A New Avenue for Enhanced Treatment of Hyperuricemia and Oxidative Stress: Design, Synthesis and Biological Evaluation of Some Novel Mutual Prodrugs Involving Febuxostat Conjugated with Different Antioxidants.

Febuxostat (FEB) is the first non-purine xanthine oxidase inhibitor (XOI) used for the treatment of hyperuricemia and gout. The oxidative stress induced by reactive oxygen species (ROS) which accompany purine metabolism by XO, could contribute to cellular damage and several pathological conditions. In this view, the present work addresses the evaluation of combining the hypouricemic effect of FEB and the free radical scavenging potential of various natural antioxidants in a single chemical entity by implementing the "mutual prodrug" strategy. Accordingly, a series of five ester prodrugs containing FEB together with different naturally occurring antioxidants namely, thioctic acid (4), thymol (5), menthol (6), vanillin (7), and guaiacol (8) was synthesized. Prominently, all the chemically conjugated prodrugs (4 - 8) revealed an obvious increase in the hypouricemic and antioxidant potentials when compared with their corresponding promoieties and physical mixtures. Moreover, they showed a potential protective effect against CCl4-induced hepatotoxicity and oxidative stress, together with no cytotoxicity on normal breast cells (MCF10A). Furthermore, the in vitro chemical and enzymatic stability studies of the prodrugs (4 - 8) using a developed HPLC method, verified their stability in different pHs, and rapid hydrolysis in rabbit plasma and liver homogenate to their parent metabolites. Moreover, the prodrugs (4 - 8) showed higher lipophilicity and lower aqueous solubility when compared to the parent drugs. Finally, the obtained merits from the implementation of the mutual prodrug strategy would encourage further application in the development of promising candidates with high therapeutic efficacy and improved safety profiles.

Towards the Development of Dual Hypouricemic and Anti-inflammatory Candidates: Design, Synthesis, Stability Studies and Biological Evaluation of Some Mutual Ester Prodrugs of Febuxostat-NSAIDs.

Treatment of gout involves two basic approaches: reducing the serum uric acid mainly by xanthine oxidase inhibitors (XOIs) and alleviating the intensity of the accompanying acute arthritic inflammation using non-steroidal anti-inflammatory drugs (NSAIDs). Febuxostat (FEB) is the first non-purine XOI approved for the treatment of hyperuricemia and gout. The present study aims at combining the hypouricemic effect of FEB and the anti-inflammatory (AI) properties of NSAIDs in a single entity by adopting the "mutual prodrug" approach. Accordingly, a series of seven ester prodrugs comprising basically FEB together with different NSAIDs namely, diclofenac (4), ibuprofen (5), ketoprofen (6), indomethacin (7), naproxen (8), ketorolac (9) and etodolac (10) was synthesized. All the investigated seven prodrugs (4-10) were equipotent or even superior to their corresponding parent drugs in the hypouricemic and AI activities, together with a gastrointestinal (GI) safety profile. Among this series, the prodrug FEB-DIC (4) showed excellent dual in vivo hypouricemic and anti-inflammatory activity (43.60 % and 15.96 %, respectively) when compared to the parent drugs FEB and diclofenac (36.82 % and 12.10 %, respectively) and its physical mixture (37.28 % and 12.41 %, respectively). Investigation of the in vitro chemical stability and hydrolysis of the prodrug (4) in aqueous and biological samples using a developed HPLC method confirmed its stability in various pHs, whereas rapid hydrolysis to the parent drugs in liver homogenate and human plasma was proven. Finally, it is concluded that the mutual prodrug approach could be successfully used in drug design and development for overcoming undesirable difficulties without losing the desired activities of the parent drugs.

Medical students' perceptions, experiences, and barriers towards research implementation at the faculty of medicine, Tanta university.

