Pharmacokinetics of Clindamycin in Obese and Nonobese Children.

Although obesity is prevalent among children in the United States, pharmacokinetic (PK) data for obese children are limited. Clindamycin is a commonly used antibiotic that may require dose adjustment in obese children due to its lipophilic properties. We performed a clindamycin population PK analysis using data from three separate trials. A total of 420 samples from 220 children, 76 of whom had a body mass index greater than or equal to the 95th percentile for age, were included in the analysis. Compared to other metrics, total body weight (TBW) was the most robust measure of body size. The final model included TBW and a sigmoidal maturation relationship between postmenstrual age (PMA) and clearance (CL): CL (liters/hour) = 13.8 × (TBW/70)0.75 × [PMA2.83/(39.52.83+PMA2.83)]; volume of distribution (V) was associated with TBW, albumin (ALB), and alpha-1 acid glycoprotein (AAG): V (liters) = 63.6 × (TBW/70) × (ALB/3.3)-0.83 × (AAG/2.4)-0.25 After accounting for differences in TBW, obesity status did not explain additional interindividual variability in model parameters. Our findings support TBW-based dosing for obese and nonobese children.

Population Pharmacokinetic Assessment and Pharmacodynamic Implications of Pediatric Cefepime Dosing for Susceptible-Dose-Dependent Organisms.

The Clinical and Laboratory Standards Institute (CLSI) revised cefepime (CFP) breakpoints forEnterobacteriaceaein 2014, and MICs of 4 and 8 µg/ml were reclassified as susceptible-dose dependent (SDD). Pediatric dosing to provide therapeutic concentrations against SDD organisms has not been defined. CFP pharmacokinetics (PK) data from published pediatric studies were analyzed. Population PK parameters were determined using NONMEM, and Monte Carlo simulation was performed to determine an appropriate CFP dosage regimen for SDD organisms in children. A total of 664 CFP plasma concentrations from 91 neonates, infants, and children were included in this analysis. The median patient age was 1.0 month (interquartile range [IQR], 0.2 to 11.2 months). Serum creatinine (SCR) and postmenstrual age (PMA) were covariates in the final PK model. Simulations indicated that CFP dosing at 50 mg/kg every 8 h (q8h) (as 0.5-h intravenous [i.v.] infusions) will maintain free-CFP concentrations in serum of >4 and 8 µg/ml for >60% of the dose interval in 87.1% and 68.6% of pediatric patients (age, ≥30 days), respectively, and extending the i.v. infusion duration to 3 h results in 92.3% of patients with free-CFP levels above 8 µg/ml for >60% of the dose interval. CFP clearance (CL) is significantly correlated with PMA and SCR. A dose of 50 mg/kg of CFP every 8 to 12 h does not achieve adequate serum exposure for older children with serious infections caused by Gram-negative bacilli with a MIC of 8 µg/ml. Prolonged i.v. infusions may be useful for this population.

Longitudinal assessment of bone growth and development in a facility-based population of young adults with cerebral palsy.

AIM: Osteoporosis is a significant clinical problem in persons with moderate to severe cerebral palsy (CP), causing fractures with minimal trauma. Over the past decade, most studies examining osteoporosis and CP have been cross-sectional in nature, focused exclusively on children and adolescents and only involving one evaluation of bone mineral density (BMD). The purpose of this study was to assess BMD in a group including adults with CP, and changes in each individual's BMD over a 5- to 6-year period. METHOD: The study group included 40 residents of a long-term care facility aged 6 to 26 years at the time of their initial evaluation. Twenty-one patients (52.5%) were male, 35 (88%) were white, and 38 (95%) were in Gross Motor Function Classification System level V. BMD was assessed by dual-energy X-ray absorptiometry on the right and left distal femurs for three distinct regions of interest. RESULTS: Five residents had a fracture that occurred during the study period; this represented a fracture rate of 2.1% per year in the study group. Longitudinally, annualized change in the median BMD was 0.7% to 1.0% per year in the different regions of the distal femur, but ranged widely among the study group, with both increases and decreases in BMD. Increase in BMD over time was negatively correlated with age and positively correlated with change in weight. INTERPRETATION: Changes in BMD over time in profoundly involved persons with CP can range widely, which is important to recognize when evaluating potential interventions to improve BMD. Age and changes in body weight appear the most relevant factors.

