Subutex/Suboxone

Pharmacology

Buprenorphine has both opiate agonist and antagonist properties. Opiates latch onto receptors on nerve cells. In doing this they displace and over time replace the indigenous endorphins. Some opioids stimulate the receptors (agonists), some occupy and block action at the receptor site (antagonists), while a third group can do either, depending on what is happening at the receptor on contact. We call this third group partial agonists or agonist/antagonists and buprenorphine falls into this category.

Buprenorphine (Subutex) itself binds more strongly to receptors in the brain than do other opioids, making it more difficult for opioids to act at the relevant sites when buprenorphine is in the system. Interestingly, while methadone's effectiveness is generally thought to increase with dose (certainly up to 120mgs for maintenance, although most patients will not require this dose), buprenorphine has a ceiling effect at 32 mg, meaning that higher doses provide little or no extra benefit.

It is often considered that Suboxone/ Subutex is less stigmatised than methadone. It is probably fair to assume the drug formulations are identical, if taken as prescribed, that is not crushed for injecting, snorting or smoking. While the first day or two may be difficult, most patients are stabilized by the second day and these products are even longer acting than methadone, so may not require daily dosing and missing a day is less problematic. Side effects, such as sweating, fatigue and constipation are often less marked than with methadone. Suboxone is however not for everyone and may not fully satisfy cravings or block withdrawal symptoms for those with very high tolerances.

Good guidance is published by The Royal College of General Practitioners on Buprenorphine and it seems both from this source and anecdotally that patients on higher doses of heroin can transfer straight from street heroin more effectively than might be supposed given the caution on dosing with methadone change overs. The delay before initiating should be at least 12-18 hours with heroin and 24 hours since the last dose of methadone, however if the person is clearly in withdrawal it should be assumed that starting buprenorphine will not exacerbate the condition and make matters worse. There will be considerable inter-person variation.