methadone and subutex dose equivalents

[Pharmacologic]

I find it hard to believe no doctor anywhere has ever entertained the though of experimenting with opiates. I find it easier to believe that doctors, pharmacists other health care professionals exposed to such drugs in the work place could easily get into a compromising situation. I would even go so far as to suggest it could be an occupational hazard..

Unfortunately the world is not as black and white as you suggest Fleegle.

Anyway, I hope the references provided information to professionals assisting patients to make the transition the OP was talking about.

[johnep]

According to a list published in the PJ 13/12/2008
Methadone potency to morphine is 0.1 : 1.0, ie about 10%.
johnep

[bobbin]

According to a list published in the PJ 13/12/2008
Methadone potency to morphine is 0.1 : 1.0, ie about 10%.
johnep

Methadone is a very potent opioid......but it's potency is very variable. A single (isolated) 10mg dose of oral methadone may be quite similar in potency to oral morphine.............but on repeated dosing methadone may be up to 10 times more potent than oral morphine. This is especially relevent to patients who are receiving very high doses of morphine for analgesia. If a transfer to methadone is contemplated due to inadequate pain control despite high-dose morphine (eg. >600mg per 24 hours), approx. 1/10 of the dose of oral morphine may be appropriate initially, adjusted according to response under close supervision. Although difficult to use due to its unpredictable pharmacokinetics, methadone remains a useful treatment for some patients with severe chronic pain, particularly when other potent opioids have been tried but rapid dose escalation has been necessary..........and possibly in patients whose pain has a neuropathic element. Although methadone is used by some pain specialists and palliative care consultants in the UK, it is used for this purpose significantly more frequently in the US........where its very low cost in comparison to controlled-release morphine, OxyContin and Durogesic is highly relevent. In the absence of an NHS, the cost of drugs is very important. Many patients are simply unable to afford high doses of expensive products such as OxyContin.

With regard to the relative potency of methadone and Subutex.........it's not really possible to come up with a figure due to the fact that methadone is a full opioid agonist whereas buprenorphine is a partial agonist. Estimates of relative potency are only appropriate for drugs which have an identical mechanism of action.

Bobbin

[Tony Schofield]

For treating opiate dependence the maximum licensed dose of buprenorphine is 32mg. Above this dose there is no evidence of any added benefit. Methadone can be increased massively however. The biggest dose I have seen (and supervised!) was 500ml and I regularly prescribe some patients doses over 200ml. The most common doses of methadone are between 60 and 120ml but as there is a 100 fold variation on ability to metabolise methadone within the population there are big variations around those doses.

As buprenorphine is a partial agonist it can block the receptors without producing some of the effects of opiates eg euphoria, drowsiness etc. Consequently patients on buprenorphine note feeling clear headed, requiring less sleep and being alert which is not the case with methadone. Patients frequently express a preference for one drug or the other based on this experience.

Also as buprenorphine displaces opiates abruptly from receptors whilst not producing many of the effects (as stated above) of opiates it can precipitate withdrawal symptoms which is deeply distressing for the patient. Hence only initiating buprenorphine when the patient is in withdrawal already.

The drugs do not have directly equivelant doses. So whilst starting a patient on titration with 30ml of methadone mirrors starting a patient on 4-8mg of buprenorphine, they are safe starting points not equivelant doses. So 18mg of buprenorphine would be impossible to translate into an equivelant methadone dose.

Buprenorphine is the first line drug in France.

[Fleegle]

Bollocks


Jeff

Thank-you for the eloquence of your reply Jeff. I await your next post with indifference.

Fleegle.

[bobbin]

For treating opiate dependence the maximum licensed dose of buprenorphine is 32mg. Above this dose there is no evidence of any added benefit. Methadone can be increased massively however. The biggest dose I have seen (and supervised!) was 500ml and I regularly prescribe some patients doses over 200ml. The most common doses of methadone are between 60 and 120ml but as there is a 100 fold variation on ability to metabolise methadone within the population there are big variations around those doses.

As buprenorphine is a partial agonist it can block the receptors without producing some of the effects of opiates eg euphoria, drowsiness etc. Consequently patients on buprenorphine note feeling clear headed, requiring less sleep and being alert which is not the case with methadone. Patients frequently express a preference for one drug or the other based on this experience.

Also as buprenorphine displaces opiates abruptly from receptors whilst not producing many of the effects (as stated above) of opiates it can precipitate withdrawal symptoms which is deeply distressing for the patient. Hence only initiating buprenorphine when the patient is in withdrawal already.

The drugs do not have directly equivelant doses. So whilst starting a patient on titration with 30ml of methadone mirrors starting a patient on 4-8mg of buprenorphine, they are safe starting points not equivelant doses. So 18mg of buprenorphine would be impossible to translate into an equivelant methadone dose.

Buprenorphine is the first line drug in France.

How frequently do you do an ECG when prescribing very high doses? Have you seen many cases of QT-interval prolongation?

[Tony Schofield]

We are starting to ecg on doses over 100ml. I haven't personally encountered QT problems but some of my colleagues have.

[flukee]

i also am considering the transition from methadone to subutex. I am on a stable does of 20 mls of 1ml/1mg of oral methadone but am concerned by the precipitated withdrawals transfering to subutex can cause. about 7 or 8 years ago i was prescriped bupe for tooth ache by a GP who knew i was an active heroin addict. This put me into withdrawal and being less educated on treatements, medications ect at this time I could not understand why this happened. So undertsandably when i was offered subutex as a treatment i was far to scared to put myself through that again and took the "easy" option of methadone. That was my second biggest mistake, my first being starting heroin in the first place. I havent much else to say that hasnt been said about subutex although if this is being offered as a treatment or you are considering offering subutex as an alternative to methadone, do it. methadone is hard as hell to come off and enables relapse far to easily.
Also to the person who implied people in medicine do not take drugs. I have just spent a week in detox with 2 GPs with the same problem as mine. There but for the grace of god there go i comes to mind.

[Tony Schofield]

The only way to manage a transition from 20ml methadone to subutex is to do without the methadone for up to 72 hours and manage your withdrawal symptoms. Drugs like buscopan, quinine and paracetamol spring to mind but I have successfully use lofexidine (the patient was on a higher methadone dose of 60ml). You can then safely titrate the buprenorphine.

However, if you have done a withdrawal from 20ml, would you not fancy taking naltrexone to stop you relapsing? You will have done the hardest part!

[flukee]

Tony
Thank you for your reply. The detox was not completed as I reacted badly to lofexidine, severe burning and rash, also although I have hard detoxed from heroin before I have never experienced anything as horrendous as a methadone detox. My game plan was to start naltrexone on leaving 6 weeks of rehab. Unfortunately this wasn't to be. Although that is my ultimate goal once I have reached the end of my opiate treatment. I think along with adverse reaction to lofexidine my detox planners had not fully appreciated I had reduced from 3.5g of heroin and 60 mg of methadone a day to 25 mg of methadone in 6 weeks in order to meet their criteria. The detox included a cushion dose of mst but others in the community suffered no ill effects just disturbed sleep. My detox wasn't helped by the immediate stopping of 15mg of zopiclone by the detox centre which I had been on for 7 years.