Pragmatic physiologically-based pharmacokinetic modeling to support clinical implementation of optimized gentamicin dosing in term neonates and infants: proof-of-concept

IntroductionModeling and simulation can support dosing recommendations for clinical practice, but a simple framework is missing. In this proof-of-concept study, we aimed to develop neonatal and infant gentamicin dosing guidelines, supported by a pragmatic physiologically-based pharmacokinetic (PBPK) modeling approach and a decision framework for implementation.MethodsAn already existing PBPK model was verified with data of 87 adults, 485 children and 912 neonates, based on visual predictive checks and predicted-to-observed pharmacokinetic (PK) parameter ratios. After acceptance of the model, dosages now recommended by the Dutch Pediatric Formulary (DPF) were simulated, along with several alternative dosing scenarios, aiming for recommended peak (i.e., 8–12 mg/L for neonates and 15–20 mg/L for infants) and trough (i.e., <1 mg/L) levels. We then used a decision framework to weigh benefits and risks for implementation.ResultsThe PBPK model adequately described gentamicin PK. Simulations of current DPF dosages showed that the dosing interval for term neonates up to 6 weeks of age should be extended to 36–48 h to reach trough levels <1 mg/L. For infants, a 7.5 mg/kg/24 h dose will reach adequate peak levels. The benefits of these dose adaptations outweigh remaining uncertainties which can be minimized by routine drug monitoring.ConclusionWe used a PBPK model to show that current DPF dosages for gentamicin in term neonates and infants needed to be optimized. In the context of potential uncertainties, the risk-benefit analysis proved positive; the model-informed dose is ready for clinical implementation

Pharmacological and Parenteral Nutrition-Based Interventions in Microvillus Inclusion Disease

Microvillus inclusion disease (MVID) is a rare inherited and invariably fatal enteropathy, characterized by severe intractable secretory diarrhea and nutrient malabsorption. No cure exists, and patients typically die during infancy because of treatment-related complications. The need for alternative treatment strategies is evident. Several pharmacological interventions with variable successes have been tried and reported for individual patients as part of their clinical care. Unfortunately, these interventions and their outcomes have remained hidden in case reports and have not been reviewed. Further, recent advances regarding MVID pathogenesis have shed new light on the outcomes of these pharmacological interventions and offer suggestions for future clinical research and trials. Hence, an inventory of reported pharmacological interventions in MVID, their rationales and outcomes, and a discussion of these in the light of current knowledge is opportune. Together with a discussion on MVID-specific pharmacokinetic, -dynamic, and -genetic concerns that pose unique challenges regarding pharmacological strategies, we envision that this paper will aid researchers and clinicians in their efforts to develop pharmacological interventions to combat this devastating disease

Tacrolimus-induced nephrotoxicity and genetic variability:A review

Background: Calcineurin inhibition (CNI) is the mainstay of immunosuppressant therapy for most solid organ transplant patients. High tacrolimus levels are related with acute nephrotoxicity, but the relationship with chronic toxicity is less clear. Variation in disposition of tacrolimus is associated with genetic variation in CYP3A5. Hence, could genetic variation in CYP3A5 or other genes involved in tacrolimus disposition and effect be associated with a risk for tacrolimus-induced nephrotoxicity? To perform a review of the literature and to identify if genetic variation in CYP3A5 or other genes involved in tacrolimus disposition or effect may be associated with tacrolimus-induced nephrotoxicity and/or renal dysfunction in solid organ transplant recipients. Material/Methods: Pubmed/Medline, Embase and Google were searched from their inception till November 8th 2010 with the search terms 'tacrolimus', 'genetics', and 'nephrotoxicity' or 'renal dysfunction'. References of relevant articles were screened as well. Results: We identified 13 relevant papers. In kidney recipients, associations between donor ABCB1, recipient CCR5 genotype and tacrolimus-induced nephrotoxicity were found. CYP3A5 genotype studies in kidney recipients yielded contradictory results. In liver recipients, a possible association between recipient ACE, CYP3A5, ABCB1 and CYP2C8 genetic polymorphisms and tacrolimus-induced nephrotoxicity was suggested. In heart recipients, TGF-β genetic polymorphisms were associated with tacrolimus-induced nephrotoxicity. The quality of the studies varied considerably. Conclusions: Limited evidence suggests that variation in genes involved in pharmacokinetics (ABCB1 and CYP3A5) and pharmacodynamics (TGF-β, CYP2C8, ACE, CCR5) of tacrolimus may impact a transplant recipients' risk to develop tacrolimus-induced nephrotoxicity across different transplant organ groups.</p

The effect of distant reiki on pain in women after elective Caesarean section: a double-blinded randomised controlled trial

Introduction: Approximately 25% of all babies in North America are delivered via Caesarean section (C-section). Though a common surgical procedure, C-section recovery can be painful. Opioids, specifically codeine, are commonly used to ease pain; however, its active metabolite, morphine, passes into breast milk, and may produce unwanted side effects in neonates; therefore, alternatives to opioids are being sought. Reiki is an ancient Japanese form of healing where practitioners transfer healing energy through light touch and positive healing intention. Although 1.2 million Americans use reiki to reduce pain or depression, there is a lack of strong evidence supporting its effectiveness. A recent systematic review showed existing studies to be of poor methodological quality, with the common limitation of lack of blinding. To overcome this issue, the authors used distant reiki to assess its effectiveness in reducing pain following an elective C-section. Methods: In this randomised, double-blinded study, women who underwent an elective C-section were allocated to either usual care (control, n=40) or three distant reiki sessions in addition to usual care (n=40). Pain was assessed using a visual analogue scale (VAS). The primary endpoint was the Area Under the VAS-Time Curve (AUC) for days 1-3. Secondary measures included: The proportion of women who required opioid medications and dose consumed, rate of healing and vital signs. Results: AUC for pain was not significantly different in the distant reiki and control groups (mean±SD; 212.16104.7 vs 223.16117.8; p=0.96). There were no significant differences in opioid consumption or rate of healing; however, the distant reiki group had a significantly lower heart rate (74.368.1 bpm vs 79.867.9 bpm, p=0.003) an

Quantifying the Pharmacodynamics of Morphine in the Treatment of Postoperative Pain in Preverbal Children

While the pharmacokinetics of morphine in children have been studied extensively, little is known about the pharmacodynamics of morphine in this population. Here, we quantified the concentration‐effect relationship of morphine for postoperative pain in preverbal children between 0 and 3 years of age. For this, we applied item response theory modeling in the pharmacokinetic/pharmacodynamic analysis of COMFORT‐Behavior (COMFORT‐B) scale data from 2 previous clinical studies. In the model, we identified a sigmoid maximal efficacy model for the effect of morphine and found that in 26% of children, increasing morphine concentrations were not associated with lower pain scores (nonresponders to morphine up‐titration). In responders to morphine up‐titration, the COMFORT‐B score slowly decreases with increasing morphine concentrations at morphine concentrations >20 ng/mL. In nonresponding children, no decrease in COMFORT‐B score is expected. In general, lower baseline COMFORT‐B scores (2.1 points on average) in younger children (postnatal age 10 days. These findings support a dosing regimen previously suggested by Krekels et al, which would put >95% of patients within this morphine target concentration range at steady state. Our modeling approach provides a promising platform for pharmacodynamic research of analgesics and sedatives in children