What is the primary antidote for opioid overdose?

Naloxone is the primary antidote for opioid overdose because it is an opioid antagonist that works by blocking the effects of opioids at the receptor sites in the brain. This action counteracts the life-threatening respiratory depression and sedation caused by opioid overdose. Naloxone is administered quickly and can reverse the effects of narcotics within minutes, making it crucial in emergency situations where a person is suspected of having overdosed on opioids. Its use has been a standard in managing opioid-related emergencies, as it effectively restores normal respiratory activity and consciousness.

Other options mentioned do not serve as antidotes for opioid overdoses: dextrose is used in cases of hypoglycemia, flumazenil is primarily a benzodiazepine antagonist and not indicated for opioid overdoses, and calcium gluconate is used to treat cases of hypocalcemia or magnesium toxicity. Therefore, specifically for opioid overdose, naloxone stands out as the vital and most appropriate intervention.