Effect of age and birth weight on indomethacin pharmacodynamics in neonates treated for patent ductus arteriosus

Neonatal acute kidney injury during indomethacin therapy: does it predict ductal closure?

BACKGROUND

Preterm newborns are at risk for patent ductus arteriosus, and non-steroidal anti-inflammatory drugs are often used to facilitate patent ductus arteriosus closure. Acute kidney injury is common in critically ill neonates and may be caused by non-steroidal anti-inflammatory drugs. We sought to describe the incidence of acute kidney injury among preterm infants receiving indomethacin and determine whether acute kidney injury during indomethacin therapy is associated with subsequent patent ductus arteriosus closure.

METHODS

Retrospective cohort including neonates < 33 weeks gestational age, admitted to two level IIIb neonatal intensive care units between November 2016 and November 2019, who received indomethacin in the first 2 weeks of life. Acute kidney injury in the 7-day period after treatment was defined by neonatal modified Kidney Disease Improving Global Outcomes (KDIGO) criteria. Patent ductus arteriosus closure was defined clinically and/or via echocardiogram. Clinical characteristics were extracted from medical records. Association between acute kidney injury during treatment and successful closure of patent ductus arteriosus was evaluated using chi-square tests and logistic regression.

RESULTS

One hundred fifty preterm infants were included; acute kidney injury occurred in 8% (all KDIGO Stage 1). Patent ductus arteriosus closed in 52.9% of the non-acute kidney injury group and 66.7% of the acute kidney injury group (p = 0.55). Serum creatinine was checked a mean of 3.1 times in the acute kidney injury group and 2.2 times in the non-acute kidney injury group. There was no difference in survival.

CONCLUSION

We found no association between acute kidney injury during indomethacin therapy and patent ductus arteriosus closure. Paucity of serum creatinine values likely underdiagnosed acute kidney injury. Surveillance of kidney function during indomethacin therapy using more sensitive renal biomarkers may better identify infants who develop acute kidney injury in the context of non-steroidal anti-inflammatory drug use.

Effects of prophylactic indomethacin on intraventricular hemorrhage and adverse outcomes in neonatal intensive care unit

OBJECTIVE

To identify the relationship between prophylactic indomethacin (PI) administration and incidence of intraventricular hemorrhage.

STUDY DESIGN

A retrospective analysis of extremely premature infants <27 weeks gestational age born between January 2014 and September 2020.

RESULTS

A total of 421 infants were included from three of Nationwide Children's Hospital delivery centers. Of those 255 (61%) received PI. After adjustment by inverse proportionality treatment weighting (IPTW), no differences were found in incidence of intraventricular hemorrhage (IVH) at the time of the first ultrasound, 31% vs. 33% in PI and control groups respectively (p = 0.68). The rate of rise of serum creatinine from baseline to day of life four was significantly higher in the PI group (0.14 mg/dl PI and 0.03 mg/dl control, p < 0.001).

CONCLUSION

PI was not associated with any benefit in prevention of IVH, but is associated with adverse effects including acute rise in creatinine.

Prophylactic Indomethacin in extremely preterm infants: association with death or BPD and observed early serum creatinine levels

OBJECTIVES

To identify the relationship between prophylactic indomethacin (PI) administration and (1) mortality and bronchopulmonary dysplasia (BPD) at 36-week postmenstrual age (PMA) (primary outcome), and (2) to evaluate for PI-associated acute kidney injury.

STUDY DESIGN

Retrospective cohort investigation of 22-28 weeks gestation infants (N = 1167) who were admitted to Nationwide Children's Hospital on postnatal days 0-1 between May 2009 and September 2017 and survived ≥24-h postnatal. The associations of PI treatment with mortality or BPD, and other secondary outcomes, were evaluated via multivariable robust-error-variance Poisson regression.

RESULTS

The adjusted risks of death or BPD (1.02, 95% CI: 0.83, 1.25), BPD (0.97, 95% CI: 0.77, 1.21), and death 1.33 (95% CI: 0.84, 2.10) by 36-week PMA were unchanged following PI treatment after multivariable adjustment. No changes in mean creatinine levels were detected in exposed versus unexposed infants to suggest PI-induced AKI.

CONCLUSION

Prophylactic indomethacin treatment was unrelated to mortality or BPD outcomes.

Association between changes in urine output and successful indomethacin treatment for patent ductus arteriosus in preterm neonates

AIM

To investigate the relationship between changes in urine output during indomethacin treatment and ductal closure in preterm neonates.

METHODS

It is a retrospective study in neonates ≤32 weeks who had received two courses of indomethacin for PDA treatment over a 5-year period. Indomethacin courses with pre- and post-echocardiography confirmation of PDA status were included. Various urine output indices were collected and compared between successful versus unsuccessful indomethacin courses. Indomethacin treatment success was defined as: (i) where PDA closed or became haemodynamically insignificant (hisPDA) after treatment and (ii) only including neonates where PDA had complete closure after treatment. ROC analysis was performed to examine predictive ability of urine output during indomethacin for treatment success.

RESULTS

One hundred and eight indomethacin courses (first course: 52, second course: 56) in 80 neonates were included. The mean gestational age and birthweight were 25.4 ± 1.3 weeks and 762 ± 165 g, respectively. Irrespective of the definition used, there was no significant differences seen in any of urine output parameters between groups, except for a higher urine output during indomethacin associated with complete PDA closure (3.6 ± 1.3 vs. 3.0 ± 1.0 mL/kg/h, P = 0.02). The incidence of significant oliguria, hyponatraemia and need to withhold/delay indomethacin doses were also similar across groups.

CONCLUSION

Urine output was not a useful predictor of ductal response to indomethacin treatment in preterm neonates.

Role of dopamine and selective dopamine receptor agonists on mouse ductus arteriosus tone and responsiveness

BACKGROUND

Indomethacin treatment for patent ductus arteriosus (PDA) is associated with acute kidney injury (AKI). Fenoldopam, a dopamine (DA) DA₁-like receptor agonist dilates the renal vasculature and may preserve renal function during indomethacin treatment. However, limited information exists on DA receptor-mediated signaling in the ductus and fenoldopam may prevent ductus closure given its vasodilatory nature.

METHODS

DA receptor expression in CD-1 mouse vessels was analyzed by qPCR and immunohistochemistry. Concentration-response curves were established using pressure myography. Pretreatment with SCH23390 (DA₁-like receptor antagonist), phentolamine (α -adrenergic receptor antagonist) or indomethacin addressed mechanisms for DA-induced changes. Fenoldopam's effects on postnatal ductus closure were evaluated in vivo.

