Posts Tagged ‘phenergan and methadone’

News From the World of Addiction Medicine Research

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The latest issue of the Journal of Addiction Medicine, Vol. 7 (2) March/April 2013 had several interesting articles relating to opioid addiction and its treatment. Here’s my quick summary and thoughts on one of them, “Promethazine Misuse among Methadone Maintenance Patients and Community-Based Injection Drug Users,” by Brad Shapiro et al, pp. 96-1001.

This study attempted to get an idea of the prevalence of promethazine (better known under its brand name Phenergan) use in opioid addicts both in and out of treatment.

I was interested in this article because I’ve had methadone patients misuse promethazine. Most of these patients say that Phenergan gives them sedation with methadone, but most say it’s not a true euphoria, so I’m puzzled as to why they mix the two. Since promethazine can be sedating in many people, obviously I worry about overdose deaths when it’s mixed with methadone.

The authors of this study tested for promethazine in the patients enrolled in a county hospital methadone clinic in San Francisco. Twenty-six percent were positive for promethazine and only 15% had a prescription for this medication. Also, promethazine use was associated with benzodiazepine use.

The authors then recruited two hundred intravenous drug users, and discovered that only 139 were opioid addicts. Of those 139 addicts, seventeen percent reported promethazine use in the past month. However, of the addicts who had been on methadone in the past, twenty-four percent reported promethazine use in the past month.

What does this study tell us? The authors’ conclusion was that promethazine needs to be investigated further as a drug of abuse in opioid addicts.

Well, yeah.

My clinical experience gave me some thoughts about the study. For one thing, pregnant addicts were excluded. But in my experience, pregnant patients are the ones most likely to be prescribed Phenergan because of morning sickness during pregnancy. And this study doesn’t tell us much about the overdose risk when methadone and Phenergan are combined. Early in their article, they do provide some data: In Kentucky, over 14% of decedents from methadone toxicity overdose deaths also had promethazine present in their system. In Seattle, 2.5% of fatal overdoses had promethazine present.

Promethazine, along with many other medications, prolongs the QT interval just like methadone does. I haven’t seen any studies of methadone patients comparing QT intervals before and after promethazine, which may be helpful to further assess risk.