A female in labor ward was administered opioid analgesic. Which of the following drugs should be kept ready for emergency?

Naloxone is an opioid anatagonist given intravenously. It blocks mu, kappa and delta receptors. It is the DOC for opioid toxicity. Lignocaine is a local anaesthetic. Diphenhydramine is a first generation antihistaminic. Fentanyl is a synthetic opioid.