LONG-ACTING OPIATE MEDICATIONS-METHADONE and SUBUXONE

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There are only two long-acting opiate medications: methadone and buprenorphine.  Buprenorphine is the active ingredient in Suboxone and Subutex,  These are medications that are metabolized slowly.  The time it akes to metabolized half the methadone in the body is almost a day.  The time to metabolize half the buprenorphine is 36 hours.

Methadone has long been associated with heroin use because it has been used to stabilize opiate-dependent patients.  In fact, buprenorphine has also been approved for this indication and will, unfortunately, also become associated with drug abuse.  This has led, or will lead, to the stigmatization of use of these medications.

However, they are great pain medications.  Methadone was used as a pain medication for 20-30 years prior to its’ being adopted by the addiction medicine field.  In fact, recent reports in the media have revealed that President Kennedy was using this medication for a chronically bad back (It was in the mid to late sixties that methadone came to be used for addiction). 

The main benefit of methadone is that there is dip in pain relief during the day. It is quite inexpensive and easily represents the cheapest way of treating pain.  Even though, the half-life of methadone is quite long, clinical experience has shown that the pain relief only lasts about 6-8 hours after taking the medication. There is no explanation for this.  Therefore it is usualy dosed 3-4 times daily.
 
Unfortunately, many persons with chronic pain have been referred to methadone maintenance treatment programs for pain management.  These programs are designed for addiction treatment and are heavily regulated. They are forced to give the medication once daily to a majority of their patients.  Many patients with pain will tell you that their pain returns in the afternoon and can worsen as the day and evening progress. 

Over the last couple of years, scientists have learned about another major benefit of methadone.  It has to do with the isomeric variant.  When a drug is created in a lab, both the drug and a mirror image (isomer) of the drug is made.  It had been thought that that this isomer was inactive.  In fact, the isomer can block activity at the NMDA glutamine receptor.  This receptor is responsible for aiding in the transmission of pain.  It may also be a major cause in the development of neuropathic pain.  By blocking this receptor, there is a reduction of pain.  In addition to pain relief, blocking the receptor has been linked to reducing the development of tolerance to the methadone.  For this reason, pain relief with methadone may be longer lasting than with other opiates.

Methadone will accumulate in the body.  This has several consequences.  If we try to titrate up the dosage too quickly, someone can overdose.  Also, the first dose may not lead to overdose whereas the a second or third dose might.  This is the basis of a lot of malpractice suits.

Another consequence is that it is more potent at higher doses.  !0 mgs of methadone is equivalent to 20mgs of oxycodone at a low dos.  At a higher dose, it is equvalent to 50 or 60 mgs.  This is one reason it may be harder to wean from than other opiates. 

It may be more likely to cause nausea and fatigue.  It will cause more sexual hormonal disturbances than most opiates.  Woman lose their periods and men have their testosterone levels lowered.  There is no truth to a common misconception that it gets into the bones; although, osteoporosis can be more likely secondary to the sex hormone inbalances.  

Methadone, like all opiate drugs, is a safe medication.  Recent experience, however, have caused doctor to be extra cautious.  There has been evidence that it affects the electrical rhythm of the heart which may result in a life threatening process.  There is also a greater chance of respiratory  depression even when used as directed.  Despite the severity of these problems, their incidence is quite low and the drug can be used safely in many.  
 

Buprenorphine has been available for over 15 years.  It was originally approved as an injection.  It now comes in a pill form (or a dissolvable film) that is place under the tongue.  The medicine has to be absorbed from underneath the tongue.  Any medication that is swallowed will be metabolized by the liver and lost. 

It is more potent than morphine.  This makes doctors nervous because they really do not understand what potency means.  High potency does not mean a drug is stronger.  It means that a similar effect is achieved with a lower number of milligrams.  0.3 mgs is equivalent to 10 mgs of morphine.  Therefore it is 30 times more potent as a pain reliever.  However, with increasing dosages, the effect of morphine increases to a greater degree than buprenorphine.  Also, buprenorphine causes minimal intoxication no matter what the dose.  So, even though it is more potent, it is less powerful and less intoxicating.  In fact, it is the best drug in terms of tolerability.

It is not as powerful as many other opiates; however, I estimate that at least 2/3rds of patients will get adequate relief.  I estimate that the maximum effectiveness is equivalent to about 180-240 mgs of morphine.  If someone is already on large amounts of pain medication, switching to buprenorphine can be associated with withdrawal.

Since it is not as intoxicating and has a plateau in its’ effectiveness, it is not as addictive as other opiates.  It also acts as a blocker for other opiates.  I tend to use this medication either in persons who have been unreliable in the medication use or in persons who could not tolerate other drugs. 

 

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