Naloxone 0.4 mg to 2 mg IV Sometimes endotracheal intubation Patients with spontaneous respirations can be treated with an opioid antagonist, typically naloxone 0.4 mg to 2 mg IV (for children < 20 kg, 0.1 mg / kg); naloxone has no agonist activity and a very short half-life (see table Symptoms and Treatment of Specific Poisons).