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The Painkiller That Saves Money But Costs Lives
Hugh Pickens writes "Over 2,000 patients have died since 2003 in Washington State alone by accidentally overdosing on a commonly prescribed narcotic painkiller that costs less than a dollar a dose and the deaths are clustered predominately in places with lower incomes because Washington state has steered people with state-subsidized health care — Medicaid patients, injured workers and state employees — to methadone because the drug is cheap. Methadone belongs to a class of narcotic painkillers, called opioids, that includes OxyContin, fentanyl and morphine. Within that group, methadone accounts for less than 10 percent of the drugs prescribed — but more than half of the deaths and although Methadone works wonders for some patients, relieving chronic pain from throbbing backs to inflamed joints, the drug's unique properties make it unforgiving and sometimes lethal. 'Most painkillers, such as OxyContin, dissipate from the body within hours. Methadone can linger for days, pooling to a toxic reservoir that depresses the respiratory system,' write Michael J. Berens and Ken Armstrong. 'With little warning, patients fall asleep and don't wake up. Doctors call it the silent death.'"
Overdose isn't when you take more then prescribed, it's when you take more then what your body can handle.
As such most overdoses are accidental.
It's prescribed as a painkiller more often than as a treatment. I'm a pharmacist and I go through methadone like mad and not on the prescriptions I fill is for addicition. I spoke to a pain doctor once who told me it was a cheaper alternative to OxyContin, which can run $600/month without insurance. Methadone runs about $30 a month without.
Some patients with insurance won't take OxyContin because their copay is high.
Methadone's pharmacokinetics give it a long half-life, and therefore a long duration of action. This is an asset in managing chronic pain from cancer and some other diseases. Methadone has much less tendency to lose its analgesic effect through habituation. Morphine, for example, while an effective pain reliever due to its action on the mu-opioid receptor, has a metabolite that acutally upregulates perception of pain due to action on the NMDA system. This latter effect probably accounts for most of the often-observed dose escalation needed to maintain effective analgesia in patients treated with morphine. The primary danger of methadone is that physicians who are unaware of its comparitively slow pharmacokinetics overdose their patients because they escalate the dose too fast. It is critical to make changes (either increase or decrease) in methadone dosage *slowly* - when that is done, the drug can provide chronic pain relief with a much better combination of safety and long-term effectiveness than many of the other opiates. As always, ignorance seems to be the most deadly disease.
In terms of pharmacodynamics, methadone is a garden variety opiate. It has two major distinctions: it has good oral bioavailability, and it is long-acting (i.e. it has slow pharmacokinetics). These are major advantages for people with chronic pain. Morphine has poor oral activity, and also wears off fast. This makes it good for intravenous infusion in a hospital setting, but terrible for patients with severe chronic pain. One aspect of opiate analgesia is that once the pain "breaks through," it is hard to knock it down again. Opiates work best for pain relief if blood levels are kept reasonably constant. So with a short acting opiate, patients have to be constantly popping pills. A long-acting opiate makes it possible for a patient with chronic pain to live something approaching a normal life.
Respiratory depression by opiates tracks very well with pain relief, so it is not plausible that the respiratory depression would greatly outlast the pain relief, as claimed in the article. Moreover, we have a huge amount of experience with methadone, because it is widely used for opiate maintenance in opiate addicts. Opiate addicts take methadone under supervision, so they can't escalate their doses. So we know that when methadone is taken as prescribed on a regular basis, it is safe and effective, and toxic levels do not build up in the body.
I think that this is a problem of poor patient and physician education and poor choices by physicians in prescribing a long-acting drug to patients who don't really understand what that means. The average patient has no experience with long-acting pain relievers, because all of the commonly used medications such as hydrocodone are short-acting. The pain relief of a long-acting opiate lasts a long time, but it is also slow in onset. This is an unavoidable aspect of the pharmacokinetics of long-acting drugs. That means that you can't wait until you start hurting, then take a methadone pill and expect the pain to go away in under an hour, as with short-acting drugs. It will take days for the pain relief from methadone to build up to its full level. A patient who doesn't understand this is likely to think, "It isn't working," and take more than the prescribed dose--and then when it does build up, they end up in respiratory depression.
There is no way to have a long acting opiate pain killer drug that does not carry the same risk as methadone. The same hazards apply to oxycontin (which is a time-release formulation of a short-acting opiate, oxycodone).
So the patient needs to be told in no uncertain terms, "This isn't a drug where you can wait until you start hurting and then take a pill. It won't work, and it is dangerous to take it that way. You must take it on schedule, every day. You can't take extra even if you are hurting. If you miss a pill, don't take extra to make up. If you take more than the prescribed dose, or take it more often than prescribed, you may DIE." And the doctor needs to be absolutely certain that the patient understands this and is capable of complying. If not (or if there is not a reliable care-giver capable of controlling dosing), then the patient should be prescribed a short-acting narcotic (although this carries its own, different risks).