RESULTS

DA₁ receptors were expressed equally in ductus and aorta. High-dose DA induced modest vasoconstriction under newborn O₂ conditions. Phentolamine inhibited DA-induced constriction, while SCH23390 augmented constriction, consistent with a vasodilatory role for DA₁ receptors. Despite this, fenoldopam had little effect on ductus tone nor indomethacin- or O₂-induced constriction and did not impair postnatal closure in vivo.

CONCLUSION(S)

DA receptors are present in the ductus but have limited physiologic effects. DA-induced ductus vasoconstriction is mediated via α-adrenergic pathways. The absence of DA₁-mediated impairment of ductus closure supports the study of potential role for fenoldopam during PDA treatment.

Molecular docking and pharmacokinetic evaluation of natural compounds as targeted inhibitors against Crz1 protein in Rhizoctonia solani

Crz1p regulates Calcineurin, a serine-threonine-specific protein phosphatase, in Rhizoctonia solani. It has attracted consideration as a novel target of antifungal therapy based on studies in numerous pathogenic fungi, including, Cryptococcus neoformans, Candida albicans and Aspergillus fumigatus. To investigate whether Calcineurin can be a useful target for the treatment of Crz1 protein in R. solani causing wet root rot in Chickpea. The work presented here reports the in-silico studies of Crz1 protein against natural compounds. This study Comprises of quantitative structure-toxicity relationship (QSTR) and quantitative structure-activity relationship (QSAR). All compounds showed high binding energy for Crz1 protein through molecular docking. Further, a pharmacokinetic study revealed that these compounds had minimal side effects. Biological activity spectrum prediction of these compounds showed potential antifungal properties by showing significant interaction with Crz1. Hence, these compounds can be used for the prevention and treatment of wet root rot in Chickpea.

Acetaminophen for Patent Ductus Arteriosus in Extremely Low-Birth-Weight Neonates

OBJECTIVE

Although non-steroidal anti-inflammatory drugs (NSAIDs) are the current standard therapy for the treatment of patent ductus arteriosus (PDA), many neonates have contraindications to receiving or may fail NSAID therapy. To avoid surgical ligation, these patients may benefit from an alternative therapy. The objective of this research is to report the efficacy and safety of acetaminophen for the treatment of PDA in a cohort of premature neonates.

METHODS

Demographics and clinical course were retrospectively evaluated for all neonates admitted during the study period who received acetaminophen for the treatment of PDA. Initial acetaminophen dosing was 15 mg/kg every 6 hours (88% intravenous). Efficacy was analyzed from ductal constriction on echocardiogram as well as need for further PDA treatment. Markers of hepatic and renal function as well as respiratory support and neonatal morbidities were evaluated to describe the safety of acetaminophen.

RESULTS

Forty-one neonates were identified with a median birth weight of 760 g (IQR 614-948 g) and median gestational age of 25 weeks (IQR 24-27 weeks). Treatment was initiated at a median postnatal age of 15 days (IQR 8-19 days) for a median duration of 7 days (IQR 6-10 days). Twenty-seven neonates (66%) required no further PDA treatment, with echocardiographic PDA closure documented in 10 neonates (24%) and reduced ductal size in 15 neonates (37%). No clinically significant adverse effects attributable to acetaminophen therapy were detected.

CONCLUSIONS

Most patients in this study responded to acetaminophen treatment for PDA, indicating that this therapy may be an option for extremely low-birth-weight neonates in order to avoid surgical ligation.

Polymorphisms in CYP2C9 are associated with response to indomethacin among neonates with patent ductus arteriosus

BackgroundPatent ductus arteriosus (PDA) is a common complication seen in preterm infants. Indomethacin is routinely used to treat PDA. Evidence suggests that the response of indomethacin is highly heritable. This study investigated the association between single-nucleotide polymorphisms (SNPs) in CYP2C9 and the closure of PDA in response to indomethacin.MethodsSix SNPs in CYP2C9 were analyzed for association with indomethacin response. A case-control analysis was performed among neonates who responded to indomethacin (responders) and among those who required surgical ligation (non-responders). Independent transmission disequilibrium tests were performed among parent-child trios of responders and non-responders.ResultsThe G allele of rs2153628 was associated with increased odds of response to indomethacin in the case-control analysis (odds ratios (OR): 1.918, 95% confidence interval (CI): 1.056, 3.483). Among indomethacin responders, the G allele of rs2153628 and the T allele of rs1799853 were overtransmitted from the parents to their child (OR: 2.667, 95% CI: 1.374, 5.177 and OR: 2.375, 95% CI: 1.040, 5.425, respectively), consistent with the case-control analysis.ConclusionWe identified an association between two SNPs in CYP2C9, rs2153628 and rs1799853, and indomethacin response for the treatment of PDA. These findings suggest that response to indomethacin in the closure of PDA may be influenced by polymorphisms associated with altered indomethacin metabolism.

Risk of nonsteroidal anti-inflammatory drug-associated renal dysfunction among neonates diagnosed with patent ductus arteriosus and treated with gentamicin

OBJECTIVE

To evaluate the risk of nonsteroidal anti-inflammatory drug (NSAID) therapy-associated acute kidney injury (AKI) among neonates diagnosed with patent ductus arteriosus (PDA) who are treated with gentamicin.

STUDY DESIGN

Multicenter retrospective observational study of patients ⩽44 postmenstrual weeks of age diagnosed with PDA who received gentamicin during hospitalization between January 2006 and December 2014. Patients with and without NSAID exposure were matched on covariates associated with AKI and NSAID therapy. The primary end point, AKI, was defined according to Kidney Disease Improving Global Outcomes neonatal criteria.

RESULTS

The rate of AKI for the entire cohort (n=594) was 12% (n=71). Among neonates receiving NSAIDS, 14.8% (n=44) experienced an AKI as compared to 9.1% (n=27) for those who were not exposed (relative risk, 1.6; 95% confidence interval, 1.0 to 2.6). Therefore, the attributable risk of NSAID use was 5.7% (95% confidence interval, 0.5 to 11.0).

CONCLUSION

Among neonates with PDA and receiving gentamicin, NSAID therapy increases the risk of AKI by about 6%.

Factors associated with non-response to second course indomethacin for PDA treatment in preterm neonates

BACKGROUND

Failure of first course of indomethacin (FCI) for patent ductus arteriosus (PDA) treatment in preterm neonates often prompts clinicians to consider a second course (SCI).

