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How long does Bunavail (buprenorphine/naloxone) last?

Medically reviewed by Carmen Pope, BPharm. Last updated on Nov 8, 2023.

Official answer


Note that the brand Bunavail has been discontinued but generic equivalents are available under the name buprenorphine/naloxone. We have kept a record of this question for interest purposes only.

  • The effects of Bunavail may last for up to three to four days, depending on a person’s weight, presence of liver disease, or history of drug abuse
  • Bunavail has a half-life of 16 to 27 hours which means it can take several days until levels of Bunavail are low enough to precipitate withdrawal symptoms, and up to six days for Bunavail to be totally eliminated from the body
  • Bunavail is usually dosed once a day; however, in some cases, it may be dosed every second day or a few times a week.

Bunavail contains buprenorphine and naloxone and it is usually taken once a day. It is one of many medicines available that treat the withdrawal symptoms and drug cravings that occur during opioid withdrawal.

Bunavail is available as a buccal film which is placed in the mouth between your gum and inner cheek.

Buprenorphine, the active ingredient, is quickly absorbed after taking by mouth and reaches its peak effect within three to four hours.

Bunavail has a long half-life of 16.4 to 27.5 hours. A drug’s half-life is the time it takes for half of a dose to be eliminated from the body. Generally, it takes four to five half-lives for a drug to be considered totally eliminated from the body, which is 82 to 137 hours, or 3.4 to 5.7 days. However, the effect of Bunavail can wear off much sooner.

Bunavail's effects at blocking opioid receptors last for at least 24 hours, which is why it is given once a day. However, it actually stays bound to opioid receptors for about three days, which means that it can be dosed every other day or sometimes twice weekly.

The actual length of time its effect lasts for varies among individuals depending on their weight, presence of liver disease, or history of drug abuse. In some people, the effects of Bunavail may last up to three or four days.

How does Bunavail work?

Bunavail contains buprenorphine and naloxone.

Buprenorphine is an opioid (narcotic) that has a unique and complex mechanism of action, which includes incomplete binding to "mu" opioid receptors and complete binding to "kappa" opioid receptors.

Opioid receptors have three main effects:

  • Decreasing pain
  • Reducing breathing (respiratory depression)
  • Producing euphoria (feelings of intense happiness or excitement).

The way buprenorphine binds means it can satisfy opioid cravings without producing strong feelings of euphoria or causing significant respiratory depression. Also, while it is bound to opioid receptors, other opioids (such as heroin or oxycodone) cannot bind. It also stays on the receptors for longer - about three days; which makes it a good choice for use in opioid addiction treatment programs.

Naloxone is present in this combination tablet to discourage misuse. Naloxone is a very strong blocker of "mu" opioid receptors and will precipitate people into opioid withdrawal if drug misusers attempt to convert the product into an injectable form. Naloxone has poor absorption when taken sublingually.

Bunavail belongs to the class of medicines known as combination opioid/opioid antagonists.


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