10 April 2011

Eric Strain talks about the buprenorphine film.

“Clinical Advances in the management of opiate dependence”

Friday 11th March & Saturday 12th March, 2011. Intercontinental Hotel, Sydney.

“Suboxone Sublingual Film - the US Experience”

Organised by the Reckitt Benckiser company.

While this conference had been billed initially as an update in opioid pharmacotherapies, there were rumours around that it was actually a product launch. Indeed, the first power-point slide stated: "Suboxone Sublingual Film - the US Experience". Professor Eric Strain’s presentation kicked off the first of two papers on the Friday afternoon after a delightful luncheon in the Café Opera provided by the company. I first heard about a mooted wafer version of buprenorphine numerous years ago and was surprised to find that it is now being approved in Australia.

Drug research guru Eric Strain from Johns Hopkins in Baltimore spoke to an audience of about 80 doctors from around Australia and overseas who were welcomed by meeting chair Dr Sue Ballantyne from Brisbane. Unlike most such national and international meetings, I understand that the entire event, travel, meals, transfers and accommodation were all funded by the manufacturer. Indeed, one had the feeling that this was closer to advertising a new product than a balanced educational session.

Dr Strain said that in response to reports of childhood poisonings, slow dissolution, diversion, (*see stop-press below) and other problems with Suboxone sub-lingual tablets, the film version was developed. There were three main pieces of evidence supporting the ‘film’ (or wafer) … initially there were trials in volunteers of the film with pharmacological data measuring absorption - these were part of the registration process but have not been published. We were shown graphs of detailed blood levels, where the films were substantially better absorbed than the buprenorphine tablets with which they were compared. From the graphs we were shown, the levels in the hours after administration appeared to be consistently 20 - 28% higher in subjects given the films versus tablets. Then we were told of some strangely contradictory clinical research work showing that patients who were transferred to the ‘film’ version noted less effect from the film formulation, despite the higher levels in the parallel studies on non-addict volunteers. This was just one of numerous worrying inconsistencies in the field revealed on the day.

We were told that the combination version with naloxone has been approved in the US for about six months and I recall Dr Strain saying that it has now taken a large market share (50% or more in some areas, if I heard correctly).

The speaker then described his own trial in some detail, including the rationale for performing it, something which is not made clear in the article itself. It examined withdrawal symptom indices during the initiation period in two groups taking (1) pure buprenorphine films and the (2) combination film. Performed in volunteers, it showed no difference, although of course this does not prove that they are equivalent. Dr Strain explained that the need for the trial was the [allegedly unfair and inappropriate] FDA requirement under the long-standing US treatment guidelines that patients should be stabilised on pure buprenorphine and only transferred to the combination product later if appropriate (and never in pregnant or potentially pregnant women). He told the audience that few American doctors actually followed this rule and that the Reckitt company was actively fighting to have the provision removed by the FDA. To my mind the use of pure buprenorphine in new patients is just logical, just as with insulin, warfarin, cortisone or lithium. There may be other commercial implications but these should be secondary to good therapeutics. His study in essence showed what he wanted: that there was no significant difference in induction withdrawals between pure and combination product, something one could have predicted.

[Comment by AB: I can see why the company might be pressing for this sort of research to be done, yet it would seem to be a low priority clinically when there are so many unknowns in the field. It seems odd that an august institution like Johns Hopkins Medical Center would follow commercial considerations to this extent. As just one example, to date there has still been no simple ‘head to head’ comparison of the combination product against pure buprenorphine despite strong but unsubstantiated contentions from some quarters that they are the same. One non-blinded trial showed that stable patients sought 50% higher doses when transferred to the combination product (Bell et al.). The work that Dr Strain discussed at this very conference indicates that absorption is also affected by other constituents. Nor has there been any research to my knowledge on the important matter of patient matching, except by ‘trial and error’ which is hardly scientific.

Equally, there has been no persuasive community evidence produced to suggest that the combination product is any less likely to be abused or diverted than the pure product. Its parallel (pure) product for analgesia was widely abused in New Zealand according to Robinson’s report in D&A Dependence in 1991 (ref below). After nation-wide replacement of pure buprenorphine with the combination version (but with three times as much naloxone per mg) the subjects attending an addiction clinic who used/abused buprenorphine had dropped from 81% to 64%. This is a modest reduction indeed, especially considering the claims by some that naloxone inclusion reduces injecting substantially. At the same time Robinson reported that pharmaceutical morphine use increased from 68% to 86% (and morphine is a much more dangerous drug when used without supervision). Buprenorphine was subsequently withdrawn altogether in New Zealand and not reintroduced for almost 20 years. End of ‘editorial’!]

