In some countries, ibuprofen lysine (the lysine salt of ibuprofen, sometimes called "ibuprofen lysinate") is licensed for treatment of the same conditions as ibuprofen; the lysine salt is used because it is more water-soluble.
Ibuprofen lysine is sold for rapid pain relief; given in the form of its lysine salt, absorption is much quicker (35 minutes for the salt compared to 90120 minutes for ibuprofen). However, a clinical trial with 351 participants in 2020, funded by Sanofi, found no significant difference between ibuprofen and ibuprofen lysine concerning the eventual onset of action or analgesic efficacy.
In 2006, ibuprofen lysine was approved in the US by the Food and Drug Administration (FDA) for closure of patent ductus arteriosus in premature infants weighing between , who are no more than 32 weeks gestational age when usual medical management (such as fluid restriction, diuretics, and respiratory support) is not effective.