BACKGROUND: Research is essential for advancing medical knowledge and improving patient care. However, research capacity and output are low in low- and middle-income countries due to various challenges, including a lack of research training among medical students. Integrating research training into undergraduate medical curricula can help address this issue. METHODS: A cross-sectional study was conducted between December 2022 and March 2023 among 462 undergraduate medical students at Tanta University, Egypt to assess their knowledge, attitudes, and perceived barriers toward conducting research. Data were collected using a self-administered questionnaire and analyzed using SPSS. RESULTS: Nearly half (49.8%) of the students had an acceptable level of knowledge about research concepts while over two-thirds (66.2%) had a positive attitude. The most common barriers were lack of funding, time, and training in research methods. Previous research training was reported by 66.7% of students, but less than half had participated in or presented research. Students in the competency-based program had significantly higher knowledge and more positive attitudes than those in the mainstream program. Knowledge level was positively correlated with attitude. CONCLUSION: While attitudes were generally positive, improvements are needed in research training and opportunities among undergraduate medical students at Tanta University to help address low research capacity challenges in low- and middle-income countries. Integration of formal research training into the curriculum may help increase knowledge and participation in research.

Effect of CYP2C19 genetic variants on bleeding and major adverse cardiovascular events in a cohort of Arab patients undergoing percutaneous coronary intervention and stent implantation.

INTRODUCTION: One-third of patients have clopidogrel resistance that may lead to major adverse cardiac events (MACEs). By contrast, it was found that some clopidogrel-treated patients have hyperresponsive platelets that are associated with higher bleeding risk. Several studies have shown that polymorphisms in the gene encoding the CYP2C19 contribute to the variability in response to clopidogrel. Data on genetic and nongenetic factors affecting clopidogrel response in the Arab population are scarce. In this prospective cohort study, we sought to assess the association between the increased function allele (CYP2C19*17) and bleeding events, and validate the effect of the CYP2C19 genetic variants and nongenetic factors on the incidence of MACEs. METHODS: Blood samples were collected from patients that were undergoing percutaneous coronary intervention and receiving clopidogrel at the Heart Hospital, a specialist tertiary hospital in Doha, Qatar. Patients were followed for 12 months. Genotyping was performed for CYP2C19*2, *3, and *17 using TaqMan assays. RESULTS: In 254 patients, the minor allele frequencies were 0.13, 0.004, and 0.21 for *2, *3, and *17, respectively. Over a 12-month follow-up period, there were 21 bleeding events (8.5 events/100 patient-year). CYP2C19*17 carriers were found to be associated with increased risk of bleeding (OR, 21.6; 95% CI, 4.8-96.8; P < 0.0001). CYP2C19*2 or *3 carriers were found to be associated with increased risk of baseline and incident MACE combined (OR, 8.4; 95% CI, 3.2-23.9; P < 0.0001). CONCLUSION: This study showed a significant association between CYP2C19*17 allele and the increased risk of bleeding, and CYP2C19*2 or *3 with MACE outcomes.

The Use of an Inflatable Adhesive External Compression Device for Maintenance of Hemostasis following Angiography in Children.

PURPOSE: To assess the safety and efficacy of the posthemostasis use of an inflatable adhesive external compression device (SafeGuard) following angiography in children performed under general anesthesia. MATERIALS AND METHODS: Medical records of 74 children (43 females) with a mean age of 8.9 years (range, 0.4-18.0 years) and mean weight of 44.0 kg (range, 7.3-115.7 kg) in whom an inflatable adhesive external compression device was used for maintaining hemostasis following angiography under general anesthesia were retrospectively reviewed. After establishing hemostasis with manual compression, the device was applied and inflated over the arteriotomy. The patients were assessed for access-related adverse events in the recovery unit and during postprocedural follow-up. RESULTS: The inflatable adhesive external compression device was utilized to maintain hemostasis following 181 angiography procedures. The mean length of the procedure was 396 minutes. The common femoral artery (n = 170, 93.9%) was the most common access, using 4-5-F vascular sheath (n = 118, 65.2%) or 3-5-F sheathless (n = 8, 12.7%) catheters. The mean time to deflation was 93 minutes. There were no adverse events other than minor bleeding from the arteriotomy after deflation (n = 2, 1.1%) and early deflation of the device because of pain (n = 1, <1%). Follow-up ultrasonography (n = 109 procedures, 60.2% at a mean follow-up of 2.2 years) demonstrated patency of the access artery. CONCLUSIONS: The use of an inflatable adhesive external compression device following angiography in children to maintain hemostasis during the emergence phase of anesthesia and recovery period is safe and effective. The use of this simple device may reduce the need for postprocedural sedation and facilitate early discharge.

Effects of vitamin C, vitamin E, selenium, zinc, or their nanoparticles on camel epididymal spermatozoa stored at 4 °C.

