Buprenorphine-naloxone (Suboxone) is prescribed for a patient with opioid use disorder. The naloxone component is included primarily for which reason?
- A To accelerate the onset of buprenorphine's analgesic action
- B To deter parenteral misuse, since naloxone has poor sublingual bioavailability but will precipitate withdrawal if injected ✓
- C To provide additional mu-opioid receptor blockade beyond that of buprenorphine alone
- D To prevent constipation caused by buprenorphine
Correct answer: B. To deter parenteral misuse, since naloxone has poor sublingual bioavailability but will precipitate withdrawal if injected
Explanation
Naloxone has very low sublingual and oral bioavailability, so when Suboxone is taken as prescribed sublingually, the naloxone component has essentially no clinical opioid-antagonist effect and buprenorphine acts as the active agent. However, if the tablet is crushed and injected, naloxone becomes bioavailable intravenously, precipitates acute opioid withdrawal in a dependent user, and removes any euphoric effect, thereby deterring diversion and injection misuse. This formulation design is a harm-reduction strategy rather than a therapeutic combination.
Reference: Kaplan & Sadock's Synopsis of Psychiatry, 11th ed.
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