OBJECTIVE

To identify factors including baseline characteristics and response to FCI that are associated with non-response to SCI for PDA treatment in preterm neonates.

METHODS

In this retrospective observational study, neonates ≤32 weeks admitted to a tertiary NICU over 5 years who received two indomethacin courses for PDA treatment were reviewed. Only neonates with echocardiograms (ECHO) immediately before and after receipt of each indomethacin course were included. Primary outcome was non-response to SCI. Baseline characteristics and response to FCI were compared between responders and non-responders of SCI.

RESULTS

Of the 98 neonates enrolled, 47 (48%) had non-response to SCI. Of them, 27 patients (57%) had prior non-response to FCI, while of the 51 neonates who responded to SCI, 24 neonates (47%) had prior non-response to FCI. The adjusted risk of non-response to SCI in patients who had non-response to FCI was 37% higher (relative risk = 1.37, 95%CI: 0.87-1.80; p = .07) compared to those who had response to FCI. Multivariable analysis showed that increasing gestational age (AOR: 1.6, 95%CI: 1.1-2.3, p = .03) was associated with a higher odds of non-response to SCI while the odds of non-response to SCI increased by 90% in patients with non-response to FCI (AOR: 1.9, 95%CI: 0.8-4.5; p = .15) compared to those with success of FCI, although no statistical significance was observed.

CONCLUSIONS

Advanced gestational age was the predictor of non-response to SCI in preterm neonates.

Effect of NSAIDs and diuretics on nephrogenesis in an ex vivo embryogenic kidney model

The kidney is one of the key organs in clearing foreign compounds. The effects of drugs on the developing kidney are relatively unknown. We studied the direct effect of furosemide, hydrochlorothiazide, ibuprofen, and indomethacin on kidney development in an ex vivo embryonic kidney model. At embryonic day 13, metanephroi were dissected from mice and cultured in control media or media supplemented with various clinically relevant concentrations of drugs. The ureteric tree was visualized by whole-mount staining and branching was evaluated by counting. Additionally, gene expression levels of Wt1, Sox9, Bmp7, Fgf8, and Gdnf were investigated. No distinct differences were noted on either ureteric tip development or gene expression analysis for each drug after 24 hr of exposure. Even though short-term exposure to clinically relevant concentrations seems not to disturb renal development, future research is needed to study prolonged or repeated exposures.

Clinical pharmacology of indomethacin in preterm infants: implications in patent ductus arteriosus closure

Indomethacin is a non-steroidal anti-inflammatory drug that is a potent inhibitor of prostaglandin E(2) synthesis. After birth, the ductus arteriosus closes spontaneously within 2-4 days in term infants. The major factor closing the ductus arteriosus is the tension of oxygen, which increases significantly after birth. Prostaglandin E(2) has the opposite effect to that of oxygen; it relaxes smooth muscle and tends to inhibit the closure of the ductus arteriosus. In preterm infants with respiratory distress syndrome, the ductus arteriosus fails to close (patent ductus arteriosus [PDA]) because the concentration of prostaglandin E2 is relatively high. PDA occurs in more than 70 % of neonates weighing less than 1,500 g at birth. The aim of this article was to review the published data on the clinical pharmacology of indomethacin in preterm infants in order to provide a critical analysis of the literature and a useful tool for physicians. The bibliographic search was performed electronically using the PubMed and EMBASE databases as search engines and February 2012 was the cutoff point. A remarkable interindividual variability was observed for the half-life (t(½)), clearance (CL), and volume of distribution (V(d)) of indomethacin. Prophylactic indomethacin consists of a continuous infusion of low levels of indomethacin and may be useful in preterm infants. Extremely preterm infants are less likely to respond to indomethacin. Infants with a postnatal age of 2 months do not respond to treatment with indomethacin. Indomethacin has several adverse effects, the most common of which is renal failure. An increase in serum creatinine of ≥0.5 % mg/dL after indomethacin was observed in about 10-15 % of the patients and creatinine returns to a normal level about 1 week after cessation of therapy. Indomethacin should be administered intravenously by syringe pump for at least 30 min to minimize adverse effects on cerebral, gastrointestinal, and renal blood flow velocities. A prolonged course of indomethacin appears to reduce the risk of severe intracranial hemorrhage and renal impairment in patients with PDA. In conclusion, indomethacin is a useful drug to treat PDA.

Paracetamol to induce ductus arteriosus closure: is it valid?

There remains a need for alternative medical treatments for patent ductus arteriosus (PDA) closure in extreme preterm neonates because of therapeutic failure and adverse effects associated with non-selective cyclo-oxygenase inhibitors. Reports of an association between paracetamol exposure and PDA closure in a limited number of extreme preterm neonates have been published. However, causality cannot be taken for granted because a link between the current knowledge of the clinical pharmacology of paracetamol and (patho)physiology of ductal closure is not known. In contrast to non-selective cyclo-oxygenase inhibitors, paracetamol has limited effects at peripheral sites, is a poor antithrombotic and anti-inflammatory drug and exerts its effects primarily within the central nervous system. Although paracetamol appears an effective and safe analgesic in term and near term neonates, its effectiveness and safety for PDA closure are uncertain because the drug is administered in high doses and there remain a limited number of observations in this specific subpopulation so far. Prospective comparative trials are reasonable and are urgently needed to establish both the effectiveness and safety data of paracetamol when used for this indication.

Optimum Use of Therapeutic Drug Monitoring and Pharmacokinetics-Pharmacodynamics in the NICU

Therapeutic drug monitoring is increasingly giving way to dosing drugs based on population-based pharmacokinetic parameters, even when pharmacokinetic values vary quite a bit in individual patients. Further, drug concentrations are often considered appropriate if they are within a defined therapeutic range, even if the patient response is suboptimal. This lecture discusses the limitations of therapeutic ranges in neonates, and proposes greater emphasis on pharmacodynamic curves to individualize drug therapy. Examples are provided using methylxanthines, indomethacin, antiepileptic drugs and aminoglycosides. The potential to use pharmacokinetic findings to describe physiologic changes and occasionally assist with diagnosis is also discussed.

Determinants of surgical repair of patent ductus arteriosus in low-birth-weight infants

PURPOSE

To identify risk factors related to the failure of indomethacin therapy and the need for surgical repair in patent ductus arteriosus (PDA) in extremely low-birth-weight (<1000 g) infants (ELBWI).