This study determined the effects of antioxidant supplementation and storage time at cool temperatures on the characteristics of epididymal camel spermatozoa. Camel testes were collected at the abattoir after animal slaughtering and kept at 4 °C during transportation and until processing (max 6 h). Spermatozoa were retrieved and diluted with SHOTOR extender, split in aliquots, supplemented with the following antioxidants: 200 µm/mL vitamin E, 1.0 g/L vitamin C, 1 µg/mL selenium nanoparticles, 50 µg/mL zinc nanoparticles, 2 µg/mL sodium selenite, and 100 µg/mL zinc sulfate, and stored at 4 °C for 2, 48, 96, and 144 h. The storage time significantly affected (P < 0.05) the sperms' motility and livability, the sperms' membrane integrity, and the percentages of cytoplasmic droplets as well as the percentage of morphologically normal spermatozoa. Epididymal sperm characteristics (progressive motility, livability, membrane integrity, and abnormalities) were significantly improved (P < 0.05) when the spermatozoa were diluted with antioxidants as compared with the control group, and the best additives were identified as nano-selenium, sodium selenite, nano-zinc, and zinc sulfate. In conclusion, adding nano-sized minerals or inorganic trace elements and vitamins maintained the progressive motility, livability, and membrane integrity, and decreased abnormalities and cytoplasmic droplet percentages of epididymal camel spermatozoa stored at 4 °C up to 144 h.

The effect of genetic and nongenetic factors on warfarin dose variability in Qatari population.

The objective of this study is to estimate the prevalence of VKORC1, CYP2C9, and CYP4F2 genetic variants and their contribution to warfarin dose variability in Qataris. One hundred and fifty warfarin-treated Qatari patients on a stable dose and with a therapeutic INR for at least three consecutive clinic visits were recruited. Saliva samples were collected using Oragene DNA self-collection kit, followed by DNA purification and genotyping via TaqMan Real-Time-PCR assay. The population was stratified into derivation and validation cohorts for the dosing model. The minor allele frequency (MAF) of VKORC1 (-1639G>A) was A (0.47), while the MAF's for the CYP2C9*2 and *3 and CYP4F2*3 were T (0.12), C (0.04) and T (0.43), respectively. Carriers of at least one CYP2C9 decreased function allele (*2 or *3) required lower median (IQR) warfarin doses compared to noncarriers [24.5 (14.5) mg/week vs. 35 (21) mg/week, p < 0.001]. Similarly, carriers of each additional copy of (A) variant in VKORC1 (-1639G>A) led to reduction in warfarin dose requirement compared to noncarriers [21(7.5) vs. 31.5(18.7) vs. 43.7(15), p < 0.0001]. CYP4F2*3 polymorphism on the other hand was not associated with warfarin dose. Multivariate analysis on the derivation cohort (n = 104) showed that a dosing model consisting of hypertension (HTN), heart failure (HF), VKORC1 (-1639G>A), CYP2C9*2 & *3, and smoking could explain 39.2% of warfarin dose variability in Qataris (P < 0.001). In the validation cohort (n = 45), correlation between predicted and actual warfarin doses was moderate (Spearman's rho correlation coefficient = 0.711, p < 0.001). This study concluded that VKORC1 (-1639G>A), CYP2C9*2 & *3 are the most significant predictors of warfarin dose along with HTN, HF and smoking.

Sublingual vs vaginal misoprostol for completion of first trimester missed abortion: a randomised controlled trial.