Efficacy of intravenous lidocaine to reduce pain and distress associated with propofol infusion in pediatric patients during procedural sedation.

BACKGROUND: Research suggests that young children experience an increased incidence and severity of discomfort during propofol infusion. Evaluations of varied interventions to reduce or eliminate this discomfort with adult subjects suggest that premedication with intravenously administered lidocaine (0.5 mg/kg) offers the best overall effectiveness. OBJECTIVE: Because this regimen's efficacy in a pediatric population is undocumented, we conducted a randomized, double-blind, placebo-controlled study to determine the effectiveness of intravenous lidocaine pretreatment to alleviate pain in pediatric subjects before propofol infusion. METHODS: Subjects (aged 2-7 years) scheduled for painless diagnostic procedures received either a saline placebo or 1 of 2 lidocaine doses before administering propofol. To capture the patient's baseline behavioral state, a trained observer administered the validated face, legs, activity, cry, consolability pain assessment scale before propofol infusion. During deep sedation induction, the sedating physician, a trained research assistant, and the patient's parent documented maximum distress using a 100-mm visual analog scale (VAS). RESULTS: Ninety-one subjects participated. We found no difference in VAS pain scores between groups pretreated with lidocaine 0.25 mg/kg, lidocaine 0.5 mg/kg, and placebo. Statistical analysis also found no interrater differences between parents, physician, or observer VAS scores. CONCLUSIONS: Our data do not support using lidocaine pretreatment to alleviate pain/discomfort in pediatric patients during propofol infusion.

Direct care staff and parents'/legal guardians' perspectives on end-of-life care in a long-term care facility for medically fragile and intellectually disabled pediatric and young adult residents.

OBJECTIVE: Children and young adults with severe disabilities and their families are faced with enormous challenges throughout the lifespan, including admitting the child to a long-term care facility (LTCF) and making end-of-life (EOL) care decisions. While children are residents of these specialized LTCF, the majority of their daily care, even up until death, is provided by nursing aides or habilitation aides (HAs) with limited training and educational backgrounds compared with other licensed healthcare providers. The purpose of this study was to determine the impact of a resident's EOL experience on the primary HAs and parents/guardians. METHOD: Thirty-five resident deaths occurred at Hattie Larlham Center for Children with Disabilities (HLCCD) between January 1, 2006 and February 28, 2009. The HAs and parents/legal guardians were identified for each death and invited to complete three surveys per resident (FAMCARE, Impact of Events Scale (IES)-revised, and Perspective on End-of-Life Care) to assess their experience. There were 112 surveys mailed to 62 HAs and 47 surveys mailed to 47 parents. RESULTS: Forty-two surveys were returned from 18/62 HAs (response rate 29%) and 11/47 parents/legal guardians completed the surveys (response rate 23%). The FAMCARE survey found that parents were more satisfied with the EOL care than were the HAs. The IES-revised found no difference in traumatic responses from either group. Comments from the Perspective on End-of-Life Care survey were analyzed qualitatively for common themes including pain control, respect, decision making, environmental needs, resources, and support. SIGNIFICANCE OF RESULTS: Because of a low response rate, it was difficult to draw significant conclusions; however, several interesting trends were noted regarding the number of deaths HAs experienced, satisfaction with care, and distress. The special needs of this population and their caregivers can provide crucial insights into interventions (e.g. chaplaincy support, debriefings, anticipatory counseling, environmental changes) that might be of benefit for any caregiver or parent of a child with a long-term, chronic condition, particularly involving developmental disability.

Model-Informed Precision Dosing Guidance of Ethosuximide Developed from a Randomized Controlled Clinical Trial of Childhood Absence Epilepsy.