METHODS

Study subjects were 36 ELBWI with PDA born at a single tertiary perinatal center. They were classified into those who required surgery due to failure of indomethacin treatment (surgical group, n = 21) and those with effective indomethacin treatment (non-surgical group, n = 15). The odds ratios (ORs) and 95% confidence intervals (95% CIs) for the relationship between selected risk factors and surgical treatment of PDA were calculated.

RESULTS

Gestational age of <28 weeks and diameter of PDA of 2 mm or more were independent and significant determinants of the need for surgical repair of PDA (adjusted ORs [95% CIs] = 9.91 [1.16-84.48] and 24.80 [2.72-225.74], respectively). The need for surgical repair of PDA did not correlate with sex, birth weight, 1-min Apgar score, left atrium diameter/aortic diameter (LA/Ao), left ventricular internal dimension at end-diastole, prophylaxes with indomethacin, and total dosage of indomethacin.

CONCLUSIONS

Gestational age at birth of <28 weeks and diameter of PDA of 2 mm or more are determinants of failure of indomethacin treatment for PDA and the need for surgical repair.

Management of patent ductus arteriosus in term or near-term neonates with respiratory distress

BACKGROUND

Respiratory distress and patent ductus arteriosus (PDA) in neonates are mutually perpetuating. Contrary to the situation in premature infants, the recognition, clinical relevance and optimal management of PDA in full-term neonates are unclear. The present study aimed to identify PDA as a possible cause of respiratory distress in term and near-term neonates, and to examine the clinical responsiveness of PDA to different treatment modalities in mature-gestational-age neonates.

METHODS

Patients with gestational ages of over 34 weeks were included in this retrospective chart review; they had PDA as the sole recognizable cause of respiratory distress and were free of all other diseases. Clinical responsiveness to different regimens, including conservative treatment, drug therapy with preload reduction and inotropic agent with or without the addition of indomethacin, and surgical intervention were analyzed.

RESULTS

Forty-four neonates qualified for this study. Six received no treatment and their cardiorespiratory symptoms resolved within 1 week (regimen A). Symptoms in 11 neonates were relieved after use of diuretic and inotropic agents (regimen B). Twelve neonates became asymptomatic without further intervention after indomethacin treatment in addition to preload reduction and inotropes (regimen C). A total of 15 of the 44 infants underwent PDA ligation (regimen D) due to persistent heart failure following regimens B or C, but had speedy resolution of respiratory symptoms following surgery. There were significant differences in birth body weight and hemodynamic variation based on left atrium to aortic root dimensional ratio between the treatment (regimens B, C and D) and non-treatment (regimen A) groups (p < 0.05).

CONCLUSION

PDA plays an important role in prolonging respiratory distress in term or near-term neonates. Although most infants respond to noninvasive medical treatment, surgical ligation during the neonatal period is warranted in certain mature infants. Surgical treatment should be considered in patients with smaller birth body weights and those with increased left atrium to aortic root dimensional ratios.

Indomethacin pharmacodynamics are altered by surfactant: a possible challenge to current indomethacin dosing guidelines created before surfactant availability

The effect of surfactant administration for respiratory distress syndrome (RDS) on indomethacin (INDO) pharmacodynamics and dosing requirements for patent ductus arteriosus (PDA) closure and renal toxicity was evaluated. A 22-year prospective cohort study including 442 INDO-treated patients given 466 INDO treatment courses. The database included demographic information, medical problems, and medications. Neonates with a PDA confirmed by echocardiography were treated with INDO, 0.25-0.3 mg/kg. Subsequent INDO dosing was based on a combined pharmacokinetic/pharmacodynamic (PK/PD) approach. Data were fit to an Emax model and ANOVA was used to compare mean closure levels between groups. PDA closure was successful in 405 of 442 patients (91.6%) and in 434 of 466 treatment courses (93.1%) using an individualized PK/PD dosing approach. Renal toxicity was documented in 56 of 442 patients (12.7%) or 56 of 466 treatment courses (12.0%). Patients not treated with synthetic surfactant trended toward lower mean INDO concentrations at PDA closure compared to patients treated with synthetic surfactant (1.65 vs. 2.01 mg/l; P > 0.05) and significantly lower mean INDO concentrations at PDA closure compared to patients treated with natural surfactant (1.65 vs. 2.15 mg/l; P < 0.002). This requires an increased total dose of ~0.3 mg/kg or an individual dose increase of 0.1 mg/kg. Administration of natural or synthetic surfactant for RDS may increase the INDO concentrations and doses needed for PDA closure in premature infants.

Furosemide in preterm infants treated with indomethacin for patent ductus arteriosus

OBJECTIVE

To evaluate the effect of furosemide on renal function and water balance in preterm infants treated with indomethacin (3 x 0.2 mg/kg at 12-h intervals) for symptomatic patent ductus arteriosus.

PATIENTS AND METHODS

We performed a retrospective multi-centre double cohort study in preterm infants <32 weeks of gestational age. Thirty-two infants treated with furosemide (1 mg/kg i.v.) before each indomethacin dose (furosemide group) were matched with 32 infants with indomethacin treatment alone (control-group). Renal effects (urine output, weight gain, serum creatinine, sodium concentration) were registered.

RESULTS

The study groups were comparable for gestational age, birth weight and day of therapy. Pretreatment differences were observed for urine output, weight and serum sodium. However, no differences were noticed in day-to-day urine output change or weight gain between the groups. A significant increase in serum creatinine concentration (50% vs. control, 18%; p < 0.05) and a concomitant significant decrease in serum sodium (-9 vs. control, -3 mmoL/L; p < 0.05) in the furosemide group was observed 72-96 h after starting therapy.

CONCLUSION

Furosemide before each indomethacin dose resulted in a significant increase in serum creatinine and hyponatremia, without increasing urine output.

Analysis of outcome in 298 extremely low-birth-weight infants with patent ductus arteriosus

PURPOSE

Indomethacin is accepted therapy for patent ductus arteriosus (PDA) in ELBW infants (<1000 g). We hypothesize that surgical ligation may provide comparatively superior outcomes in select ELBW infants.

METHODS

Predischarge outcomes of 298 ELBW infants with echocardiography-proven PDA were retrospectively compared by treatment provided: no treatment (group 1, n = 54), indomethacin (group 2, n = 140), ligation (group 3, n = 46), and ligation after indomethacin failure (group 4, n = 58). chi(2) and Wilcoxon rank sum tests were used to test for significance. Institutional review board approval was obtained (IRB/05-00395).