OBJECTIVE: The study aimed to compare the efficacy and safety of sublingual and vaginal misoprostol for termination of pregnancy in women with first trimester missed abortion. METHODS: A single-blind, parallel group, randomised clinical trial (ClinicalTrials.gov NCT02686840) was conducted in a university hospital between 1 February 2016 and 31 January 2017. All women who presented with first trimester missed abortion were invited to participate in the study and were randomised to one of two groups: one group received sublingual misoprostol in three doses of 800 µg every 4 h, while a second group received vaginal misoprostol in the same dosage regimen. The primary outcome of the study was the rate of complete abortion within 7 days after initiation of treatment. RESULTS: The study included 200 women (100 in each arm). By day 7, successful complete abortion was significantly more frequent in the sublingual misoprostol group (71.4%) than in the vaginal misoprostol group (51.5%) (p = .006). By day 30, the rate of complete abortion was higher in the sublingual misoprostol group (90.6%) than in the vaginal misoprostol group (83.9%), but with no statistically significant difference (p = .164). The mean length of the induction-expulsion interval in the sublingual misoprostol group was significantly shorter compared with the vaginal misoprostol group (12.3 ± 3.1 h vs 16.4 ± 4.2 h, respectively; p = .001) and the sublingual misoprostol group had a smaller drop in haemoglobin level (p = .001). The side effects of misoprostol were significantly more frequent in the sublingual group compared with the vaginal group. CONCLUSION: Sublingual misoprostol is more effective than vaginal misoprostol in completing first trimester missed abortion, with a shorter induction-expulsion time. Sublingual misoprostol is, however, associated with more side effects, such as unpleasant taste, gastrointestinal symptoms and fever, compared with vaginal misoprostol.

Pharmacogenetic and clinical predictors of response to clopidogrel plus aspirin after acute coronary syndrome in Egyptians.

OBJECTIVES: Dual antiplatelet therapy (DAPT) with aspirin and clopidogrel reduces the risk for recurrent cardiovascular events after acute coronary syndrome (ACS). However, there is significant variation in response to DAPT that may be influenced by both genetic and nongenetic factors. This study aimed to assess the effect of genetic polymorphisms in PON-1, PEAR-1, P2Y12, CES1, and CYP2C19, along with clinical, demographic, and social factors, on variation in response to DAPT in Egyptians. PARTICIPANTS AND METHODS: This study included 230 Egyptians treated with clopidogrel 75 mg/day and aspirin 81 mg/day for at least 12 months following their first ACS. Simple and multivariable logistic regression analyses were carried out to identify factors associated with major adverse cardiovascular events (MACE), defined as the occurrence of recurrent ACS, ischemic stroke, stent-related revascularization, or death, in clopidogrel-treated participants. RESULTS: Using multivariable logistic regression analysis, the CYP2C19*2 polymorphism was the only genetic predictor of MACE [odds ratio (OR): 2.23, 95% confidence interval (CI): 1.15-4.33, P=0.01]. In addition, proton pump inhibitor use (OR: 4.77, 95% CI: 1.47-15.54, P=0.009) and diabetes (OR: 1.83, 95% CI: 1.03-3.26, P=0.03) were associated with higher cardiovascular risk, whereas statin use was associated with lower risk (OR: 0.43, 95% CI: 0.25-0.76, P=0.003). The contribution of these four genetic and nongenetic factors explained 19% of the variability in risk for MACE in Egyptians treated with DAPT. CONCLUSION: These results highlight that CYP2C19*2, along with diabetes, and use of proton pump inhibitor and statin are important factors jointly associated with variability in clinical response to DAPT following ACS in Egyptians.

Targeted sequencing identifies a missense variant in the BEST3 gene associated with antihypertensive response to hydrochlorothiazide.

Chromosome 12q15 was identified in Genetic Epidemiology of Response Assessment (GERA) and replicated in Pharmacogenomic Evaluation of Antihypertensive Responses (PEAR) for its association with blood pressure (BP) response to hydrochlorothiazide (HCTZ). However, the functional variant is unknown and we aimed to identify the likely functional variants through targeted sequencing. The chromosome 12q15 region was sequenced in 397 best and worst responders to HCTZ in PEAR (N=199) and GERA (N=198) hypertensive study participants. Logistic regression was used for the association analysis adjusting for age, sex, race, and principal components 1 and 2. For validation, the significant single nucleotide polymorphism was tested for association with the change in systolic (ΔSBP) and diastolic BP (ΔDBP) post-treatment in the entire PEAR (N=370) and GERA (N=570) cohorts. A novel missense polymorphism (G>A, Pro383Leu) in BEST3, rs61747221, was significantly associated with better HCTZ response (P=0.0021, odds ratio=2.05). It was validated in the entire cohort of PEAR (ΔSBP: P=0.021, ß=-1.60, ΔDBP: P=0.023, ß=-1.08) and GERA (ΔSBP: P=0.028, ß=-1.95, ΔDBP: P=0.032, ß=-1.28). BEST3 encodes the calcium sensitive chloride channel in the vascular smooth muscle implicated in the regulation of BP, especially in response to vasoconstrictors like angiotensin II. These results suggest that BEST3 is involved in the chronic BP lowering mechanism of thiazides and highlight its importance as a genetic predictor of the BP response to thiazide diuretics.

