasma and urinary pharmacokinetics of bupropion and its metabolites were evaluated to understand their potential contributions to bupropion effects. Healthy human volunteers (n = 15) were administered a single oral dose of racemic bupropion (100 mg), which was followed by collection of plasma and urine samples and determination of bupropion and metabolite concentrations using novel liquid chromatography–tandem mass spectrometry assays. Time-dependent, elimination rate–limited, stereoselective pharmacokinetics were observed for all bupropion metabolites. Area under the plasma concentration-time curve from zero to infinity ratios were on average approximately 65, 6, 6, and 4 and Cmax ratios were approximately 35, 6, 3, and 0.5 for (2R,3R)-/(2S,3S)-hydroxybupropion, R-/S-bupropion, (1S,2R)-/(1R,2S)-erythrohydrobupropion, and (1R,2R)-/(1S,2S)-threohydrobupropion, respectively. The R-/S-bupropion and (1R,2R)-/(1S,2S)-threohydrobupropion ratios are likely indicative of higher presystemic metabolism of S- versus R-bupropion by carbonyl reductases. Interestingly, the apparent renal clearance of (2S,3S)-hydroxybupropion was almost 10-fold higher than that of (2R,3R)-hydroxybupropion. The prediction of steady-state pharmacokinetics demonstrated differential stereospecific accumulation [partial area under the plasma concentration-time curve after the final simulated bupropion dose (300–312 hours) from 185 to 37,447 nM⋅h] and elimination [terminal half-life of approximately 7–46 hours] of bupropion metabolites, which may explain observed stereoselective differences in bupropion effect and DDI risk with CYP2D6 at steady state. Further elucidation of bupropion and metabolite disposition suggests that bupropion is not a reliable in vivo marker of CYP2B6 activity. In summary, to our knowledge, this is the first comprehensive report to provide novel insight into mechanisms underlying bupropion disposition by detailing the stereoselective pharmacokinetics of individual bupropion metabolites, which will enhance clinical understanding of bupropion’s effects and DDIs with CYP2D6.
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    Drug Interactions Affecting Oral Anticoagulant Use
    (American Heart Association, 2022) Mar, Philip L.; Gopinathannair, Rakesh; Gengler, Brooke E.; Chung, Mina K.; Perez, Arturo; Dukes, Jonathan; Ezekowitz, Michael D.; Lakkireddy, Dhanunjaya; Lip, Gregory Y. H.; Miletello, Mike; Noseworthy, Peter A.; Reiffel, James; Tisdale, James E.; Olshansky, Brian; American Heart Association Electrocardiography & Arrhythmias Committee of the Council of Clinical Cardiology; Medicine, School of Medicine
    Oral anticoagulants (OAC) are medications commonly used in patients with atrial fibrillation and other cardiovascular conditions. Both warfarin and direct oral anticoagulants (DOAC) are susceptible to drug-drug interactions (DDI). DDI are an important cause of adverse drug reactions and exact a large toll on the healthcare system. DDI for warfarin mainly involve moderate to strong inhibitors / inducers of cytochrome P450 (CYP) 2C9, which is responsible for the elimination of the more potent S-isomer of warfarin. However, inhibitor / inducers of CYP3A4 and CYP1A2 may also cause DDI with warfarin. Recognition of these precipitating agents along with increased frequency of monitoring when these agents are initiated or discontinued will minimize the impact of warfarin DDI. DOAC DDI are mainly affected by medications strongly affecting the permeability glycoprotein (P-gp), and to a lesser extent, strong CYP3A4 inhibitors / inducers. Dabigatran and edoxaban are affected by P-gp modulation. Strong inducers of CYP3A4 or P-gp should be avoided in all patients taking DOAC unless previously proven to be otherwise safe. Simultaneous strong CYP3A4 and P-gp inhibitors should be avoided in patients taking apixaban and rivaroxaban. Concomitant antiplatelet / anticoagulant use confers additive risk for bleeding, but their combination is unavoidable in many cases. Minimizing duration of concomitant anticoagulant/antiplatelet therapy as indicated by evidence-based clinical guidelines is the best way to reduce the risk of bleeding.
