Limited Sampling Strategies to Predict Ganciclovir Exposure after Valganciclovir Administration and to Reduce Monitoring Constraints in Renal Transplant Children

Valganciclovir, the ganciclovir prodrug, is an antiviral agent used to prevent cytomegalovirus infection in renal transplant children. Therapeutic drug monitoring is still necessary to ensure optimal therapeutic area under the concentration-time curve from 0 to 24 h (AUC0-24) of 40 to 60 μg·h/mL since valganciclovir presents a high pharmacokinetic variability. To calculate ganciclovir AUC0-24 with the trapezoidal method, 7 samples are needed. The objective of this study was to develop and validate a reliable and clinically applicable limited sampling strategy (LSS) for individualizing valganciclovir dose in renal transplant children. Rich pharmacokinetic data from ganciclovir plasmatic dosages measured in renal transplant children who received valganciclovir to prevent cytomegalovirus infection at Robert Debré University Hospital were collected retrospectively. Ganciclovir AUC0-24s were calculated using the trapezoidal method. The LSS was developed using a multilinear regression approach to predict AUC0-24. The patients included were divided into two groups for model development (50 patients) and validation (30 patients). A total of 80 patients were included between February 2005 and November 2018. Multilinear regression models were developed on 50 pharmacokinetic profiles (50 patients) and validated with an independent group of 43 pharmacokinetic profiles (30 patients). Regressions based on samples collected at T1h-T4h-T8h, T2h-T4h-T8h, or T1h-T2h-T8h presented the best AUC0-24 predictive performances with an average difference between reference and predicted AUC0-24 of -0.27, 0.34, and -0.40 μg·h/mL, respectively. In conclusion, valganciclovir dosage adaptation was required in children to achieve the target AUC0-24. Three LSS models using three pharmacokinetic blood samples instead of seven will be useful for individualizing valganciclovir prophylaxis in renal transplant children.

Simplified Dosing Regimens for Gentamicin in Neonatal Sepsis

Background: The effectiveness of antibiotics for the treatment of severe bacterial infections in newborns in resource-limited settings has been determined by empirical evidence. However, such an approach does not warrant optimal exposure to antibiotic agents, which are known to show different disposition characteristics in this population. Here we evaluate the rationale for a simplified regimen of gentamicin taking into account the effect of body size and organ maturation on pharmacokinetics. The analysis is supported by efficacy data from a series of clinical trials in this population.

Methods: A previously published pharmacokinetic model was used to simulate gentamicin concentration vs. time profiles in a virtual cohort of neonates. Model predictive performance was assessed by supplementary external validation procedures using therapeutic drug monitoring data collected in neonates and young infants with or without sepsis. Subsequently, clinical trial simulations were performed to characterize the exposure to intra-muscular gentamicin after a q.d. regimen. The selection of a simplified regimen was based on peak and trough drug levels during the course of treatment.

Results: In contrast to current World Health Organization guidelines, which recommend gentamicin doses between 5 and 7.5 mg/kg, our analysis shows that gentamicin can be used as a fixed dose regimen according to three weight-bands: 10 mg for patients with body weight <2.5 kg, 16 mg for patients with body weight between 2.5 and 4 kg, and 30 mg for those with body weight >4 kg.

Conclusion: The choice of the dose of an antibiotic must be supported by a strong scientific rationale, taking into account the differences in drug disposition in the target patient population. Our analysis reveals that a simplified regimen is feasible and could be used in resource-limited settings for the treatment of sepsis in neonates and young infants with sepsis aged 0–59 days.

Population pharmacokinetics of ceftazidime in critically ill children: impact of cystic fibrosis

BACKGROUND

Pharmacokinetics data on ceftazidime are sparse for the paediatric population, particularly for children with cystic fibrosis (CF) or severe infections.

OBJECTIVES

To characterize the population pharmacokinetics of ceftazidime in critically ill children, identify covariates that affect drug disposition and evaluate the current dosing regimens.

METHODS

The study was registered with Clinicaltrials.gov (NCT01344512). Children receiving ceftazidime were selected in 13 French hospitals. Plasma concentrations were determined by UPLC-MS/MS. Population pharmacokinetic analyses were performed using NONMEN software.