Dr Strain told the audience that the new formulation came in individual packs which were peeled open to reveal their contents which was a square or rectangle of gel-film which was then inserted by the patient under their tongue. It was hard to remove manually as it quickly merged with the buccal mucosa. Dr Strain went into some detail about why pink/orange was chosen to match the Suboxone tablets (he was surprised to learn from a delegate sitting nearby that in Australia Suboxone is not orange but white). The company may not know that in Australia the drug is often supervised (the only places I know where this does NOT occur by regulation are France and the US). Thus pink/orange may be the most difficult to detect in a patient’s mouth. Also, rather than a peel-pack, an applicator or inserter might be more practical, especially the custodial setting where large numbers of patients need to be given doses in a short space of time. A bright and contrasting colour would seem more sensible … so more effective consultation before introduction might have served the manufacturer and consumers better. This may also explain the fact that the company does not market a formulation smaller than 2mg. Many patients on Subutex are taking reducing (or sometimes increasing) increments of 0.4mg. In my experience most patients who successfully withdraw from the drug nearly always do so from such doses which are well under 2mg daily. It is a mystery to me why the company do not make smaller sized buprenorphine SL tablets available more widely. A sceptical reader might think that the company is more interested in patients remaining on treatment indefinitely!

Apart from reports of diversion (which Dr Strain said “where there’s a will there’s a way” or words to that effect), another part of the development rationale included worrying reports of children and even babies involved in Suboxone toxicity incidents in American emergency rooms. While Dr Strain initially raised this issue, when he was asked for details by an audience member at the end he said that he did not know any more about such events. I note that he writes in his recently published article (page 1) “unintentional exposure to B tablets in children under the age of 6 years has increased from 53 reported exposures in 2004 to 907 in 2008; from 2000 to 2008 there were 1,786 child-hood exposures to B”. This would seem to have answered the delegate’s enquiry to a tee.

Strain claimed that the use of the new “films” would be likely to reduce such occurrences … and one can only hope that he is right. Apparently Suboxone is sold as loose tablets in a bottle in America whereas elsewhere it is supplied in sealed blister packs. Further, the colour and flavour of Suboxone in America could make them much more interesting to young children than Subutex without the orange colouring and citrus flavouring. The pure formulation is indeed disgusting and children who tasted it would be most likely to quickly spit it out. Some Australian observers may think that we are being sold an American solution to an American problem.

We were told that there were about 300,000 taking buprenorphine in America on any one day. The total taking methadone maintenance in America was probably about 200,000 - and by law these were all restricted to registered clinics giving ‘comprehensive treatment’ under close supervision.

In answer to another question Dr Strain said that officially the next step in someone who was doing well on 2mg reductions was to go to second daily. Although second daily dosing can work well for maintenance patients, since reducing-dose patients are usually in withdrawals by the end of 24 hours the prospect of second daily dosing is just inappropriate when there is an option of reduction to 1.6mg. Unofficially, however, he said that the logical thing to do was to cut the tablet or patch in half. He said that Reckitts had said that they could not guarantee that the drug was evenly distributed amongst the dry tablet or the patch … yet Dr Strain said that this was not really tenable when the company seemed happy that the rectangle, cut from a large sheet of spray-dried film, was the same strength as the same sized rectangle next to it. This is another inconsistency of the presentation where the obvious answer was to use 0.4mg tablets which are commonly available in Australia at least.

Dr Strain’s conflict statement was given and I presume is the same as in his recent publication: “Dr Strain is a consultant to and paid member of the Scientific Advisory Board of Reckitt Benckiser Pharmaceuticals. The terms of this arrangement are being managed by the Johns Hopkins University in accordance with its conflict of interest policies.”

Refs: Robinson GM, Dukes PD, Robinson BJ, Cooke RR, Mahoney GN. The misuse of buprenorphine and a buprenorphine-naloxone combination in Wellington, New Zealand. Drug Alcohol Dependence (1993) 33;1:81-6

Bell J, Byron G, Gibson A, Morris A. A pilot study of buprenorphine-naloxone combination tablet (Suboxone®) in treatment of opioid dependence. Drug Alcohol Rev 2004 23;3:311-318

* Stop press report sent from NDRI: “Eleven charged in "Operation Postage Stamp;" Drugs smuggled into Carbon County Prison under stamps”. http://www.attorneygeneral.gov/press.aspx?id=6035

Comments by Andrew Byrne .. Part II John Mendelson on prescription drug abuse summary.