Which of the following pharmaceutical agents acts as a pure opioid receptor antagonist ?
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Answer: A. Natrexone
Explanation
Naltrexone functions as a pure competitive opioid receptor antagonist. It binds firmly to opioid receptors without triggering any intrinsic agonist activity. This blockade prevents exogenous opioids from binding and producing euphoric effects. Antagonists block receptor sites to prevent activation by agonists or natural neurotransmitters. Naltrexone has high oral bioavailability and a long duration of therapeutic action. Rehabilitation programs utilize antagonist therapy to support long-term abstinence goals.
Physicians prescribe naltrexone to manage both alcohol and opioid dependence disorders. Patients must be completely opioid-free before starting naltrexone to avoid precipitated withdrawal. Pharmacotherapy plays a vital role in comprehensive addiction medicine treatment plans. Nalbuphine is a mixed agonist-antagonist opioid used for moderate to severe pain management. Butorphanol exhibits agonist-antagonist properties and is often used in obstetric anesthesia. Pentazocine acts as a partial agonist-antagonist with established analgesic properties.
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