Sodium chloride injection to treat opioid overdose; Does it work? A preclinical study

Opioid overdoses (ODs) are increasing in Mexico's northern border. Because naloxone is usually not available, witnesses inject common salt (NaCl) into a vein of OD victims in an attempt to help them regain consciousness. Despite this widespread practice, no preclinical studies have addressed the efficacy of NaCl as an opioid antidote. Here we tested saline solutions at different concentrations. Because the highest (31.6 %) caused tail necrosis, we selected 17.7 % as a hypertonic saline solution (HSS) to determine if it could prevent the lethal effect of morphine (Mor), fentanyl (Fen), or Mor + Fen in adult Wistar male rats. We also evaluated if NaCl could modify the opioid antagonist effect of naloxone. Our results show that HSS: a) sensitizes animals to thermal but not mechanical stimuli; b) does not prevent mortality caused by high morphine or fentanyl doses; c) decreases the latency to recovery from the sedative effects caused by low doses of morphine or fentanyl; and d) increases naloxone's efficacy to prevent the lethality produced by Mor or Fen, but not by Mor + Fen. These results suggest that HSS is marginally effective in shortening the recovery time from nonfatal opioid ODs and increases naloxone's efficacy to counteract opioid-induced ODs.