Patent ductus arteriosus (PDA) affects approximately 31% of infants whose birth weight is between 501 and 1500 g. The ductus arteriosus is a blood vessel that allows blood to bypass the pulmonary vasculature in utero. Oxygen delivery and elimination of prostaglandins are essential for the closure of the ductus after birth. For years, indomethacin has been the drug of choice for the treatment of PDA in the USA. Undesirable adverse effects prompted researchers to seek alternative agents. In April 2006, the US Food and Drug Administration approved the use of ibuprofen lysine (NeoProfen) for closure of clinically significant PDA in premature neonates. Ibuprofen’s mechanism of action for closure of PDA is believed to be through the inhibition of prostaglandins. Clinical studies have shown ibuprofen to be as effective as indomethacin with fewer adverse effects. The ductus arteriosus is a blood vessel that connects the pulmonary artery to the aorta. In utero, blood is shunted away from the lungs due to higher pulmonary resistance. Hence, blood exits the right ventricle, moves through the ductus arteriosus, and enters into the aorta. By 6 weeks’ gestation, the amount of blood flowing through the ductus arteriosus is approximately 50% to 60% of total cardiac output. Prostaglandins are potent vasodilators that keep the ductus arteriosus open in utero. Normally, pulmonary resistance begins to drop when oxygenation and ventilation occur after birth. Blood enters the pulmonary circulation, which delivers prostaglandins to the lungs, where they are metabolized and cleared. Oxygenated blood also plays a major role in the closure of the ductus arteriosus. Functional closure occurs in the majority of term neonates by 9 to 12 hours after birth. Risk factors for patent ductus arteriosus (PDA) include prematurity and the presence of respiratory distress syndrome (1). The incidence of PDA is approximately 31% in neonates whose birth weight is between 501 and 1500 g (1, 2). PDA causes left-to-right shunting, which increases the risk of intraventricular hemorrhage (IVH), bronchopulmonary dysplasia, congestive heart failure, and necrotizing enterocolitis (NEC) (1, 3).