RESULTS

Group 3 had significantly lower gestational age (P < .001), birth weight (P = .006), and 5-minute Apgar scores (P = .03) compared with group 2. Group 3 and group 1 had a higher rate of pretreatment intraventricular hemorrhage (IVH) compared with group 2 (P < .001). By contrast, posttreatment complications including acute renal failure, necrotizing enterocolitis, thrombocytopenia, and IVH occurred more frequently in groups 2 (P = .004) and 4 (P = .001) compared with group 3. Survival was 57.7% in group 1 compared with groups 2, 3, and 4 (82.4%, 86.0%, and 92.7% respectively; P = .001). Preoperative conditions associated with nonsurvival include gestational age (P = .009), birth weight (P = .002), maternal preeclampsia (P = .015), 5-minute Apgar score (P = .013), and sepsis (P = .018). Posttreatment complications associated with nonsurvival include acute renal failure (P = .002), thrombocytopenia (P = .002), and necrotizing enterocolitis (P = .034). Survival was not influenced by any congenital comorbidity, pre- or posttreatment IVH, diameter of the PDA, or recurrence of the PDA after indomethacin therapy.

CONCLUSIONS

(1) Patent ductus arteriosis requires treatment in ELBW infants to maximize survival. (2) Indomethacin and surgical ligation permit equivalent survival in low-risk ELBW infants, but indomethacin results in a high failure and complication rate requiring operative salvage in a number of patients. (3) Surgical ligation permits survival of high-risk ELBW infants with a low complication rate and is preferable to indomethacin in ELBW infants with the above risk factors.

Increased indomethacin dosing for persistent patent ductus arteriosus in preterm infants: a multicenter, randomized, controlled trial

OBJECTIVE

We conducted a multicenter, randomized, controlled trial to determine whether higher doses of indomethacin would improve the rate of patent ductus arteriosus (PDA) closure.

STUDY DESIGN

Infants (<28 weeks gestation) who received a conventional, prophylactic 3-dose course of indomethacin were eligible if they had continued evidence of persistent ductus patency on an echocardiogram obtained before the third prophylactic indomethacin dose. Infants (n = 105) were randomized to receive an extended 3-day course of either low-dose (0.1 mg/kg/d) or higher-dose (0.2 or 0.5 mg/kg/d) indomethacin. An echocardiogram was obtained 24 hours after the last dose of study drug.

RESULTS

Despite increasing serum indomethacin concentrations by 2.9-fold in the higher-dose group, we failed to detect a significant decrease in the rate of persistent PDA (low = 52%; higher = 45%, P = .50). The higher-dose group had a significantly higher occurrence of serum creatinine >2 mg/100 mL (low = 6%, higher = 19%, P < .05) and moderate/severe retinopathy of prematurity (ROP) (low = 15%, higher = 36%, P < .025). The incidence of moderate/severe ROP was directly related to the poststudy indomethacin concentrations (odds ratio = 1.75, confidence interval: 1.15-2.68, P < .01).

CONCLUSION

Increasing indomethacin concentrations above the levels achieved with a conventional dosing regimen had little effect on the rate of PDA closure but was associated with higher rates of moderate/severe ROP and renal compromise.

The ontogeny of drug metabolism enzymes and implications for adverse drug events

Profound changes in drug metabolizing enzyme (DME) expression occurs during development that impacts the risk of adverse drug events in the fetus and child. A review of our current knowledge suggests individual hepatic DME ontogeny can be categorized into one of three groups. Some enzymes, e.g., CYP3A7, are expressed at their highest level during the first trimester and either remain at high concentrations or decrease during gestation, but are silenced or expressed at low levels within one to two years after birth. SULT1A1 is an example of the second group of DME. These enzymes are expressed at relatively constant levels throughout gestation and minimal changes are observed postnatally. ADH1C is typical of the third DME group that are not expressed or are expressed at low levels in the fetus, usually during the second or third trimester. Substantial increases in enzyme levels are observed within the first one to two years after birth. Combined with our knowledge of other physiological factors during early life stages, knowledge regarding DME ontogeny has permitted the development of robust physiological based pharmacokinetic models and an improved capability to predict drug disposition in pediatric patients. This review will provide an overview of DME developmental expression patterns and discuss some implications of the data with regards to drug therapy. Common themes emerging from our current knowledge also will be discussed. Finally, the review will highlight gaps in knowledge that will be important to advance this field.

Continuous infusion versus intermittent bolus doses of indomethacin for patent ductus arteriosus closure in symptomatic preterm infants

BACKGROUND

Indomethacin is a prostaglandin inhibitor used for the prevention and the treatment of patent ductus arteriosus (PDA). Although a 3-dose schedule has been commonly used, there is no consensus on optimal dosage and duration of indomethacin therapy for PDA closure. There are potential adverse effects of indomethacin use in premature infants such as a reduction in cerebral, mesenteric and renal blood flow and platelet dysfunction. Administering indomethacin continuously over 36-hours has been suggested as a safer and more effective option to prevent such adverse effects.

OBJECTIVES

To compare the efficacy and safety of continuous infusion versus bolus administration of indomethacin in closing a symptomatic PDA in preterm infants.

SEARCH STRATEGY

The standard search strategy of Cochrane Neonatal Review was used: MEDLINE and EMBASE (1966 - March 2007), Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2007), bibliographies of reviews and trials were examined for references to other trials, previous symposia proceedings published in Pediatric Research (Pediatric Academic Societies Annual Meeting Abstract Book, 1972 - 2006). No language restrictions were applied.

SELECTION CRITERIA

Randomized and quasi-randomized controlled trials comparing continuous indomethacin infusion to bolus doses for closure of a symptomatic PDA in preterm infants with a symptomatic PDA diagnosed clinically and/or by echocardiography.

DATA COLLECTION AND ANALYSIS

The methodological quality of each study was assessed. Authors were contacted regarding missing data as well as to inquire about the outcomes that were not reported. Meta-analysis was performed to calculate relative risk (RR), risk difference (RD) and 95% confidence intervals (CI).

