Pharmacokinetics of ticarcillin-clavulanate in premature infants.

Ticarcillin-clavulanate covers a broad spectrum of pathogens that are common in premature infants. In infants <30 weeks gestational age, pharmacokinetic data to guide ticarcillin-clavulanate dosing are lacking. We enrolled 15 premature infants <30 weeks gestational age, determined pharmacokinetic parameters, and performed dosing simulations to determine optimal dosing for ticarcillin-clavulanate. The infants had a median (range) postnatal age (PNA) of 18 days (6-44 days) and gestational age of 25 weeks (23-28 weeks). Clearance was lower in infants with a PNA <14 days (0.050 L/kg/h [range 0.043-0.075]) compared with a PNA ≥14-45 days (0.078 L/kg/h [0.047-0.100]), consistent with maturation of renal function. Dosing simulations determined that ticarcillin 75 mg/kg q12h (PNA <14 days) or q8h (PNA ≥ 14-45 days) achieved the target exposure for organisms with a minimum inhibitory concentration ≤16 µ/mL in >90% of simulated infants. For highly resistant organisms (minimum inhibitory concentration 32 µg/mL), increased dosing frequency or extended infusion are necessary.

Population pharmacokinetics of sildenafil in extremely premature infants.

AIMS: To characterize the population pharmacokinetics (PK) of sildenafil and its active metabolite, N-desmethyl sildenafil (DMS), in premature infants. METHODS: We performed a multicentre, open-label trial to characterize the PK of sildenafil in infants ≤28 weeks gestation and < 365 postnatal days (cohort 1) or < 32 weeks gestation and 3-42 postnatal days (cohort 2). In cohort 1, we obtained PK samples from infants receiving sildenafil as ordered per the local standard of care (intravenous [IV] or enteral). In cohort 2, we administered a single IV dose of sildenafil and performed PK sampling. We performed a population PK analysis and dose-exposure simulations using the software NONMEM®. RESULTS: We enrolled 34 infants (cohort 1 n = 25; cohort 2 n = 9) and collected 109 plasma PK samples. Sildenafil was given enterally (0.42-2.09 mg/kg) in 24 infants in cohort 1 and via IV (0.125 or 0.25 mg/kg) in all infants in cohort 2. A 2-compartment PK model for sildenafil and 1-compartment model for DMS, with presystemic conversion of sildenafil to DMS, characterized the data well. Coadministration of fluconazole (n = 4), a CYP3A inhibitor, resulted in an estimated 59% decrease in sildenafil clearance. IV doses of 0.125, 0.5 and 1 mg/kg every 8 hours (in the absence of fluconazole) resulted in steady-state maximum sildenafil concentrations that were generally within the range of those reported to inhibit phosphodiesterase type 5 activity in vitro. CONCLUSIONS: We successfully characterized the PK of sildenafil and DMS in premature infants and applied the model to inform dosing for a follow-up, phase II study.

Population Pharmacokinetics of Fluconazole in Premature Infants with Birth Weights Less than 750 Grams.

Fluconazole is an effective agent for prophylaxis of invasive candidiasis in premature infants. The objective of this study was to characterize the population pharmacokinetics (PK) and dosing requirements of fluconazole in infants with birth weights of <750 g. As part of a randomized clinical trial, infants born at <750 g birth weight received intravenous (i.v.) or oral fluconazole at 6 mg/kg of body weight twice weekly. Fluconazole plasma concentrations from samples obtained by either scheduled or scavenged sampling were measured using a liquid chromatography-tandem mass spectrometry assay. Population PK analysis was conducted using NONMEM 7.2. Population PK parameters were allometrically scaled by body weight. Covariates were evaluated by univariable screening followed by multivariable assessment. Fluconazole exposures were simulated in premature infants using the final PK model. A population PK model was developed from 141 infants using 604 plasma samples. Plasma fluconazole PK were best described by a one-compartment model with first-order elimination. Only serum creatinine was an independent predictor for clearance in the final model. The typical population parameter estimate for oral bioavailability in the final model was 99.5%. Scavenged samples did not bias the parameter estimates and were as informative as scheduled samples. Simulations indicated that the study dose maintained fluconazole troughs of >2,000 ng/ml in 80% of simulated infants at week 1 and 59% at week 4 of treatment. Developmental changes in fluconazole clearance are best predicted by serum creatinine in this population. A twice-weekly dose of 6 mg/kg achieves appropriate levels for prevention of invasive candidiasis in extremely premature infants.

Effect of fluconazole prophylaxis on candidiasis and mortality in premature infants: a randomized clinical trial.