Ethosuximide was identified as the optimal option for new-onset childhood absence epilepsy (CAE) in a randomized, two-phase dose escalation comparative effectiveness trial of ethosuximide, lamotrigine, and valproic acid. However, 47% of ethosuximide initial monotherapy participants experienced short-term treatment failure. This study aimed to characterize the initial monotherapy ethosuximide exposure-response relationship and to propose model-informed precision dosing guidance. Dose titration occurred over a 16-20-week period until patients experienced seizure freedom or intolerable side effects. Subjects with initial monotherapy failure were randomized to one of the other two medications and dose escalation was repeated. A population pharmacokinetic model was created using plasma concentration data (n = 1,320), collected at 4-week intervals from 211 unique participants during both the initial and second monotherapy phases. A logistic regression analysis was performed on the initial monotherapy cohort (n = 103) with complete exposure-response data. Eighty-four participants achieved seizure freedom with a wide range of ethosuximide area under the curves (AUC) ranging from 420 to 2,420 µg·h/mL. AUC exposure estimates for achieving a 50% and 75% probability of seizure freedom were 1,027 and 1,489 µg·h/mL, respectively, whereas the corresponding cumulative frequency of intolerable adverse events was 11% and 16%. Monte Carlo Simulation indicated a daily dose of 40 and 55 mg/kg to achieve 50% and 75% probability of seizure freedom in the overall population, respectively. We identified the need for adjusted mg/kg dosing in different body weight cohorts. This ethosuximide proposed model-informed precision dosing guidance to achieve seizure freedom carries promise to optimize initial monotherapy success for patients with CAE.

Emergence of linezolid-resistant Staphylococcus aureus after prolonged treatment of cystic fibrosis patients in Cleveland, Ohio.

Linezolid (LZD)-resistant Staphylococcus aureus (LRSA) isolates were monitored from 2000 to 2009 in Cleveland, OH. LRSA first emerged in 2004 only in cystic fibrosis (CF) patients, with 11 LRSA-infected CF patients being identified by 2009. LRSA was isolated from 8 of 77 CF patients with S. aureus respiratory tract infection treated with LZD from 2000 to 2006. Analysis of clinical data showed that the 8 CF patients with LRSA received more LZD courses (18.8 versus 5.9; P = 0.001) for a longer duration (546.5 versus 211.9 days; P < 0.001) and had extended periods of exposure to LZD (83.1 versus 30.1 days/year; P < 0.001) than the 69 with LZD-susceptible isolates. Five LRSA isolates included in the clinical analysis (2000 to 2006) and three collected in 2009 were available for molecular studies. Genotyping by repetitive extrapalindromic PCR and pulsed-field gel electrophoresis revealed that seven of these eight LRSA strains from unique patients were genetically similar. By multilocus sequence typing, all LRSA isolates were included in clonal complex 5 (seven of sequence type 5 [ST5] and one of ST1788, a new single-locus variant of ST5). However, seven different variants were identified by spa typing. According to the Escherichia coli numbering system, seven LRSA isolates contained a G2576T mutation (G2603T, S. aureus numbering) in one to four of the five copies of domain V of the 23S rRNA genes. One strain also contained a mutation (C2461T, E. coli numbering) not previously reported. Two strains, including one without domain V mutations, possessed single amino acid substitutions (Gly152Asp or Gly139Arg) in the ribosomal protein L3 of the peptidyltransferase center, substitutions not previously reported in clinical isolates. Emergence of LRSA is a serious concern for CF patients who undergo prolonged courses of LZD therapy.

Concomitant Ceftriaxone and Intravenous Calcium Therapy in Infants.

OBJECTIVE: To determine if increased mortality could be detected with the administration of ceftriaxone and IV calcium in infants through an analysis of a large repository of electronic health records. METHODS: Patients were split into 3 groups: 1) neonates, 2) infants, and 3) infants <1 year whose age was not specified. Deaths were classified into mutually exclusive categories based on the administration and timing of ceftriaxone and IV calcium. Crude death rates were calculated, and logistic regression modeling was used to calculate adjusted relative odds of death with associated covariates. RESULTS: A total of 259,149 infants were identified. Of 79,038 neonates, the proportion of patients that received ceftriaxone and IV calcium within 48 hours who died was 3.8%, compared with 1.95% (IV calcium), 0.3% (ceftriaxone), 1.54% (IV fluids), and 2.03% (parenteral nutrition). For 102,456 infants, the proportions of deaths were 5.47% (ceftriaxone and IV calcium within 48 hours), 0.45% (IV calcium), 0.15% (ceftriaxone), 0.39% (IV fluids), and 5.5% (parenteral nutrition). Multivariate analysis showed increased odds of death in infants who received ceftriaxone and IV calcium within 48 hours, regardless of age, and propensity score-matched analysis showed a more than 2-fold increased risk for death. CONCLUSIONS: The increased risk for death following ceftriaxone and IV calcium administration was noted not only in neonates, but among older infants as well.

