Phenobarbital, Midazolam Pharmacokinetics, Effectiveness, and Drug-Drug Interaction in Asphyxiated Neonates Undergoing Therapeutic Hypothermia

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Evaluation of a system-specific function to describe the pharmacokinetics of benzylpenicillin in term neonates undergoing moderate hypothermia

The pharmacokinetic (PK) properties of intravenous (i.v.) benzylpenicillin in term neonates undergoing moderate hypothermia after perinatal asphyxia were evaluated, as they have been unknown until now. A system-specific modeling approach was applied, in which our recently developed covariate model describing developmental and temperature-induced changes in amoxicillin clearance (CL) in the same patient study population was incorporated into a population PK model of benzylpenicillin with a priori birthweight (BW)-based allometric scaling. Pediatric population covariate models describing the developmental changes in drug elimination may constitute system-specific information and may therefore be incorporated into PK models of drugs cleared through the same pathway. The performance of this system-specific model was compared to that of a reference model. Furthermore, Monte-Carlo simulations were performed to evaluate the optimal dose. The systemspecific model performed as well as the reference model. Significant correlations were found between CL and postnatal age (PNA), gestational age (GA), body temperature (TEMP), urine output (UO; system-specific model), and multiorgan failure (reference model). For a typical patient with a GA of 40 weeks, BW of 3, 000 g, PNA of 2 days (TEMP, 33.5°C), and normal UO (2 ml/kg/h), benzylpenicillin CL was 0.48 liter/h (interindividual variability [IIV] of 49%) and the volume of distribution of the central compartment was 0.62 liter/kg (IIV of 53%) in the system-specific model. Based on simulations, we advise a benzylpenicillin i.v. dose regimen of 75, 000 IU/kg/day every 8 h (q8h), 150, 000 IU/kg/day q8h, and 200, 000 IU/kg/day q6h for patients with GAs of 36 to 37 weeks, 38 to 41 weeks, and ≥42 weeks, respectively. Thesystem-specific model may be used for other drugs cleared through the same pathway accelerating model development

Pharmacokinetics of morphine in encephalopathic neonates treated with therapeutic hypothermia

Contains fulltext : 202110.pdf (publisher's version ) (Open Access

Lymphopenia in atopic dermatitis patients treated with oral immunosuppressive drugs

Introduction: Oral immunosuppressive drugs are commonly used in the treatment of atopic dermatitis (AD). In patients with autoimmune- and rheumatic diseases, these drugs have been associated with lymphopenia. Lymphopenia is related to an increased risk of opportunistic infections. The incidence of lymphopenia in patients with AD treated with oral immunosuppressive drugs is yet unknown. Objective: To evaluate the occurrence of recurrent lymphopenia in patients with AD treated with oral immunosuppressive drugs and to make recommendations for screening in daily practice. Methods: Patients with recurrent lymphopenia (i.e. >5 times lymphocyte counts below 0.8 × 109/L) during treatment with oral immunosuppressive drugs were included from our immunosuppressive drugs database and further analyzed. Results: A total of 360 AD patients, treated with oral immunosuppressive drugs, were screened. A recurrent lymphopenia during treatment was found in 11 patients. In 8/11 patients, recurrent lymphopenia was observed during concomitant treatment with prednisone. No serious infections were observed. Conclusion: Lymphopenia is occasionally seen in AD patients treat with oral immunosuppressive drugs. Concomitant treatment with prednisone seems to be a risk factor. We suggest to include monitoring of lymphocyte counts in the standard follow-up for all AD patients treated with oral immunosuppressive drugs

Phenobarbital, Midazolam Pharmacokinetics, Effectiveness, and Drug-Drug Interaction in Asphyxiated Neonates Undergoing Therapeutic Hypothermia

Background: Phenobarbital and midazolam are commonly used drugs in (near-)term neonates treated with therapeutic hypothermia for hypoxic-ischaemic encephalopathy, for sedation, and/or as anti-epileptic drug. Phenobarbital is an inducer of cytochrome P450 (CYP) 3A, while midazolam is a CYP3A substrate. Therefore, co-treatment with phenobarbital might impact midazolam clearance. Objectives: To assess pharmacokinetics and clinical anti-epileptic effectiveness of phenobarbital and midazolam in asphyxiated neonates and to develop dosing guidelines. Methods: Data were collected in the prospective multicentre PharmaCool study. In the present study, neonates treated with therapeutic hypothermia and receiving midazolam and/or phenobarbital were included. Plasma concentrations of phenobarbital and midazolam including its metabolites were determined in blood samples drawn on days 2-5 after birth. Pharmacokinetic analyses were performed using non-linear mixed effects modelling; clinical effectiveness was defined as no use of additional anti-epileptic drugs. Results: Data were available from 113 (phenobarbital) and 118 (midazolam) neonates; 68 were treated with both medications. Only clearance of 1-hydroxy midazolam was influenced by hypothermia. Phenobarbital co-administration increased midazolam clearance by a factor 2.3 (95% CI 1.9-2.9, p < 0.05). Anticonvulsant effectiveness was 65.5% for phenobarbital and 37.1% for add-on midazolam. Conclusions: Therapeutic hypothermia does not influence clearance of phenobarbital or midazolam in (near-)term neonates with hypoxic-ischaemic encephalopathy. A phenobarbital dose of 30 mg/kg is advised to reach therapeutic concentrations. Phenobarbital co-administration significantly increased midazolam clearance. Should phenobarbital be substituted by non-CYP3A inducers as first-line anticonvulsant, a 50% lower midazolam maintenance dose might be appropriate to avoid excessive exposure during the first days after birth