Matrix Metalloproteinase Polymorphisms in Patients with Floppy Mitral Valve/Mitral Valve Prolapse (FMV/MVP) and FMV/MVP Syndrome.

BACKGROUND: It has been suggested that collagen abnormalities of the mitral valve are present in patients with floppy mitral valve (FMV)/mitral valve prolapse (MVP). Genetic factors determining collagen synthesis and degradation have not been well defined in these patients. This study was undertaken to determine whether selective polymorphisms of matrix metalloproteinase-2 (MMP2) or transforming growth factor-ß (TGFß), with known or putative effects on collagen turnover, are more frequent in FMV/MVP. METHODS: Single nucleotide polymorphisms (SNPs) in select genes related to collagen turnover, including MMP2 rs2285053, MMP2 rs243865, TGFß1 rs1800469, and TGFß2 rs900, were determined in 98 patients with FMV/MVP who had severe mitral regurgitation and compared to 99 controls. RESULTS: MMP2 rs243865 was the only SNP significantly associated with FMV/MVP as compared to the control (odds ratio 2.07, 95% CI 1.23-3.50, p = 0.006). MMP2 rs228503 was the only SNP significantly associated with the FMV/MVP syndrome as compared to patients with FMV/MVP without the syndrome (odds ratio 2.41, 95% CI 1.08-5.40, p = 0.032). CONCLUSION: The frequency of certain MMP2 polymorphisms is higher in patients with the FMV/MVP syndrome and patients with FMV/MVP without the syndrome. The data suggest that a genetic predisposition that alters collagen turnover may play a role in the pathogenesis and development of FMV/MVP.

Genetic variants associated with warfarin dose in African-American individuals: a genome-wide association study.

BACKGROUND: VKORC1 and CYP2C9 are important contributors to warfarin dose variability, but explain less variability for individuals of African descent than for those of European or Asian descent. We aimed to identify additional variants contributing to warfarin dose requirements in African Americans. METHODS: We did a genome-wide association study of discovery and replication cohorts. Samples from African-American adults (aged ≥18 years) who were taking a stable maintenance dose of warfarin were obtained at International Warfarin Pharmacogenetics Consortium (IWPC) sites and the University of Alabama at Birmingham (Birmingham, AL, USA). Patients enrolled at IWPC sites but who were not used for discovery made up the independent replication cohort. All participants were genotyped. We did a stepwise conditional analysis, conditioning first for VKORC1 -1639G→A, followed by the composite genotype of CYP2C9*2 and CYP2C9*3. We prespecified a genome-wide significance threshold of p<5×10(-8) in the discovery cohort and p<0·0038 in the replication cohort. FINDINGS: The discovery cohort contained 533 participants and the replication cohort 432 participants. After the prespecified conditioning in the discovery cohort, we identified an association between a novel single nucleotide polymorphism in the CYP2C cluster on chromosome 10 (rs12777823) and warfarin dose requirement that reached genome-wide significance (p=1·51×10(-8)). This association was confirmed in the replication cohort (p=5·04×10(-5)); analysis of the two cohorts together produced a p value of 4·5×10(-12). Individuals heterozygous for the rs12777823 A allele need a dose reduction of 6·92 mg/week and those homozygous 9·34 mg/week. Regression analysis showed that the inclusion of rs12777823 significantly improves warfarin dose variability explained by the IWPC dosing algorithm (21% relative improvement). INTERPRETATION: A novel CYP2C single nucleotide polymorphism exerts a clinically relevant effect on warfarin dose in African Americans, independent of CYP2C9*2 and CYP2C9*3. Incorporation of this variant into pharmacogenetic dosing algorithms could improve warfarin dose prediction in this population. FUNDING: National Institutes of Health, American Heart Association, Howard Hughes Medical Institute, Wisconsin Network for Health Research, and the Wellcome Trust.

Artificial Intelligence: From Buzzword to Useful Tool in Clinical Pharmacology.