RESULTS

One hundred and eight patients, aged 28 days to 12 years, with CF (n = 32), haematology and/or oncology disorders (n = 47) or severe infection (n = 29) were included. Ceftazidime was administered by continuous or intermittent infusions; 271 samples were available for analysis. A two-compartment model with first-order elimination and allometric scaling was developed and covariate analysis showed that ceftazidime pharmacokinetics were also significantly affected by CLCR and CF. Ceftazidime clearance was 82% higher in CF than in non-CF patients. Monte Carlo simulations showed that the percentage of target attainment (PTA) for the target of T>MIC = 65% was (i) lower in CF than in non-CF children with intermittent infusions and (ii) higher with continuous than intermittent infusion in all children.

CONCLUSIONS

The population pharmacokinetics model for ceftazidime in children was influenced by body weight, CLCR and CF. A higher PTA was obtained with continuous versus intermittent infusions. Further studies should explore the benefits of continuous versus intermittent infusion of ceftazidime, including current versus increased doses in CF children.

FC13-11 - Effectiveness of mazindol in children with ADHD : open-label study

Mazindol is a central nervous system stimulant, which blocks reuptake of dopamine and norepinephrine. Mazindol (1–6 mg/d) has previously been studied in the treatment of excessive daytime sleepiness with relative therapeutic benefit. Our hypothesis suggests that mazindol may be effective for the treatment of Attention Deficit Hyperactivity Disorder symptoms.

Based on clinical assessments after oral administration of mazindol to 24 children (9–12 years) with ADHD (according to DSM-IVTR criteria), this open-label study evaluates the efficacy, safety and tolerability of mazindol (1 mg/d, 7 days). Safety evaluations included routine hematology, electrocardiograms, blood pressure, and pulse rate. Efficacy rating measurements included ADHD-RS score (primary outcome measure), CPRS-R:L, CGI-S and CGI-I (secondary outcome measures). This clinical trial reports data obtained from 21 boys (10 ± 1 years).

Based on primary outcome (ADHD-RS), change in ADHD-RS mean total score after one week of mazindol was −24.6 (p < 0.0001) ; greater than a 90% improvement from baseline. Change in CPRS-R:L (80 items) mean total score after one week of mazindol was −55.5 (p < 0.0001); CGI-S after one week of mazindol was -3,02 (p< 0.01). Adverse events were mild to moderate in severity and decreased appetite, weight loss, headache, and abdominal pain were most common (95%).

Changes in laboratory values, ECG, blood pressure, pulse rate and body weight were not clinically meaningful. Blood pressure and pulse rate were unchanged (p > 0.05) after one week of treatment.

This preliminary investigation suggests that mazindol is still a new well-tolerated and active psychostimulant for the treatment of ADHD in children.

Pharmacokinetics and safety of fluconazole and micafungin in neonates with systemic candidiasis: a randomized, open-label clinical trial

AIMS

The pharmacokinetics (PK) of fluconazole and micafungin differ in neonates compared with children and adults. Dosing instructions in product labels appear to be inconsistent with the emerging scientific evidence. Limited information is available on the safety profile of these agents in neonates. Our objective was to study the population PK and safety of both drugs, randomly administered in neonates with suspected or confirmed systemic candidiasis.

METHODS

Neonates were randomized 1:1 to fluconazole (loading dose 25 mg kg^-1 ; maintenance dose 12 mg kg^-1 day^-1 or 20 mg kg^-1 day^-1 , respectively, for infants <30 weeks or ≥30 weeks' corrected gestational age) or micafungin (loading dose 15 mg kg^-1 day^-1 ; maintenance dose 10 mg kg^-1 day^-1 ). PK samples were taken on treatment days 1 and 5. Population parameters were determined using NONMEM and Monte Carlo simulations performed to reach predefined targets. Clinical and laboratory data, and adverse events were collected up to 36 weeks' corrected gestational age or hospital discharge.

RESULTS

Thirty-six neonates were enrolled. The median (range) gestational age was 28.2 (24.1-40.1) and 26.8 (23.5-40.0) weeks for fluconazole and micafungin, respectively. Based on 163 PK samples, the median population clearance (l h^-1 kg^-1 ) and volume of distribution (l kg^-1 ) for fluconazole were: 0.015 [95% confidence interval (CI) 0.008, 0.039] and 0.913, and for micafungin were: 0.020 (95% CI 0.010, 0.023) and 0.354 (95% CI 0.225, 0.482), respectively. The loading dose was well tolerated. No adverse events associated with micafungin or fluconazole were reported.