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    Effects of oxycodone pharmacogenetics on postoperative analgesia and related clinical outcomes in children: a pilot prospective study
    (Taylor & Francis, 2023) Aruldhas, Blessed W.; Quinney, Sara K.; Packiasabapathy, Senthil; Overholser, Brian R.; Raymond, Olivia; Sivam, Sahana; Sivam, Inesh; Velu, Sanjana; Montelibano, Antoinette; Sadhasivam, Senthilkumar; Medicine, School of Medicine
    Background: Variability in the pharmacokinetics and pharmacodynamics of oxycodone in children undergoing surgery could be due to genetic polymorphisms. Materials & methods: The authors studied the association between clinical outcomes and pharmacogenes in children undergoing major surgery. A total of 89 children (35 undergoing pectus excavatum repair and 54 undergoing spinal fusion) were recruited. Results: OPRM1 SNP rs6902403 showed an association with maximum pain score and total morphine equivalent dose (p < 0.05). Other polymorphisms in OPRM1 SNP, PXR, COMT and ABCB1 were also shown to be associated with average morphine equivalent dose, length of hospital stay and maximum surgical pain (p < 0.05). Conclusion: This study demonstrates novel associations between the above pharmacogenes and oxycodone's pharmacokinetics as well as postoperative outcomes in children.
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    Escitalopram in Adolescents with Generalized Anxiety Disorder: A Double-Blind, Randomized, Placebo-Controlled Study
    (Physicians Postgraduate Press, 2020-08) Strawn, Jeffrey R.; Mills, Jeffrey A.; Schroeder, Heidi; Mossman, Sarah A.; Varney, Sara T.; Ramsey, Laura B.; Poweleit, Ethan; Desta, Zeruesenay; Cecil, Kim; DelBello, Melissa P.; Medicine, School of Medicine
    Background: Selective serotonin reuptake inhibitors (SSRIs) are commonly used to treat pediatric anxiety disorders, including generalized anxiety disorder (GAD); however, their efficacy and tolerability are difficult to predict. This study evaluated the efficacy and tolerability of escitalopram in adolescents with GAD (DSM-IV-TR) and the impact of variants in HTR2A and serotonin transporter (SLC6A4) genes and cytochrome P450 2C19 (CYP2C19) phenotypes on response as well as CYP2C19 phenotype on escitalopram pharmacokinetics from February 2015 through November 2018. Methods: Patients were treated with escitalopram (forced titration to 15 mg/d, then flexible titration to 20 mg/d) (n = 26, mean ± SD age: 14.8 ± 1.7 years) or placebo (n = 25, mean ± SD age: 14.9 ± 1.6 years) for 8 weeks. Outcomes were the change in scores on the Pediatric Anxiety Rating Scale (PARS) and Clinical Global Impressions (CGI) scales as well as vital signs and adverse events. Plasma escitalopram and desmethylcitalopram area under the curve during 24 hours (AUC0-24) and maximum concentration (Cmax) were determined and compared across CYP2C19 phenotypes. Results: Escitalopram was superior to placebo for mean ± SD baseline-to-endpoint change in PARS (-8.65 ± 1.3 vs -3.52 ± 1.1, P = .005) and CGI scores, and increasing CYP2C19 metabolism was associated with decreases in escitalopram Cmax (P = .07) and AUC0-24 (P < .05). Vital signs, corrected QT interval, and adverse events were similar in patients who received escitalopram and placebo. Conclusions: Escitalopram reduces anxiety symptoms, and pharmacogenetics variables influence the trajectory and magnitude of improvement. Variation in CYP2C19 metabolism accounts for significant differences in escitalopram pharmacokinetics, raising the possibility that CYP2C19 phenotype should be considered when prescribing escitalopram.