Consider half life during drug detoxification

A young man on my sobriety-based detox program (only after showing positive for opiates) admitted to heroin-usage, but hedged the matter saying it was “5 days ago.” His implicit presumption was that an isolated episode, days ago — compared to continuous, more recent, heroin-usage — would lessen the likelihood of his getting kicked off the program.

Is his story of “no heroin [ingestion] in the last five days,” likely, the whole truth? The half-life of heroin, itself, is only a few minutes; however, it metabolizes directly into similarly narcotic morphine, whose half-life is a matter of a few hours.

Do patients understand the concept of “half-life”? I explained (in a simpler fashion than the terms imply) the inverse exponential nature of the decay curve, i.e. that if morphine’s half-life is (to be very generous with him) six hours, then the “quarter life” is 12 hours; only 1/8 remains after 18 hours, and only 1/16 after one full day. After five full days, there would be 1/16*1/16*1/16*1/16*1/16, or around one one-millionth (!) of the original heroin-equivalent left, way beyond the sensitivity of qualitative drug-testing. In this young healthy man, morphine’s half-life more likely is only three hours, thus after five days, only one millionth of that one millionth, i.e. 1/1000000000000 remains.

Consider half life during drug detoxification
Most of my narcotic addicts have adequate and pragmatic math skills, in so far as knowing how to get enough money to feed a drug habit, but explaining a decay curve might be fruitless. I tried flipping the concept around and that seemed more understandable: asking how often, when fully addicted, he would have to take heroin. “Four or five times per day” was the answer. “Why four or five times per day?” I asked. “Because after a few hours, withdrawal-symptoms kick in.”

“Well, there’s your half-life! If heroin lasted four days and could be hanging around as morphine days later, you wouldn’t need to be taking it every few hours, you would take every few days”, I responded. And the point was made.

The same goes for marijuana, THC, albeit on a slower decay curve basis. My addicts (in a self-serving manner) always tell me that they “know” that marijuana hangs around for a month and will show positive for a month. They have that information on word-of-mouth. Certainly, on the outside, with high body fat content and high marijuana-usage level, marijuana (with a half-life of approximately 30 hours) will stay around longer; however, in actuality ~80% of my patients have it out of their system, according to qualitative testing, within about 5-7 days of beginning our sobriety program. Closer scrutiny and questioning almost always reveals that those with persistent positive testing of marijuana have had a few “lapses” using marijuana in the interim.

These are important points to emphasize during a detoxification, to stay on top of some of the ready-made excuses that narcotic addicts are very used to bringing up to avoid and evade closer scrutiny and full sobriety; often obtaining replacement-narcotic while indulging, still, in the “drug-life.” If a treatment professional is going to indulge these excuses, do so with eyes wide open, but invite even more testing of boundaries.

Randall S. Bock is a primary care physician who blogs at Withdraw to Freedom.

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