CONCLUSION

Based on Monte Carlo simulations, a loading dose for fluconazole and dosing higher than recommended for both drugs are required to increase the area under the plasma drug concentration-time curve target attainment rate in neonates.

Pharmacodynamics of vancomycin for CoNS infection: experimental basis for optimal use of vancomycin in neonates

OBJECTIVES

CoNS are the most common cause of neonatal late-onset sepsis. Information on the vancomycin pharmacokinetics/pharmacodynamics against CoNS is limited. The aim of this study was to characterize vancomycin pharmacokinetic/pharmacodynamic relationships for CoNS and investigate neonatal optimal dosage regimens.

METHODS

A hollow fibre and a novel rabbit model of neonatal central line-associated bloodstream CoNS infections were developed. The results were then bridged to neonates by use of population pharmacokinetic techniques and Monte Carlo simulations.

RESULTS

There was a dose-dependent reduction in the total bacterial population and C-reactive protein levels. The AUC/MIC and Cmax/MIC ratios were strongly linked with total and mutant resistant cell kill. Maximal amplification of resistance was observed in vitro at an fAUC/MIC of 200 mg · h/L. Simulations predicted that neonates <29 weeks post-menstrual age are underdosed with standard regimens with respect to older age groups.

CONCLUSIONS

The AUC/MIC and Cmax/MIC ratios are the pharmacodynamic indices that best explain total and resistant cell kill in CoNS infection. This suggests that less-fractionated regimens are appropriate for clinical use and continuous infusions may be associated with increased risk of emergence of antimicrobial resistance. This study has provided the pharmacodynamic evidence to inform an optimized neonatal dosage regimen to take into a randomized controlled trial.

[Legal aspects of consent in children (Part 1)]

In pediatric research, the patient is legally a minor and therefore protected by law. Research can only be conducted after parental consent and patient assent have been obtained. In this context, this review discusses the historical events and documents related to all ethical precautions and obligations. It also underlines that physicians shall respect all legal measures, but that individual involvement must comply with ethical standards while taking into account issues particular to pediatric research related to parental consent and child assent to clinical trials.

[Consent in children: Practical situations (part 2)]

Ethical and regulatory documents frame informed consent in pediatric research; their application is obligatory but may be complex. In this specific context, pediatric investigators have a central ethical role to play to ensure the strict respect of regulatory and ethical requirements adapted to the French legal, social, and cultural context as well as good clinical practices. This article attempts to shed light on the considerations that can allow researchers to come to terms with industrial and institutional demands while responding to the needs of patients, particularly in the domain of pediatric research.

Fluconazole use and safety in the nursery

Fluconazole is a triazole antifungal agent that is widely used in the nursery. It is available in both intravenous and oral formulation, and is active against most of the fungal pathogens that require treatment when retrieved from culture samples in neonatal intensive care units. Although clinical use has been wide for over 15 years, there have been small safety and efficacy studies completed in young infants. Randomised clinical trials assessing effectiveness of this agent in prevention of systemic fungal infections in neonates have been published in the last decade, and one large additional randomised study has been recently completed. Nevertheless, a certain degree of uncertainty still exists regarding the kinetics and appropriate dosing of this agent in premature and term infants, as well as regarding safety. Areas of poignant debate include the feasibility of loading dose strategies, appropriate dosages in the early days of life in the different subgroups of preterm infants, and long-term safety of fluconazole administered in prophylaxis during the first weeks of life in extremely premature infants. This paper reviews the most recent evidence on fluconazole and its role in the NICU settings.

Neonatal cutaneous disseminated aspergillosis in a preterm extremely-low-birth-weight infant with favourable outcome at 3-year follow-up: a case report

Invasive disseminated neonatal aspergillosis is an uncommon disease, with only scattered reports in literature in the last few years. Here we report on a 25-week gestational age, 730 g at birth preterm female infant who developed on day-of-life 10 multiple cutaneous exhulcerative lesions in her right arm, trunk and abdomen. Early recognition and diagnosis of these lesions as a due to cutaneous initial symptom of cutaneous disseminated aspergillosis, as well as prompt treatment with Liposomal amphotericin B + Itraconazole, secured successful recovery from the systemic infection. Skin lesions healed without any surgical treatment. The infant was discharged in good health. Long-term follow-up at three years of age revealed normality of all neurodevelopmental and cognitive parameters. To our knowledge, this is one of the very few cases of survival, free from sequelae, for a preterm infant affected by neonatal cutaneous disseminated aspergillosis.