Tolerability of Aerosolized Versus Intravenous Pentamidine for Pneumocystis jirovecii Pneumonia Prophylaxis in Immunosuppressed Pediatric, Adolescent, and Young Adult Patients.

OBJECTIVES: Pentamidine is an antifungal that is used alternatively to sulfamethoxazole-trimethoprim for the prophylaxis and treatment of Pneumocystis jirovecii pneumonia (PJP). The primary objective of this study was to assess the tolerability of aerosolized versus intravenous pentamidine for PJP prophylaxis in pediatric, adolescent, and young adult immunosuppressed patients. Secondary objectives included comparing pentamidine formulation reaction to dosing frequency and diagnosis. METHODS: This retrospective chart review used electronic medical record (EMR) data from patients at a tertiary care pediatric teaching institution from January 1, 2014, to January 1, 2017. Information used from the EMR included pentamidine dosing, ordering, and laboratory values. Inclusion criteria consisted of patients with a cancer diagnosis, hematopoietic stem cell transplant (HSCT) recipients, and renal transplant recipients who received pentamidine for PJP prophylaxis. RESULTS: Ninety-six patients met inclusion criteria, of which 31 received aerosolized pentamidine. Ten of the 96 patients experienced a drug-related reaction to either aerosolized or intravenous pentamidine (p = 0.134). Nine of 10 patients who experienced a reaction received intravenous pentamidine versus 1 patient who received aerosolized pentamidine (p = 0.132). In those patients who reacted to pentamidine there was a higher incidence of reactions after subsequent administration (p = 0.039) and in patients with a blood cancer diagnosis (p = 0.042). CONCLUSIONS: Data suggest that patients who receive aerosolized pentamidine may tolerate therapy better compared to intravenous administration. Additional studies involving larger numbers of pediatric, adolescent, and young adult patients are needed for stronger statistically significant clinical differences in tolerability of aerosolized versus intravenous pentamidine.

How can we improve the safe use of herbal medicine and other natural products? A clinical pharmacologist mission.

INTRODUCTION: Three major classes of natural products (NPs) for medicinal purposes or improving wellbeing are generally available in the US: conventional drugs of herbal origin, botanical drugs, and dietary supplements (DSs). Consumer consumption of DSs is growing annually. The U.S. FDA regulates conventional and botanical drugs for safety and efficacy; however, DSs are minimally regulated. AREAS COVERED: This article will: i) highlight the importance of NP as a significant source of prescription drugs; ii) discuss differences in the regulation of conventional drugs of NP product, botanical drugs, and DSs; iii) discuss the safety and efficacy of DSs and iv) make recommendations for improvement of safety for minimally regulated NPs. EXPERT OPINION: Toxicities associated with the use of NPs, including vitamins and DSs, are mainly due to excessive use and interactions with conventional drug(s) and may represent challenges for clinicians. Conventional and botanical-based prescription drugs are rarely associated with unknown toxicities. However, DSs are minimally regulated and can produce severe adverse effects. We believe that clinical pharmacologists can have a role in developing criteria for DS safety analysis. There is also the potential for a standardized NP stewardship program(s) and the development of NP policies and practices nationally and globally.

Variations in amoxicillin pharmacokinetic/pharmacodynamic parameters may explain treatment failures in acute otitis media.

Pharmacokinetic/pharmacodynamic (PK/PD) modeling and Monte Carlo simulations suggest that amoxicillin should rarely fail as therapy for Streptococcus pneumoniae and Haemophilus influenzae acute otitis media (AOM) infections except when the S. pneumoniae are highly penicillin resistant or the H. influenzae are beta-lactamase producing. However, important and not infrequent exceptions to this expectation have been described. The objective of this review was to define the biologic variations in amoxicillin PK/PD parameters for the treatment of AOM in children and assess whether these variations could explain why the commonly employed amoxicillin PK/PD model is imperfect in predicting outcome for every patient in this clinical setting. To this end, a literature search of MEDLINE (1966-2006) and EMBASE (1974-2006) was conducted to identify studies that evaluated ampicillin or amoxicillin intestinal absorption, serum concentrations, and/or middle ear fluid (MEF) concentrations. Analysis of studies identified for review showed that the intestinal bioavailability of amoxicillin depends on passive diffusion and a saturable 'pump' mechanism that produces variable serum concentrations of the antibacterial agent. Indeed, substantial differences from patient to patient in serum (5- to 30-fold) and MEF (up to 20-fold) concentrations of amoxicillin occur following oral administration, and 15-35% of children have no detectable amoxicillin in MEF. These findings suggest that variability in PK/PD parameters may impact amoxicillin concentrations in serum and MEF, possibly explaining some AOM treatment failures.

