Subutex 

is the less widely used of two buprenorphine formulations available to opiate pharmacotherapy consumers in Victoria, (Suboxone being the other). 

Subutex is a mono-formulation of buprenorphine available in 0.4, 2 & 8mg sub-lingual tablets. It was the first buprenorphine product to become available in Victoria, but has been largely superseded by Suboxone (a buprenorphine/naloxone formulation.) The presence of the opiate antagonist naloxone in Suboxone makes it less attractive than Subutex to clients who may wish to divert their dose with intention of injecting it. Because of the harms associated with this practice, doctors are less willing to prescribe Subutex and take away doses are only available in a handful of circumstances.

Subutex tablets are placed beneath the tongue, where they are absorbed directly into the blood-stream through the mucous membrane.

Clients on low doses sometimes find Subutex preferable because the 0.4mg tablet can allow for more accurate dosing.

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Basic Pharmacology of Buprenorphine

Buprenorphine is a partial opioid agonist. It binds strongly to the same receptors as other opiates, but stimulates them only weakly, producing very little of an opiate effect.

Once the buprenorphine molecule is locked onto the receptor, it remains there much longer than other opiates like heroin and methadone. If such drugs are taken while on buprenorphine, their effects will be much reduced.

Buprenorphine’s affinity for the receptor is powerful enough to displace opiates like heroin and methadone. For this reason, the initial dose of buprenorphine should be low (i.e. < 8mg) and, ideally, the client should be in the first stages of opioid withdrawal. If a dependent client takes a large dose of buprenorphine after recent use of heroin – or before the onset of withdrawal – the buprenorphine can precipitate immediate and full withdrawal. This is an extremely unpleasant, uncomfortable experience to be avoided at all cost.

 

The Ceiling Effect

An interesting feature of buprenorphine is its ceiling effect.

Up to a certain point, the more buprenorphine that is taken, the greater the opiate effect. Past that point, increasing the dose only results in a longer duration of action and no increased opiate effect. This means that some people can have their daily dose increased (usually doubled) and the dose will last for two days instead of one. This can be very useful for those who have difficulty reaching their dosing points, and can remove the need for take aways during the first month of treatment.

Though scientific evidence is scant, this ceiling effect presumably varies with the individual. The maximum allowable dose of buprenorphine is 32mg.

 

Injecting Subutex

If another opiate – like heroin, methadone or oxycodone – is present in the system when Subutex is injected, precipitated withdrawal may result, as the opioid will be rapidly displaced from opiate receptors by the buprenorphine.

Injecting Subutex carries serious health risks and is not recommended. If the medication is removed from the mouth prior to injection, these risks are compounded. For more information about the harms associated with injecting Subutex, please contact PAMS.

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Take Away Doses of Subutex

There are no routine take away doses of Subutex, unless the consumer is:

• Pregnant and/or breast-feeding

• Has a documented allergy to the naloxone (present in Suboxone).

• Is on a dose of <2mg (this because a 0.4mg tablet of buprenorphine is available, but not in the combined buprenorphine-naloxone (Suboxone) formulation.

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If a person meets any of the above criteria, take away doses may be provided if the prescriber assesses the client as being stable and there are no other issues of concern.

If you have any questions or want to discuss your individual situation, please contact PAMS PH: 1800 443 844.