MAIN RESULTS

Only two small trials comparing continuous versus bolus indomethacin were eligible. Analysis of these studies showed that, although the primary outcome of PDA closure on days two and five slightly favored bolus administration, there was no statistical difference between the two groups. The estimates for PDA closure were RR 1.57 (95% CI 0.54, 4.60), RD 0.10 (95% CI -0.13, 0.33) for day 2 and RR 2.77 (95% CI 0.33, 23.14), RD 0.15 (95% CI -0.13, 0.42) for day five. There was no statistical difference between the bolus and continuous groups for the secondary outcomes of reopening of PDA, neonatal mortality, intraventricular hemorrhage (IVH) and necrotizing enterocolitis (NEC). These analyses were based on a very small number of events reported by these trials. None of the trials reported on outcomes such as requirement for retreatment with indomethacin or surgical ligation, mortality, bronchopulmonary dysplasia (BPD), retinopathy of prematurity (ROP), neurodevelopmental outcome and isolated intestinal perforation. The review demonstrated that there was a decrease in cerebral blood flow velocity after bolus injections and that the difference between the bolus and continuous infusion groups remained significant for 12 - 24 hour. In one study (Christmann 2002), the decrease in blood flow was maximum at 10 minutes [MD -46.40 (95% CI -75.41, -17.39)], while the other study (Hammerman 1995) reported a maximum drop at 30 minutes [MD -55.60 (95% CI -62.92, -48.28)]. Similar decrease in blood flow to the renal and mesenteric circulations following bolus administration was reported in one study (Christmann 2002). In both of these circulations, the decrease was maximum 30 minutes after the bolus injection [typical estimates for renal and mesenteric circulations, respectively: MD -42.00 (95% CI -76.59, -7.41) and MD -26.50 (95% CI -45.34, -7.66)] and lasted about two hours. None of the trials detected predefined levels of decreased urine output and increased levels of BUN and creatinine.

AUTHORS' CONCLUSIONS

Due to a paucity of events and lack of precision, the available data was found to be insufficient to draw conclusions regarding the efficacy of continuous indomethacin infusion versus bolus injections for the treatment of PDA. Although continuous indomethacin seems to cause less alterations in cerebral, renal and mesenteric circulations, the clinical meaning of this effect is unclear. Definitive recommendations about the preferred method of indomethacin administration i.e. continuous versus bolus infusions for the treatment of PDA in premature infants cannot be made based on the current findings of this review.

Risk factors for persistent ductus arteriosus patency during indomethacin treatment

OBJECTIVE

To test the hypothesis that patent ductus arteriosus that fail to close with prostaglandin inhibition may be regulated by mechanisms that act independently of prostaglandin production.

STUDY DESIGN

We examined a cohort of 446 infants who were treated with indomethacin (within 15 hours of birth) to inhibit prostaglandin production. We used multiple logistic regression modeling to determine which perinatal/neonatal variables were most closely associated with the persistence of ductus patency in the presence of diminished prostaglandin production.

RESULTS

We identified 4 variables (immature gestational age, lack of exposure to antenatal betamethasone, severity of respiratory distress, and Caucasian race) that were significantly and independently associated with the degree of ductus patency.

CONCLUSION

Gestational age, antenatal glucocorticoid exposure, respiratory distress, and race are independent risk factors that appear to affect ductus closure even when indomethacin has been used to inhibit prostaglandin production. Future studies of these risk factors may identify new potential targets for patent ductus arteriosus treatment.

Pharmacologic, pharmacodynamic, and pharmacokinetic considerations with intravenous Ibuprofen lysine

Patent ductus arteriosus (PDA) is a common complication in preterm infants. An intravenous (IV) cyclooxygenase (COX) inhibitor is the pharmacotherapy of choice. Concerns over adverse effects associated with the traditional treatment, IV indomethacin, have led to the investigation of other COX inhibitors to assist closure of PDA. IV ibuprofen lysine is a COX inhibitor that demonstrates similar efficacy to indomethacin with few adverse effects. In addition, IV ibuprofen lysine does not cause reductions in cerebral, renal, and mesenteric blood flow that can be seen with indomethacin, and thus ibuprofen therapy is not associated with reduced renal function. Ibuprofen is primarily metabolized by cytochrome P450 (CYP) 2C9. The immaturity of neonatal biotransformation pathways has a pronounced effect on the pharmacokinetic parameters of ibuprofen, particularly because CYP2C9 enzyme activity is known to be very low at birth and to increase rapidly over the first several days of life. Ibuprofen is highly bound to albumin, raising concern that ibuprofen may displace bilirubin and subsequently increase free bilirubin concentrations. However, the ibuprofen concentrations achieved with approved dosing with IV ibuprofen lysine are lower than those expected to result in displacement of bilirubin and related adverse effects. Factors such as gestational age and CYP2C9 polymorphism may affect ibuprofen metabolism and therefore optimal dosing, but further clinical investigation is needed in these areas. Other areas for future investigation include prolonged dosing regimens, prophylactic administration, and alternate indications. At the approved dose, IV ibuprofen lysine is a safe, effective pharmacologic agent to promote closure of PDAs in preterm infants.

Prolonged versus short course of indomethacin for the treatment of patent ductus arteriosus in preterm infants

BACKGROUND

Indomethacin is a prostaglandin inhibitor used to treat patent ductus arteriosus (PDA) in preterm infants. Although indomethacin produces ductal closure in the majority of cases, it is ineffective in up to 40% of patients. Furthermore, the ductus will re-open in up to 35% of infants who initially respond to the drug. Prolonging the course of indomethacin has the potential to achieve higher rates of ductal closure.

OBJECTIVES

To determine the effect of a prolonged course of indomethacin (compared to a short course) on the rate of treatment failure without unwanted side-effects in preterm infants with PDA.

SEARCH STRATEGY

The search included review of personal files, abstracts of conferences, and the following electronic databases: MEDLINE (1966 to December 2006), EMBASE (1974 to December 2006), and Oxford Database of Perinatal Trials, Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 4, 2006). No language restrictions were applied.

SELECTION CRITERIA

Randomized or quasi-randomized controlled trials including preterm infants with PDA, diagnosed on clinical and/or echocardiographic examination that evaluated indomethacin treatment by any route given as a long course (four or more doses) vs. a short course (three or fewer doses) were included in the review. Trials needed to report on at least one of the following outcomes: failure of PDA to close, need for re-treatment, PDA re-opening, PDA ligation, mortality, duration of assisted ventilation, chronic lung disease (CLD), duration of supplemental oxygen dependence, intraventricular hemorrhage (IVH) (all and severe), diminished urine output, increased serum creatinine, necrotizing enterocolitis (NEC), bleeding diathesis, retinopathy of prematurity (ROP), and duration of hospital stay.

DATA COLLECTION AND ANALYSIS

The three review authors independently abstracted data from each study. Relative risk (RR) and Risk Difference (RD) with 95% confidence intervals (CI) using the fixed effect model for meta-analysis are reported. When a statistically significant RD was found, the number needed to treat (NNT) or number needed to harm (NNH) was also calculated with 95% CIs. The I squared statistic was used to test for heterogeneity of results among included trials.