Single-dose pharmacokinetics of oral and intravenous pantoprazole in children and adolescents.

The primary objective was to determine the pharmacokinetics of single oral and intravenous doses of pantoprazole in children 2 to 16 years of age. The secondary objective was to assess the safety and tolerability of these doses. Male and female hospitalized and nonhospitalized patients from ages 5 to 16 years received single oral doses (20 mg or 40 mg), and those from ages 2 to 16 years received single intravenous doses (0.8 mg/kg or 1.6 mg/kg) of pantoprazole. The plasma concentration-time data for each patient were analyzed using noncompartmental methods. Routine safety and tolerability assessments were also obtained. The mean values for peak plasma concentration and total area under the plasma concentration-time curve increased with increasing dose. Pharmacokinetic values were similar in patients from ages 2 to 16 years and to those previously obtained in adults. Statistically significant differences were observed for dose-normalized pantoprazole area under the plasma concentration-time curve when compared between CYP2C19 extensive metabolizers with 1 versus 2 functional alleles. All adverse events were mild in severity and considered to be unrelated to study drug. The pharmacokinetic profile of oral and intravenous pantoprazole was similar in children ages 2 to 16 years. The doses used here were safe and well tolerated in this population.

Developmental Changes in Pharmacokinetics and Pharmacodynamics.

Effective drug therapy to optimally influence disease requires an understanding of a drug's pharmacokinetic, pharmacodynamic, and pharmacogenomic interrelationships. In pediatrics, age is a continuum that can and does add variability in drug disposition and effect. This article addresses the many important factors that influence drug disposition and effect relative to age. What is known about the influence of maturation on the processes of drug absorption, distribution, metabolism, excretion, and drug receptor dynamics are outlined. Our state of understanding of many of these factors remains in flux, however, and only with additional study will we be able to better anticipate and model drug-response relationships across the age continuum. Being able to continuously improve our care of the ill pediatric patient while simultaneously being able to accurately determine the utility of new drugs and chemical entities in this population requires our enhanced understanding of these disposition characteristics.

A 26-week open-label study of quetiapine in children with conduct disorder.

OBJECTIVE: The aim of this study was to describe the long-term safety and effectiveness of quetiapine in conduct disorder (CD). METHODS: This was an 18-week outpatient follow-up study of an acute trial that enrolled aggressive children ages 6-12 years with a primary diagnosis of CD. To be enrolled into this study, subjects had to have successfully completed participation in the initial 8-week, open-label, outpatient quetiapine trial. Psychometric measures included the Rating of Aggression Against People and/or Property Scale (RAAPP), the Nisonger Child Behavior Rating Form (NCBRF), the Conners' Parent Rating Scale (CPRS-48), the Clinical Global Impressions Scale of Severity (CGI-S), and the Children's Global Assessment Scale. RESULTS: Nine males with a mean age of 8.9 (SD = 1.2) years were treated. The median quetiapine dose at end of study was 150 mg/day (range 75-350). Mean psychometric scores did not change substantively from baseline. No patients experienced extrapyramidal side effects. Three subjects discontinued due to study nonadherence. No patients discontinued treatment due to an adverse event. CONCLUSIONS: These preliminary data suggest that quetiapine might be a generally safe and effective maintenance treatment for aggressive children with CD who initially respond to an acute therapeutic trial of quetiapine. More research is needed to confirm or refute these initial findings.

Venlafaxine in the treatment of children and adolescents with attention-deficit/hyperactivity disorder.