The advent of artificial intelligence (AI) in clinical pharmacology and drug development is akin to the dawning of a new era. Previously dismissed as merely technological hype, these approaches have emerged as promising tools in different domains, including health care, demonstrating their potential to empower clinical pharmacology decision making, revolutionize the drug development landscape, and advance patient care. Although challenges remain, the remarkable progress already made signals that the leap from hype to reality is well underway, and AI promises to offer clinical pharmacology new tools and possibilities for optimizing patient care is gradually coming to fruition. This review dives into the burgeoning world of AI and machine learning (ML), showcasing different applications of AI in clinical pharmacology and the impact of successful AI/ML implementation on drug development and/or regulatory decisions. This review also highlights recommendations for areas of opportunity in clinical pharmacology, including data analysis (e.g., handling large data sets, screening to identify important covariates, and optimizing patient population) and efficiencies (e.g., automation, translation, literature curation, and training). Realizing the benefits of AI in drug development and understanding its value will lead to the successful integration of AI tools in our clinical pharmacology and pharmacometrics armamentarium.

Artificial Intelligence for Quantitative Modeling in Drug Discovery and Development: An Innovation and Quality Consortium Perspective on Use Cases and Best Practices.

Recent breakthroughs in artificial intelligence (AI) and machine learning (ML) have ushered in a new era of possibilities across various scientific domains. One area where these advancements hold significant promise is model-informed drug discovery and development (MID3). To foster a wider adoption and acceptance of these advanced algorithms, the Innovation and Quality (IQ) Consortium initiated the AI/ML working group in 2021 with the aim of promoting their acceptance among the broader scientific community as well as by regulatory agencies. By drawing insights from workshops organized by the working group and attended by key stakeholders across the biopharma industry, academia, and regulatory agencies, this white paper provides a perspective from the IQ Consortium. The range of applications covered in this white paper encompass the following thematic topics: (i) AI/ML-enabled Analytics for Pharmacometrics and Quantitative Systems Pharmacology (QSP) Workflows; (ii) Explainable Artificial Intelligence and its Applications in Disease Progression Modeling; (iii) Natural Language Processing (NLP) in Quantitative Pharmacology Modeling; and (iv) AI/ML Utilization in Drug Discovery. Additionally, the paper offers a set of best practices to ensure an effective and responsible use of AI, including considering the context of use, explainability and generalizability of models, and having human-in-the-loop. We believe that embracing the transformative power of AI in quantitative modeling while adopting a set of good practices can unlock new opportunities for innovation, increase efficiency, and ultimately bring benefits to patients.

Clopidogrel and warfarin pharmacogenetic tests: what is the evidence for use in clinical practice?

PURPOSE OF REVIEW: To review the most promising genetic markers associated with the variability in the safety or efficacy of warfarin and clopidogrel and highlight the verification and validation initiatives for translating clopidogrel and warfarin pharmacogenetic tests to clinical practice. RECENT FINDINGS: Rapid advances in pharmacogenetics, continuous decrease in genotyping cost, development of point-of-care devices and the newly established clinical genotyping programs at several institutions hold the promise of individualizing clopidogrel and warfarin based on genotype. Guidelines have been established to assist clinicians in prescribing clopidogrel or warfarin dose based on genotype. However, the clinical utility of clopidogrel and warfarin is still limited. Accordingly, large randomized clinical trials are underway to define the role of clopidogrel and warfarin pharmacogenetics in clinical practice. SUMMARY: Pharmacogenetics has offered compelling evidence toward the individualization of clopidogrel and warfarin therapies. The rapid advances in technology make the clinical implementation of clopidogrel and warfarin pharmacogenetics possible. The clinical genotyping programs and the ongoing clinical trials will help in overcoming some of the barriers facing the clinical implementation of clopidogrel and warfarin pharmacogenetics.

Renal cell carcinoma presenting with upper gastrointestinal bleeding: A case report.

Renal cell carcinoma (RCC) is increasing in incidence as more cross sectional imaging is performed with approximately 20%-30% of cases presenting with metastasis at the time of diagnosis. Small bowel metastatic disease is rare, with RCC to the small bowel being exceptionally rare. We present a case report of metastatic RCC that initially presented as upper gastrointestinal bleeding at time of diagnosis. We also provide a brief discussion of small bowel metastatic RCC disease and literature review.

Cryoablation for Bone and Soft Tissue Lesions in Pediatric Patients: Complications and Preventive Measures.

