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How long does Bunavail block opiates?

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.

  • Bunavail may block opiates for up to three to four days
  • 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 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 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.

The buprenorphine component of Bunavail blocks opiates. It works by binding to the opiate receptors in your brain, preventing other opioids from being able to attach. Because it has low opioid activity it does not cause a significant “high”.

The naloxone component is there to discourage misuse of Bunavail, as this will cause people to experience uncomfortable withdrawal symptoms if they try and inject Bunavail.

How long does Bunavail last in the body for?

The buprenorphine component of Bunavail is quickly absorbed after taking by mouth and reaches its peak effect within three to four hours.

It 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 for Bunavail, is 82 to 137 hours, or 3.4 to 5.7 days.

However, the effect of Bunavail can wear off much sooner. Its effects at blocking opioid receptors last for at least 24 hours, which is why it is given once a day. However, it usually takes three or more days until the levels of Bunavail are low enough to cause withdrawal symptoms, which means that it can be dosed every other day or sometimes twice weekly.

The actual length of time its effects last for varies among individuals depending on their weight, presence of liver disease, or history of drug abuse.

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 tablet into an injectable form.

Naloxone has poor absorption when taken sublingually.

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

How do you use Bunavail buccal film?

Bunavail is a combination buccal film containing buprenorphine and naloxone.

The strips are bi-layered with a medication side and a backing to prevent swallowing the strip. Because of this delivery system, more medication is absorbed directly into the bloodstream, rather than being swallowed. To use Bunavail buccal film:

  1. Wet the inside of the cheek with the tongue.
  2. Apply the side that has the active ingredients (this will be marked BN2, BN4, or BN6) to the wet area and hold in place for 5 seconds. The strip should stick upon contact.
  3. The backing of the strip ensures nearly all the Bunavail is absorbed into the bloodstream, through the cheek. The strip has a citrus-blend flavor.
  4. The time that it takes for each strip to dissolve varies depending on strength, but it is usually within 15 to 30 minutes.
  5. You should not eat or drink while the strip is dissolving; however, you can still talk while it is in place.
  6. There should be no residual film to remove afterward; however, if any is remaining after 30 minutes, you can remove it from your mouth.

Coadministration with liquids reduced the absorption of buprenorphine by 59% and naloxone, by up to 76%, which is why the film should be allowed to dissolve in the mouth without water or food.


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