Withdrawal Versus Precipitated Withdrawal

Habitual opioid users become dependent on opioids. Dependent individuals who stop or decrease opioid use may go into spontaneous withdrawal. Dependent individuals who take an opioid antagonist (or partial agonist, in some cases) may go into precipitated withdrawal.

• Withdrawal occurs when a physically dependent individual suddenly stops or significantly decreases opioid usage.

  The time frame for withdrawal is heavily dependent on the half-life of the drug being taken. Withdrawal from heroin, an opioid with a relatively short half-life, is fairly quick and very intense. Heroin withdrawal typically begins 6 to 12 hours after the last dose, peaks between 36 and 72 hours, and lasts about 5 days. It may be several months before the patient feels completely "normal" again. As a rule, withdrawal from opioids with longer half-lives, such as methadone or buprenorphine, has a later onset, is more protracted, and features less intense symptoms.

• Precipitated withdrawal occurs when a full agonist, such as heroin, is displaced from opioid receptors by an antagonist, such as naloxone. Precipitated withdrawal is similar to regular withdrawal but is more intense and has a much faster onset.

  In some cases, a partial agonist, such as buprenorphine, can precipitate withdrawal. Buprenorphine is more likely to precipitate withdrawal if

  • The patient has a high level of physical dependence.
  • There has been a short time interval between the last dose of the full agonist and the first dose of buprenorphine.
  • A high dose of buprenorphine is used.
  • The full agonist has a long half-life, as is the case with methadone.