PURPOSE: To evaluate complications associated with cryoablation in a pediatric population and review preventive measures to mitigate these complications. MATERIAL AND METHODS: Retrospective study including all the image guided cryoablations performed on pediatric population. Immediate and delayed complications were analyzed, and we identified the different protective measures used and the clinical outcomes from follow-up. Point estimates for the percentage of complications were calculated by maximum likelihood, and 95% confidence intervals for the true percentages were calculated using the Clopper-Pearson exact method. RESULTS: Eighty-seven ablations were performed on 68 patients (age range of 2-18 years, mean 12.4 years) for non-neoplastic (70%) and neoplastic (30%) lesions. The percentage of ablations resulting in complications was 18% (95% confidence interval (CI) 11% to 28%). Of these, 5% (95% CI 1% to 11%) were grade 3 complications, and 14% (95% CI 7% to 23%) were grade 2 complications. Thermal protection was performed in 27.6% of ablations (n = 24). The mean clinical follow-up duration was 348 days. CONCLUSION: Cryoablation in pediatric patients is relatively safe, with a major complication rate per ablation of 5%. Thermal protective measures can be considered to mitigate these complications.

Population Pharmacokinetic and Pharmacodynamic Modeling of Fesoterodine in Pediatric Patients with Neurogenic Detrusor Overactivity.

BACKGROUND AND OBJECTIVE: Fesoterodine is a muscarinic receptor antagonist approved for the treatment of overactive bladder (OAB) in adults and neurogenic detrusor overactivity (NDO) in pediatric patients. This work aimed to characterize the population pharmacokinetics of 5-hydroxymethyl tolterodine (5-HMT, the active metabolite of fesoterodine) and its pharmacokinetic/pharmacodynamic relationship in pediatric patients with OAB or NDO following administration of fesoterodine. METHODS: 5-HMT plasma concentrations from 142 participants of age ≥ 6 years were analyzed, and a nonlinear mixed-effects model was developed. Weight-based simulations of 5-HMT exposure and maximum cystometric capacity (MCC) were conducted using the final models. RESULTS: A one-compartment model with first-order absorption and a lag time, which included the effects of body weight, sex, cytochrome (CYP) 2D6 metabolizer status and fesoterodine formulation on pharmacokinetic parameters, best described the 5-HMT pharmacokinetics. An Emax model described the exposure-response relationship adequately. The median maximum concentration at steady state for pediatric patients weighing 25-35 kg and receiving 8 mg once daily (QD) was estimated to be 2.45 times greater than that in adults receiving 8 mg QD. Furthermore, simulation results showed dosing with fesoterodine 4 mg QD to pediatric patients weighing 25-35 kg and 8 mg QD to pediatric patients weighing >35 kg would achieve adequate exposure to demonstrate a clinically meaningful change from baseline (CFB) MCC. CONCLUSIONS: Population models were developed for 5-HMT and MCC in pediatric patients. Weight-based simulations indicated that 4 mg QD for pediatric patients weighing 25-35 kg and 8 mg QD for those weighing > 35 kg provided similar exposures to those in adults following 8 mg QD and a clinically meaningful CFB MCC. CLINICAL TRIAL NUMBERS: NCT00857896, NCT01557244.

Fesoterodine is a muscarinic receptor antagonist approved for the treatment of overactive bladder (OAB) in adults and neurogenic detrusor overactivity (NDO) in pediatric patients in the US. Population pharmacokinetic and pharmacokinetic/pharmacodynamic models were developed for 5-HMT based on data from two pediatric clinical trials that included 142 patients of age ≥ 6 years with OAB or NDO. Weight-based simulations of 5-HMT exposure and maximum cystometric capacity were conducted using the final models to examine the impact of covariates on 5-HMT exposure and the exposure­response profile. The results of these simulations indicate that 4 mg QD for pediatric patients weighing 25­35 kg and 8 mg QD for those weighing > 35 kg provide similar exposures to those in adults following 8 mg QD.

Fesoterodine treatment of pediatric patients with neurogenic detrusor overactivity: A 24-week, randomized, open-label, phase 3 study.