Correct choices for correct treatments: key issues in the management of Candida infections in preterm neonates

Invasive Candida infections (ICI) have a high burden of morbidity and mortality in the neonatal setting. Although the identification of effective prophylactic strategies has recently led to the prevention of many episodes of systemic fungal disease, the identification of effective treatment strategies is still a priority. The correct choice of the most appropriate antifungal drug for treatment of such infections requires specific expertise, as well as careful consideration of a number of variables related both to the characteristics of the patient and to the peculiarities of these infections in neonates. The ideal antifungal drug for preterm neonates should have a good ability to target fungal biofilms, in order to prevent or improve the course of end-organ localisations. It should also be active against fluconazole-resistant species, as well as safe enough to be used with no or limited interference with other neonatal drugs. In this view, the echinocandin class of antifungal agents has recently proven to be a suitable option for treatment. However, further studies are warranted to better establish kinetics and appropriate dosing of these agents in premature and term infants, as well as their ability to improve late outcomes of ICI.

Clinical characteristics and response to prophylactic fluconazole of preterm VLBW neonates with baseline and acquired fungal colonisation in NICU: data from a multicentre RCT

BACKGROUND

Fungal colonisation by Candida spp. affects a high proportion of VLBW neonates in NICU. However, few data are available on the clinical characteristics of colonisation in preterm infants who are colonised at baseline via vertical transmission, compared to preterms who become colonised during their stay in NICU via horizontal transmission.

MATERIAL AND METHODS

We reviewed the database of a multicentre, randomised trial of prophylactic fluconazole in VLBW neonates conducted in 8 Italian NICUs in the years 2004 and 2005 (Manzoni et al., NEJM 2007;356(24):2483-95). Per the protocol, all enrolled infants underwent weekly surveillance cultures from birth till discharge. We investigated the frequency of the two different modalities of Candida colonisation in this population, as well as the clinical and outcome characteristics possibly related to them.

RESULTS

Overall, Candida colonisation affected 54 of 336 infants (16.1%). Baseline (i.e., detected <3(rd) day of life) colonisation affected 16 (4.7%), and acquired 38 (11.4%), of the 54 colonised preterms. Infants with baseline colonisation had significantly higher birth weight (1229 ± 28 g vs. 1047 g ± 29, p = 0.01) and gestational age (30.2 wks ± 2.7 vs. 28.5 wks ± 2.6, p = 0.01), and were significantly more likely to limit progression from colonisation to invasive Candida infection when fluconazole prophylaxis was instituted (21.6% vs. 42.7%, p = 0.009). Isolation of C. parapsilosis was significantly more frequent in infants with acquired colonisation.

CONCLUSIONS

Infants with baseline and acquired colonisation differ for demographics characteristics and for their response to fluconazole prophylaxis. This information may be useful for targeting more accurate management strategies for these two different groups of colonised preterms in NICU.

Early and late onset sepsis in very-low-birth-weight infants from a large group of neonatal intensive care units

BACKGROUND

Very-low-birth-weight (VLBW, <1500 g birth weight) infants are at high risk for both early- and late-onset sepsis. Prior studies have observed a predominance of Gram-negative organisms as a cause of early-onset sepsis and Gram-positive organisms as a cause of late-onset sepsis. These reports are limited to large, academic neonatal intensive care units (NICUs) and may not reflect findings in other units. The purpose of this study was to determine the risk factors for sepsis, the causative organisms, and mortality following infection in a large and diverse sample of NICUs.

METHODS

We analysed the results of all cultures obtained from VLBW infants admitted to 313 NICUs from 1997 to 2010.

RESULTS

Over 108,000 VLBW infants were admitted during the study period. Early-onset sepsis occurred in 1032 infants, and late-onset sepsis occurred in 12,204 infants. Gram-negative organisms were the most commonly isolated pathogens in early-onset sepsis, and Gram-positive organisms were most commonly isolated in late-onset sepsis. Early- and late-onset sepsis were associated with increased risk of death controlling for other confounders (odds ratio 1.45 [95% confidence interval [CI] 1.21,1.73], and OR 1.30 [95%CI 1.21, 1.40], respectively).

