Final answer:
Naloxone is the drug that can reverse the respiratory depression caused by opioids such as morphine, quickly restoring normal respiratory function in emergency situations.
Step-by-step explanation:
A postoperative client who has been receiving morphine for pain management is exhibiting a depressed respiratory rate and is not responsive to stimuli. The drug that has the potential to reverse the respiratory-depressant effect of an opioid such as morphine is naloxone. Naloxone is an opioid antagonist that quickly reverses the effects of opioids by binding to the opioid receptors in the brain, thereby blocking the action of the opioids. This reversal includes the restoration of normal respiratory function in cases of opioid overdose. Naloxone's administration is typically parenteral, and while it has a short duration of action, it is crucial in emergency situations to prevent fatal respiratory depression due to opioid overdose.