BACKGROUND: Neurogenic detrusor overactivity (NDO) can damage the upper urinary tract leading to chronic renal impairment. Antimuscarinic therapy is used to improve urinary incontinence and protect the upper urinary tract in patients with NDO. OBJECTIVE: This study investigated safety and efficacy of fesoterodine, a muscarinic receptor antagonist, in 6‒<18-year-old patients with NDO (NCT01557244). STUDY DESIGN: This open-label phase 3 study included 2 pediatric cohorts. Patients in Cohort 1 (bodyweight >25 kg) were randomized to fesoterodine 4 or 8 mg extended-release tablets or oxybutynin XL tablets administered over the 12-week active comparator-controlled phase. The safety extension phase evaluated fesoterodine 4 and 8 mg for a further 12 weeks, with patients in the oxybutynin arm allocated to fesoterodine 4 or 8 mg. Patients in Cohort 2 (bodyweight ≤25 kg) were randomized to fesoterodine 2 or 4 mg extended-release beads-in-capsule (BIC) administered over a 12-week efficacy phase and 12-week safety extension phase. Patients with stable neurologic disease and clinically or urodynamically proven NDO were included. The primary endpoint was change from baseline to Week 12 in maximum cystometric bladder capacity (MCC). Secondary efficacy endpoints included detrusor pressure at maximum bladder capacity, bladder volume at first involuntary detrusor contraction, bladder compliance, and incontinence episodes. Safety endpoints included adverse event incidence, and specific assessments of cognition, behavior and vision. The pharmacokinetics of 5-hydroxymethyl tolterodine (5-HMT; fesoterodine's active metabolite) was determined using population-pharmacokinetic analysis. RESULTS: In Cohort 1 (n = 124), fesoterodine 4 and 8 mg treatment resulted in significant increases from baseline in the primary endpoint of MCC at Week 12. In Cohort 2 (n = 57), fesoterodine 2 and 4 mg BIC treatment resulted in improvements in MCC from baseline. Fesoterodine 4 and 8 mg and fesoterodine 4 mg BIC led to improvements in some secondary efficacy endpoints. The most common treatment-related adverse reactions were gastrointestinal effects, such as dry mouth, which occurred more frequently with oxybutynin than fesoterodine. No detrimental effects on visual accommodation or acuity, or on cognitive function or behavior were observed. DISCUSSION: These safety and efficacy results are consistent with limited published data on fesoterodine treatment in pediatric populations with overactive bladder or NDO. Study limitations include the lack of placebo control and the small sample size, which limits the ability to make formal efficacy comparisons and detect rare adverse reactions. CONCLUSION: Fesoterodine has a favorable benefit-risk profile in 6‒<18-year-old patients with NDO and may represent an additional option for pediatric NDO treatment.

CYP2C9 promoter variable number tandem repeat polymorphism regulates mRNA expression in human livers.

CYP2C9 is involved in metabolism of nearly 25% of clinically used drugs. Coding region polymorphisms CYP2C9*2 and *3 contribute to interperson variability in drug dosage and clinical outcomes, whereas the role of a regulatory polymorphism remains uncertain. Measuring allelic RNA expression in 87 human liver samples, combined with genotyping, sequencing, and reporter gene assays, we identified a promoter variable number tandem repeat polymorphism (pVNTR) that fully accounted for allelic CYP2C9 mRNA expression differences. Present in three different variant forms [short (pVNTR-S), medium (pVNTR-M), and long (pVNTR-L)], only the pVNTR-S allele reduced the CYP2C9 mRNA level compared with the pVNTR-M (reference) allele. pVNTR-S is in linkage disequilibrium with *3, with linkage disequilibrium r(2) of 0.53 to 0.75 in different populations. In patients who were taking a maintenance dose of warfarin, the mean warfarin dose was associated with the copies of pVNTR-S (p = 0.0001). However, in multivariate regression models that included the CYP2C9*3, pVNTR-S was no longer a significant predictor of the warfarin dose (p = 0.60). These results indicate that although pVNTR-S reduced CYP2C9 mRNA expression, the in vivo effects of pVNTR-S on warfarin metabolism cannot be separated from the effects of *3. Therefore, it is not necessary to consider pVNTR-S as an additional biomarker for warfarin dosing. Larger clinical studies are needed to define whether the pVNTR-S has a minimal effect in vivo, or whether the effect attributed to *3 is really a combination of effects on expression by the pVNTR-S along with effects on catalytic activity from the nonsynonymous *3 variant.