OBJECTIVE: The objectives of this pilot study were to explore the changes in symptom severity, tolerability, and the pharmacodynamics of venlafaxine treatment in youths with attention-deficit/hyperactivity disorder (ADHD). METHODS: This was a 2-week, open-label, outpatient trial of venlafaxine in children and adolescents, ages 5-17 years, with ADHD. Three dosing strata, 0.5, 1.0, and 2.0 mg/kg per day, were examined. ADHD symptom severity and improvement assessments included the ADHD Rating Scale (ARS-IV) and the Clinical Global Impressions Scale (CGI). During this study, venlafaxine, O-desmethylvenlafaxine (ODV), norepinephrine, and serotonin concentrations were obtained. RESULTS: Thirty-eight participants (33 males) were treated in this trial. Overall, parent-completed and teacher-completed ARS-IV total scores showed a statistically significant positive change at the end of the study when compared to baseline (p < 0.05). Significant increases in plasma venlafaxine concentrations were observed at day 15 when compared to day 8 (p = 0.04). In addition, plasma norepinephrine and serotonin concentrations were found to be significantly decreased from baseline at end of study (p < 0.05). Four patients ended participation in the study prematurely: lost to follow up (n = 2), withdrawal of consent (n = 1), and worsening of ADHD symptoms after 8 days of treatment (n = 1). There were no discontinuations due to other adverse events. CONCLUSIONS: Venlafaxine appeared to offer some benefit and appears to be relatively safe for the short-term treatment of ADHD in this open-label trial. The pharmacodynamics of venlafaxine in youths are consistent with serotonergic and neuradrenergic modulation.

The pharmacokinetics and safety of micafungin, a novel echinocandin, in premature infants.

BACKGROUND: : Candidal fungal infection rates in neonates are increasing and are a significant cause of mortality, especially in low birth weight infants. Micafungin is an echinocandin that works by inhibiting 1,3-beta-D-glucan synthase, an enzyme responsible for fungal cell wall synthesis. The objective of this study was to determine the safety and pharmacokinetics of micafungin in premature infants. METHODS: : This was a phase I, single-dose, multicenter, open-label, sequential-dose trial of intravenous micafungin investigating 3 doses (0.75 mg/kg, 1.5 mg/kg and 3.0 mg/kg) in 18 premature infants weighing >1000 g (n = 6 in each dosage group). A further 5 infants (500-1000 g) were enrolled in the 0.75 mg/kg dosage group only. RESULTS: : The mean +/- standard deviation gestational age in the >1000 g dosage group was 26.4 +/- 2.4 weeks and, on entry, patients had one or more of a variety of underlying conditions, including sepsis, pneumonia and other infections caused by Candida or other species. Micafungin pharmacokinetics in preterm infants appears linear. However, premature infants >1000 g on average displayed a shorter half-life (8 hours) and a more rapid rate of clearance (approximately 39 mL/h per kg) compared with published data in older children and adults. All doses of micafungin were well tolerated and no serious drug-related adverse events were observed. CONCLUSIONS: : Single doses of micafungin, ranging up to 3.0 mg/kg, appear well tolerated in premature infants weighing >1000 g. The drug's elimination half-life and total plasma clearance in preterm infants appear dissimilar to published values for these parameters in older children and adults. The reason(s) for this apparent difference remain to be investigated.

Combination lithium and divalproex sodium in pediatric bipolar symptom re-stabilization.

OBJECTIVE: It has been reported that bipolar disorder may become less responsive to previously effective treatment with each symptomatic relapse. The primary goal of this study was to assess the rate of re-stabilization after the resumption of lithium (Li) plus divalproex (DVPX) following relapse on either agent as monotherapy. METHOD: This is a prospective, 8-week, open-label outpatient Li/DVPX combination therapy trial. Patients ages 5 to 17 years with bipolar disorder type I or II, who had achieved symptom remission with Li/DVPX combination therapy and subsequently relapsed during treatment with Li or DVPX monotherapy were enrolled between January 1999 and January 2003. RESULTS: Thirty-eight patients with a mean age of 10.5 years entered the study. Thirty-four (89.5%) patients responded to treatment with Li/DVPX mood stabilizer therapy alone, but four patients required adjunctive antipsychotic treatment to address residual symptomatology. Overall, reinitiation of Li/DVPX combination therapy was well tolerated with no subjects discontinuing because of a medication-related adverse event. CONCLUSIONS: It appears that most youths with bipolar disorder who stabilize on combination Li/DVPX therapy and subsequently relapse during monotherapy can safely and effectively be re-stabilized with the reinitiation of Li/DVPX combination treatment.