MAIN RESULTS

Five trials met inclusion criteria and included 431 infants. Prolonged indomethacin treatment when compared to the short course did not result in a statistically significant difference in PDA closure, re-treatment, re-opening, or ligation rates. The prolonged course was associated with an increased risk of NEC [typical RR 1.87 (95% CI 1.07, 3.27); typical RD 0.08 (95% CI 0.01, 0.15); NNH 13 (7, 100)] and a decreased incidence of renal function impairment, as evidenced by a lower proportion of infants having diminished urine output [typical RR 0.27 (95% CI 0.13, 0.6); typical RD -0.19 (95% CI -0.28, -0.09); NNT 5 (4, 11)] and increased serum creatinine level [typical RR 0.51 (95% CI 0.33, 0.77); typical RD -0.14 (95% CI -0.23, -0.06); NNT 7 (4, 16)].

AUTHORS' CONCLUSIONS

Implications for practiceProlonged indomethacin course does not appear to have a significant effect on improving important outcomes, such as PDA treatment failure, CLD, IVH, or mortality. The reduction of transient renal impairment does not outweigh the increased risk of NEC associated with the prolonged course. Based on these results, a prolonged course of indomethacin cannot be recommended for the routine treatment of PDA in preterm infants. Implications for researchThere is a paucity of data on optimal dosing and duration of indomethacin therapy for the treatment of PDA, in particular for extremely low birth weight infants (ELBW) premature infants. It is likely that a single standard indomethacin regime is not the ideal for every premature infant. Therefore, individual patient response should be considered and evaluated, in particular in ELBW infants. Future randomized clinical trials should include this high risk population and investigate the effect of tailoring dose and duration of therapy to individual response in terms of echocardiographic findings and/or prostaglandin levels, focusing on clinically significant outcomes, including long-term neurodevelopmental outcomes. In addition, factors that may influence treatment effect, such as birth weight, gestational age, age at the time of randomization, total fluid intake, feeding practice, and severity of PDA, need to be taken into account when designing such studies.

Indomethacin decreases furosemide-induced natriuresis and diuresis on the neonatal kidney

Indomethacin is used to pharmacologically occlude patent ductus arteriosus in preterm infants. It induces renal untoward effects and furosemide is administered simultaneously to counteract them. The effect of furosemide is blunted by indomethacin. We analyzed comparatively the interactions of furosemide and indomethacin at the organic anion transport system in adult and newborn individuals. Adult and 5-day-old Wistar rats were allocated into three groups: (1) indomethacin (10 mg/kg, ip); (2) furosemide (2 mg/kg, ip); and (3) indomethacin/furosemide, at the same doses. Urinary flow, glomerular filtration rate (GFR), sodium and potassium fractional excretions, and free-water and osmolal clearances were estimated. Para-aminohippuric acid (PAH) uptake was measured in renal cortical slices to study the organic anion's secretory pathway. In adult and newborn rats, furosemide-induced increments in urinary fluxes and excretions of sodium and potassium were blunted by indomethacin administered simultaneously. PAH uptake was decreased to a further extent by indomethacin than by furosemide, suggesting that inhibition of the diuretic effect might be related to competition in the secretion of furosemide. Inhibitory interaction between indomethacin and furosemide was achieved at approximately 10-fold lower concentrations in the newborn than in the adult rats, suggesting that tubular secretion in the neonate is more sensitive to the action of these drugs than in the adult individual.

Pain control: non-steroidal anti-inflammatory agents

The non-steroidal anti-inflammatory drugs (NSAIDs) and acetaminophen (paracetamol) are the most common analgesic drugs used in neonates and infants despite limited pharmacodynamic data. Both drugs act through inhibition of cyclooxygenase enzymes. Neonatal acetaminophen clearance is reduced in premature neonates (0.7 L h(-1) x 70 kg(-1)) and increases to 5 L h(-1) x 70 kg(-1) at term (40% adult rates); adult rates are reached within the first year of life; NSAID clearance follows similar trends. Volume of distribution is increased in the neonatal period. Dosing of both drug groups is tempered by concerns about toxicity. Acetaminophen hepatotoxicity is less common in neonates than in older children and adults, possibly due to reduced oxidative enzyme activity (e.g. CYP 2E1). Data concerning NSAID adverse effects in the neonatal period are few. Renal function is reduced 20% after NSAID use for patent ductus arteriosus closure in premature neonates and there is no increased frequency of intraventricular haemorrhage. No significant difference in the change in cerebral blood volume, change in cerebral blood flow, or tissue oxygenation index was found between administration of ibuprofen or placebo in neonates. Future studies should define concentration-response relationships for these drugs that are age and pathology specific.

Determination of indomethacin in plasma by micellar electrokinetic chromatography with UV detection for premature infants with patent ducts arteriosus

A simple and selective micellar electrokinetic chromatography (MEKC) is described for determination of indomethacin in plasma. Plasma proteins are precipitated by acetonitrile. An aliquot of supernatant was evaporated and reconstituted with Tris buffer for MEKC analysis. The separation of indomethacin was performed at 25 degrees C using a background electrolyte consisting of Tris buffer (30 mM; pH 8.0) with 100 mM sodium octanesulfonate (SOS) as an anionic surfactant. Under this condition, a good separation with high efficiency and short analysis time is achieved. Several parameters affecting the separation of indomethacin were studied, including pH and concentrations of the Tris buffer and SOS. The linear range of the method for the determination of indomethacin was over 0.3-10.0 microg/mL; the detection limit (signal-to-noise ratio=3; injection 0.5 psi 5s) was 0.1 microg/mL. The proposed method for determination of indomethacin in premature infants with patent ducts arteriosus has been demonstrated.

Ontogeny of drug metabolizing enzymes in the neonate

Fetal exposure to xenobiotics is modulated to a considerable degree by the metabolic capabilities of the mother and the placenta. However, once liberated from the uterine environment the neonate is instantly exposed to a wide array of new macromolecules in the form of byproducts of cellular metabolism, dietary constituents, environmental toxins and pharmacologic agents. The rapid and efficient biotransformation of these compounds by Phase I and Phase II drug-metabolizing enzymes is an essential process if the infant is to avoid the accumulation of reactive compounds that could produce cellular injury or tissue dysfunction. Genetic polymorphisms and environmental factors are known to contribute dramatically to individual variation in the activity of drug-metabolizing enzymes. More recently, it has become apparent that programmed, developmental, regulatory events occur - independent of genotype - which further add to individual variation in drug metabolism. An appreciation of the impact of ontogeny on the expression and functional activity of the major drug-metabolizing enzymes enables the practicing clinician to predict the ultimate consequence of drug administration in the neonate to help guide optimal drug therapy.