IMPORTANCE: Invasive candidiasis in premature infants causes death and neurodevelopmental impairment. Fluconazole prophylaxis reduces candidiasis, but its effect on mortality and the safety of fluconazole are unknown. OBJECTIVE: To evaluate the efficacy and safety of fluconazole in preventing death or invasive candidiasis in extremely low-birth-weight infants. DESIGN, SETTING, AND PATIENTS: This study was a randomized, blinded, placebo-controlled trial of fluconazole in premature infants. Infants weighing less than 750 g at birth (N = 361) from 32 neonatal intensive care units (NICUs) in the United States were randomly assigned to receive either fluconazole or placebo twice weekly for 42 days. Surviving infants were evaluated at 18 to 22 months corrected age for neurodevelopmental outcomes. The study was conducted between November 2008 and February 2013. INTERVENTIONS: Fluconazole (6 mg/kg of body weight) or placebo. MAIN OUTCOMES AND MEASURES: The primary end point was a composite of death or definite or probable invasive candidiasis prior to study day 49 (1 week after completion of study drug). Secondary and safety outcomes included invasive candidiasis, liver function, bacterial infection, length of stay, intracranial hemorrhage, periventricular leukomalacia, chronic lung disease, patent ductus arteriosus requiring surgery, retinopathy of prematurity requiring surgery, necrotizing enterocolitis, spontaneous intestinal perforation, and neurodevelopmental outcomes-defined as a Bayley-III cognition composite score of less than 70, blindness, deafness, or cerebral palsy at 18 to 22 months corrected age. RESULTS: Among infants receiving fluconazole, the composite primary end point of death or invasive candidiasis was 16% (95% CI, 11%-22%) vs 21% in the placebo group (95% CI, 15%-28%; odds ratio, 0.73 [95% CI, 0.43-1.23]; P = .24; treatment difference, -5% [95% CI, -13% to 3%]). Invasive candidiasis occurred less frequently in the fluconazole group (3% [95% CI, 1%-6%]) vs the placebo group (9% [95% CI, 5%-14%]; P = .02; treatment difference, -6% [95% CI, -11% to -1%]). The cumulative incidences of other secondary outcomes were not statistically different between groups. Neurodevelopmental impairment did not differ between the groups (fluconazole, 31% [95% CI, 21%-41%] vs placebo, 27% [95% CI, 18%-37%]; P = .60; treatment difference, 4% [95% CI, -10% to 17%]). CONCLUSIONS AND RELEVANCE: Among infants with a birth weight of less than 750 g, 42 days of fluconazole prophylaxis compared with placebo did not result in a lower incidence of the composite of death or invasive candidiasis. These findings do not support the universal use of prophylactic fluconazole in extremely low-birth-weight infants. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00734539.

Safety of sildenafil in extremely premature infants: a phase I trial.

OBJECTIVE: To characterize the safety of sildenafil in premature infants. STUDY DESIGN: A phase I, open-label trial of sildenafil in premature infants receiving sildenafil per usual clinical care (cohort 1) or receiving a single IV dose of sildenafil (cohort 2). Safety was evaluated based on adverse events (AEs), transaminase levels, and mean arterial pressure monitoring. RESULTS: Twenty-four infants in cohort 1 (n = 25) received enteral sildenafil. In cohort 2, infants received a single IV sildenafil dose of 0.25 mg/kg (n = 7) or 0.125 mg/kg (n = 2). In cohort 2, there was one serious AE related to study drug involving hypotension associated with a faster infusion rate than specified by the protocol. There were no AEs related to elevated transaminases. CONCLUSION: Sildenafil was well tolerated by the study population. Drug administration times and flush rates require careful attention to prevent infusion-related hypotension associated with faster infusions of IV sildenafil in premature infants. CLINICAL TRIAL: ClinicalTrials.gov Identifier: NCT01670136.

Antibiotic Safety and Effectiveness in Premature Infants With Complicated Intraabdominal Infections.

BACKGROUND: In premature infants, complicated intraabdominal infections (cIAIs) are a leading cause of morbidity and mortality. Although universally prescribed, the safety and effectiveness of commonly used antibiotic regimens have not been established in this population. METHODS: Infants ≤33 weeks gestational age and <121 days postnatal age with cIAI were randomized to ≤10 days of ampicillin, gentamicin, and metronidazole (group 1); ampicillin, gentamicin, and clindamycin (group 2); or piperacillin-tazobactam and gentamicin (group 3) at doses stratified by postmenstrual age. Due to slow enrollment, a protocol amendment allowed eligible infants already receiving study regimens to enroll without randomization. The primary outcome was mortality within 30 days of study drug completion. Secondary outcomes included adverse events, outcomes of special interest, and therapeutic success (absence of death, negative cultures, and clinical cure score >4) 30 days after study drug completion. RESULTS: One hundred eighty infants [128 randomized (R), 52 nonrandomized (NR)] were enrolled: 63 in group 1 (45 R, 18 NR), 47 in group 2 (41 R, 6 NR), and 70 in group 3 (42 R, 28 NR). Thirty-day mortality was 8%, 7%, and 9% in groups 1, 2, and 3, respectively. There were no differences in safety outcomes between antibiotic regimens. After adjusting for treatment group and gestational age, mortality rates through end of follow-up were 4.22 [95% confidence interval (CI): 1.39-12.13], 4.53 (95% CI: 1.21-15.50), and 4.07 (95% CI: 1.22-12.70) for groups 1, 2, and 3, respectively. CONCLUSIONS: Each of the antibiotic regimens are safe in premature infants with cIAI. CLINICAL TRIAL REGISTRATION: NCT0199499.

Pneumoperitoneum without Intestinal Perforation in a Neonate: Case Report and Literature Review.

Pneumoperitoneum in a preterm neonate usually indicates perforation of the intestine and is considered a surgical emergency. However, there are cases of pneumoperitoneum with no evidence of rupture of the intestine reported in the literature. We report a case of pneumoperitoneum with no intestinal perforation in a preterm neonate with respiratory distress syndrome who was on high frequency oscillatory ventilation (HFOV). He developed bilateral pulmonary interstitial emphysema with localized cystic lesion, likely localized pulmonary interstitial emphysema, and recurrent pneumothoraces. He was treated with dexamethasone to wean from the ventilator. Pneumoperitoneum developed in association with left sided pneumothorax following mechanical ventilation and cardiopulmonary resuscitation. Pneumoperitoneum resolved after the pneumothorax was resolved with chest tube drainage. He died from acute cardiorespiratory failure. At autopsy, there was no evidence of intestinal perforation. This case highlights the fact that pneumoperitoneum can develop secondary to pneumothorax and does not always indicate intestinal perforation or require exploratory laparotomy.