CONCLUSIONS

This is the largest report of sepsis in VLBW infants to date. Incidence for early-onset sepsis and late-onset sepsis has changed little over this 14-year period, and overall mortality in VLBW infants with early- and late-onset sepsis is higher than in infants with negative cultures.

Renal transplantation in children: critical analysis of age related surgical complications

To determine age-related risk factors of urological and vascular complications. We performed a retrospective analysis of the data of 202 renal transplantations in 193 children between 1989 and 2007 at a single institution. Out of 193 grafts (combined renal and liver grafts were excluded), we observed urological complications in 42 cases (21.7%) leading to graft loss in one case and vascular complications in 27 cases (13.9%) leading to graft loss in seven. The urological complications were VUR (n=25, 12.4%), ureteral stricture (n=10, 5%), anastomotic leak (n=4, 2%), ureteral necrosis (n=2, 1%), and incrustative pyelitis (n=1, 0.5%). Vascular complications were arterial stricture (n=14, 7.2%), arterial thrombosis (n=4, 2%), venous thrombosis (n=2, 1%), and others (n=7). Donors aged less than six yr were a risk factor of vascular complications leading to graft loss (p=0.0001), whereas patients with PUV had more urological complications (p=0.001). Overall patient and graft survival is 93.1% and 84% at five yr, respectively. Surgical complications remain a major cause of graft loss (12%) and morbidity in children's kidney transplantation (38.9%). Young age of donors is the major risk factor of early graft loss as a result of vascular complication. However, donor selection based on age is limited by the shortage of organs.

The impact of high-dose methotrexate on intracellular 6-mercaptopurine disposition during interval therapy of childhood acute lymphoblastic leukemia

PURPOSE

Low-dose methotrexate (MTX) therapy is the cornerstone treatment of acute lymphoblastic leukemia (ALL) and may enhance the activation of 6-mercaptopurine (6-MP) to 6-thioguanine nucleotides (6-TGN). Yet, data have established that high-dose MTX (HDMTX) hampers the accumulation of 6-TGN in red blood cells (RBC) and lymphoblasts.

METHODS

To clarify the pharmacokinetic interactions between these two antimetabolites, we serially measured RBC 6-TGN and MTX polyglutamates (MTXPG) levels following repeated courses of HDMTX (5 g/m(2) over 24 h) with daily oral 6-MP (25 mg/m(2)) during interval therapy in 20 children with ALL.

RESULTS

HDMTX produced a rapid reduction in RBC 6-TGN 24 h after the start of MTX, and this effect was sustained at least by the third day (median decrease -21%; P < 0.001). However, a return to pre-infusion of 6-TGN levels was observed by the time of the following HDMTX course 14 days later (P < 0.001). RBC MTX polyglutamates accumulation followed Michaelis-Menten kinetics but was not associated with the change in pre-infusion 6-TGN levels which remained stable during the interval period.

CONCLUSION

HDMTX does not appear to enhance 6-MP activation to 6-TGN. Moreover, given that the deleterious effect of HDMTX on intracellular 6-MP disposition has been shown to be several folds greater in lymphoblasts than in RBC. Our data warrant additional studies elucidating the optimal MTX dose synergizing with 6-MP.

The use of fluconazole in neonatal intensive care units

Preterm neonates in neonatal intensive care units (NICU) are at high risk of invasive fungal infection (IFI), mostly by Candida spp. IFI in such patients is increasingly leading to high morbidity and mortality and frequent neurodevelopmental disabilities in the survivors. Most conditions and risk factors associated with neonatal IFI are unavoidable, being intrinsic to prematurity or related to the aggressive nature of the care these patients require. Neonatal IFI is difficult to diagnose, as candidaemia may be transient and difficult to eradicate due to the high rates of end-organ dissemination. The best option to decrease the burden of disease is thus to prevent it. Fluconazole administration is a suitable strategy and proved effective in many retrospective, single-centre studies and in four randomised, prospective clinical trials. Nevertheless, the use of this azole in high-risk preterm neonates in NICU is not yet a standard of care. This article summarises current evidence on the use of fluconazole in preterm neonates and discusses the concerns surrounding its use in nurseries.