Resolution of opioid-induced postoperative ileus in a newborn infant after methylnaltrexone Lars Garten a, ⁎ , Petra Degenhardt b , Christoph Bührer a a Department of Neonatology, Charité University Medical Center, Berlin, Germany b Department of Pediatric Surgery, Charité University Medical Center, Berlin, Germany Received 2 September 2010; revised 27 September 2010; accepted 17 October 2010 Key words: Bowel dysfunction; Newborn; Opiate μ-receptor antagonist; Abdominal surgery Abstract Transient impairment of bowel function is a frequent and distressing problem in neonates on opioid-induced analgesia. Methylnaltrexone, a peripheral-acting μ-opioid receptor antagonist, has been studied in adults for the treatment of opioid-induced constipation in advanced illness and has been suggested as a promising therapeutic concept for reducing postoperative ileus. Here, we report on a newborn infant on fentanyl analgesia after major abdominal surgery with aggravated ileus. After 8 days of quiescent bowel, the patient's intestinal dysmotility resolved within 15 minutes after intravenous administration of methylnaltrexone (0.15 mg/kg body weight). Methylnatrexone was repeated daily until cessation of fentanyl administration. There were no signs of pain or opioid withdrawal. © 2011 Elsevier Inc. All rights reserved. Opioids are the treatment of first choice for moderate-to- severe pain in neonates. They frequently inhibit bowel movements predominantly mediated by gastrointestinal μ- receptors [1,2]. As a result, transient impairment of bowel function is a frequent and distressing problem in neonates on opioid analgesia. After open abdominal surgery, neonates who are on opioid analgesia are at particularly high risk for developing postoperative paralytic ileus. Selective blockade of the peripheral μ-receptors is a logical therapeutic target for managing opioid-induced impairment of bowel function without compromising centrally mediated effects of opioid analgesia or precipitating withdrawal. Methylnaltrexone is a peripheral opioid receptor antago- nist that has restricted ability to cross the blood-brain barrier because of its polarity and low lipid solubility. Methylnal- trexone has been extensively studied in adults for the treatment of opioid-induced constipation in advanced illness [3-6]. In its subcutaneous form, methylnaltrexone has been approved both by the US Food and Drug Administration and the European Medicines Agency for treatment of opioid- induced constipation in adult patients on palliative care for end-stage disease. In addition, several reports indicate that peripheral opioid receptor antagonism could also be a promising therapeutic concept for reducing postoperative ileus [7-9]. This is, to our knowledge, the first report on the use of methylnaltrexone in a newborn infant aimed at treating opioid-induced postoperative ileus. 1. Case report A female newborn infant (birth weight, 3170 g; 40 weeks gestational age) with a prenatally diagnosed aortic arch ⁎ Corresponding author. Klinik für Neonatologie, Charité Universitäts- medizin Berlin, Augustenburger Platz 1, D-13353 Berlin, Germany. Tel.: +49 30 450566122; fax: +49 30 450566922. E-mail address: lars.garten@charite.de (L. Garten). www.elsevier.com/locate/jpedsurg 0022-3468/$ – see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.jpedsurg.2010.10.015 Journal of Pediatric Surgery (2011) 46, E13–E15