Consumption of Movantik™ (Naloxegol) results in detection of naloxone in the patient's urine evaluated by confirmatory urine drug testing

Background: Many patients on chronic opioid therapy suffer from constipation, one of the most common side effect of opioids. Movantik (TM) (naloxegol) is an opioid antagonist that is recently introduced in the market to treat opioid-induced constipation and contains naloxegol as the active ingredient. Naloxegol is a pegylated (polyethylene glycol-modified) derivative of alpha-naloxol. Detection of naloxone in the patients urine after consumption of naloxegol was not reported by the manufacturer and may mislead the prescribing clinicians. This study was conducted to investigate the presence of naloxone in the urine of patients that consume movnatik in pain management clinics. Methods: The presence of naloxone and naloxol in the urine of 45 patients that consumed naloxegol and 25 patients that consumed suboxone (TM) were investigated using a liquid chromatography mass spectrometry (LCMS) method. The urinary concentration of naloxone, naloxol, and their glucuronide conjugates were evaluated in five volunteers that took one pill of naloxegol for one day and one volunteer who took the pill for three days. Results: Naloxone was detected in the urine of 45 individuals that were prescribed naloxegol. Urinary concentration of naloxone showed a distribution with a mean of 25 +/- 18 ng/ml. Consumption of one pill of 25 mg naloxegol resulted in the detection of naloxol and naloxone in the urine of 5 volunteers 1 h after taking the pill. Evaluation of urine specimens from 25 patients that consumed suboxone (TM), resulted in the detection of naloxone (180 +/- 187 ng/ml) and naloxol (6.3 +/- 7.2 ng/ml). Conclusions: This study demonstrated that consumption of naloxegol leads to appearance of naloxone in the urine of patients receiving opioid therapy in pain management clinics.