Intravenous indometacin in preterm infants with symptomatic patent ductus arteriosus. A population pharmacokinetic study

AIMS

To characterize the population pharmacokinetics of indometacin in preterm infants with symptomatic patent ductus arteriosus and to investigate the influence of various factors on the response to treatment.

METHODS

Data were collected from 35 infants (gestational age 25-34 weeks; postnatal age 1-77 days) in neonatal units in Belfast and Copenhagen. Infants received an initial course of up to three doses of intravenous indometacin (0.1-0.2 mg kg(-1)) as considered appropriate by the treating physician. For those infants who did not respond to therapy or in whom the ductus reopened, a second course was sometimes given. Population analysis of the 185 plasma concentrations obtained was conducted using NONMEM and pharmacokinetic and demographic differences between responders and nonresponders were compared.

RESULTS

The concentration-time course of indometacin was best described by a one-compartment model. The final population parameter estimates of clearance (CL) and volume of distribution (V) (standardized to the median weight of 1.17 kg) were 0.00711 l h(-1) and 0.266 l, respectively. CL increased from birth by approximately 3.38% per day and V by approximately 1.47% per day. Concomitant digoxin therapy resulted in a 30% decrease in V. Interindividual variability in CL and V was 41% and 21%, respectively. Interoccasion variability for CL was 43%. Residual variability corresponded to a standard deviation of 0.148 mg l(-1). Closure occurred in 75% of infants with a plasma concentration > or = 0.4 mg l(-1) 24 h after the last dose.

CONCLUSIONS

Dosing regimens for indometacin should take into account the weight and postnatal age of the infant and any concomitant digoxin therapy. The population estimates can be used to determine typical values of CL and V allowing the prediction of individualized doses of indometacin that should increase the probability of achieving a 24 h plasma concentration > or = 0.4 mg l(-1). Although the pharmacokinetic estimates will be affected by both interindividual and within-individual variation, it is anticipated that this approach will decrease the variability of exposure and optimize treatment outcome.

Prolonged versus short course of indomethacin for the treatment of patent ductus arteriosus in preterm infants

BACKGROUND

Indomethacin is a prostaglandin inhibitor used to treat patent ductus arteriosus (PDA) in preterm infants. Although indomethacin produces ductal closure in the majority of cases, it is ineffective in up to 40% of patients. Furthermore, the ductus will re-open in up to 35% of infants who initially respond to the drug. A more prolonged course of indomethacin has been studied regarding the potential to achieve higher rates of ductal closure.

OBJECTIVES

To determine if a prolonged course of indomethacin (compared to a short course) reduces the rate of treatment failure in preterm infants with PDA without unwanted side-effects.

SEARCH STRATEGY

The search included review of personal files, abstracts of conferences, and the following electronic databases: MEDLINE (1966 to April 2003), EMBASE (1974 to April 2003), and Oxford Database of Perinatal Trials, Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 3, 2003). No language restrictions were applied.

SELECTION CRITERIA

1) DESIGN AND POPULATION: Randomized or quasi-randomized controlled trials including preterm infants with PDA diagnosed on clinical and/or echocardiographic examination.2) INTERVENTION: Indomethacin treatment by any route given as a long course (four or more doses) vs a short course (three or fewer doses). 3) OUTCOMES: Report of at least one of the following outcomes: failure of PDA to close, need for re-treatment, PDA re-opening, PDA ligation, mortality, duration of assisted ventilation, chronic lung disease (CLD), duration of supplemental oxygen dependence, intraventricular hemorrhage (IVH) (all and severe), diminished urine output, increased serum creatinine, necrotizing enterocolitis (NEC), bleeding diathesis, retinopathy of prematurity (ROP), and duration of hospital stay.

DATA COLLECTION AND ANALYSIS

The three reviewers independently abstracted data from each study. Relative risk (RR) and Risk Difference (RD) with 95% confidence intervals (CI) using the fixed effect model for meta-analysis are reported. When a statistically significant RD was found, the number needed to treat (NNT) or number needed to harm (NNH) was also calculated with 95% CIs. A chi-square test was used to test for heterogeneity of results among included trials.

MAIN RESULTS

Prolonged indomethacin treatment when compared to the short course resulted in a borderline statistically significant difference in PDA re-opening rate favoring the prolonged course [RR 0.54 (95% CI 0.3, 0.99); RD -0.12 (95% CI -0.24, -0.01); NNT = 8 (4, 100). There was no statistically significant treatment effect on PDA closure, re-treatment, or ligation rates. The prolonged course was associated with a decreased incidence of severe IVH [RR 0.49 (95% CI 0.25, 0.98); RD -0.12 (95% CI -0.24, -0.01); NNT 8 (4, 100)] and renal function impairment, as evidenced by a lower proportion of infants having an increased creatinine level [RR 0.52 (95% CI 0.34, 0.81); RD -0.20 (95% CI -0.33, -0.08); NNT 5 (3, 13)]. However, there was a trend for the prolonged course to increase the proportion of infants with CLD in the one trial reporting this outcome [RR 2.24 (95% CI 0.98, 5.12); RD 0.24 (95% CI 0.01, 0.47)].

IMPLICATIONS FOR PRACTICE

Prolonged as compared to short course of indomethacin for the treatment of PDA in preterm infants has a borderline effect on reducing the rate of PDA re-opening and it may be associated with an increased risk for CLD. However, prolonged course of indomethacin appears to reduce the risk of severe intracranial hemorrhage and renal impairment in this population. Definitive recommendations about the preferred duration of indomethacin therapy, i.e. prolonged versus short course, for the treatment of PDA in premature infants cannot be made based on the current findings of this review.

IMPLICATIONS FOR RESEARCH

There is a paucity of data on optimal duration of indomethacin therapy for the treatment of PDA, in particular for ELBW premature infants. Future randomized clinical trials should include this high risk population and investigate the premature infants. Future randomized clinical trials should include this high risk population and investigate the possibility of tailoring duration of therapy (prolonged versus short) to individual response in terms of echocardiographic findings and/or prostaglandin levels, focusing on clinically significant outcomes and potential complications associated with either strategy. In addition, factors which may influence treatment effect need to be taken into account when designing such studies.