Buprenorphine (e.g. Temgesic®, Subutex®, Suboxone®, Buprenaddict®, Buprenorphin Sanofi®, Espranor®) is a semi-synthetic opioid and a potent analgesic. It is a prescribed medication with weaker opioid agonist activity than methadone. Unlike methadone or heroin, buprenorphine does not give patients the feeling of “being wrapped in cotton wool” but leaves their minds clear. Buprenorphine is not well absorbed and has a poor bio-availability due to the liver first pass- effect if taken enterally and the usual route of administration in treating opioid dependence is therefore sublingual. Recently, subcutaneous buprenorphine depot injections (Buvidal®, FluidCrystal technology) for weekly or monthly application and buprenorphine implants (Sixmo®) have been approved by the European Medicine Agency EMA. With increasing doses of buprenorphine, the opioid effect reaches a plateau. Consequently, buprenorphine is less likely than either methadone or heroin to result in opioid overdose, even when taken with other opioids at the same time. The effectiveness of buprenorphine is similar to that of methadone at adequate doses, in terms of reduction in illicit opioid use and improvements in psychosocial functioning. However, buprenorphine may be associated with lower rates of retention in treatment. Buprenorphine is currently more expensive than methadone.
Buprenorphine is acceptable to heroin users, has few side effects and is associated with a relatively mild withdrawal syndrome. When used in opioid substitution therapy for pregnant women with opioid dependence, it appears to be associated with a lower incidence of neonatal withdrawal syndrome.
The main disadvantage of sublingual buprenorphine therapy in the prison setting is that because it can take between five and ten minutes for the tablet to be absorbed sublingually, there is a risk of removal and subsequent sale. Experience shows that such a practice can place the user who is prescribed such medication at risk of harassment and bullying to remove their medication. Some prisons practitioners will crush the medication prior to administering as there is no evidence that crushing alters the bioavailability of the drug. In many prisons, the consumption of buprenorphine is directly observed. However, such a practice is very labour intensive due to the time taken for the drug to be absorbed sublingually and therefore the prescribing of combination of naloxone and buprenorphine is becoming more widespread in prisons as an alternative.
In some countries Espranor® (lyophilisate in tablet form) is being authorized. It is a tablet containing buprenorphine that is administered on (not under) the tongue and dissolves rapidly. According to the manufacturer it should take about 15 seconds for the tablet to dissolve on the tongue. It is used in MAT of opioid-dependent individuals. Espranor® should be available as lyophilisate tablets containing 2 mg or 8 mg of buprenorphine.
Lyophilisates are solid preparations that are dissolved either directly in the mouth or in water before administration. They are produced by freeze-drying (lyophilisation). The advantages lie in rapid absorption via the oral mucosa and the absence of any first-pass effect, which means that lower doses may be possible.
A combination product of buprenorphine with a small amount of naloxone (4:1 ratio) has been developed to reduce potential diversion and misuse. Naloxone is poorly absorbed sublingually, which limits its pharmacologic effect. However, if the tablet is crushed and used intravenously by an opioid-dependent person, the naloxone is bio-available and can precipitate severe opioid withdrawal, which can potentially deter further such abuse by this route. The recent approval of subcutaneous buprenorphine depot injections by the EMA provides another alternative to sublingual buprenorphine substitution therapy, particularly in the prison setting and during the Covid-19 pandemic (Scottish Government, 2020)