High-Dose Methadone Boosts Cardiovascular Risk

[Jabberwocky]

May 24, 2011 (Austin, Texas) — Patients taking high doses of methadone have more cardiovascular risk, warn researchers.

"There is a dose-dependent effect on QTc interval in patients taking more than 120 mg per day," presenter Ricardo Cruciani, MD, from Beth Israel Medical Center in New York City, said here at the American Pain Society 30th Annual Scientific Meeting.

Investigators grouped chronic pain patients according to methadone dose and found the highest-dose group showed significantly more QTc prolongation. Lower doses ranged from 10 to 120 mg.

Dr. Cruciani's team considered a QT corrected for heart rate prolongation of more than 500 milliseconds as a definite risk for the potentially fatal arrhythmia torsades de pointes. Men with prolongations of more than 430 and 450 and women with increases of 450 and 470 were considered at risk.

Another national review of unintentional overdose deaths involving opioids came to a similar disturbing conclusion — a disproportionate number of poisonings are related to methadone.

In this new study, Dr. Cruciani's team focused on chronic pain patients and especially those older than 50 years, considered at higher cardiovascular risk. Investigators looked at 39 patients taking methadone and wanted to compare the effectiveness of a single electrocardiogram vs a 24-hour Holter monitor in detecting abnormal QT.

Torsades de Pointes

They found a single electrocardiogram detected fewer patients with QTc interval prolongations compared with a 24-hour Holter monitor (15 vs 20). However, the 2 approaches detected the same number of patients at risk for torsades de pointes.

Of note, Holter monitoring detected twice as many patients with QTc prolongations at noon compared with electrocardiogram. "This suggests that a single test might not be sufficient in identifying patients at risk," Dr. Cruciani said.

Despite the growing concerns over cardiac toxicity, many investigators suggest methadone deaths are a multipronged problem.

Dr. Webster's team studied malpractice cases in the United States, searched the literature, and reviewed other local and federal sources of information and found many reasons for the rising death toll.

"There's not one thing that caused this," Dr. Webster said when first presenting the results of his study. "There are multiple things that all add up."

A chief reason, his team suggests, is that conversion tables — used by physicians to transition patients from one opioid to another — recommend too much methadone for most patients. For example, Dr. Webster pointed out, through 2006, the US Food and Drug Administration recommended a starting dose of 80 mg per day. That recommendation has since been changed to 30 mg a day.

source : http://www.medscape.com/viewarticle/743289?sssdmh=dm1.690459&src=nldne

 

[BlueberryfishY]

Well Well leftwing... i saw that ban coming, sorry about your luck there bud but something had to be done.

 

[elviswearsnikes]

Many drugs can prolong the QT interval such as SSRIs, electrolyte imbalances and congenital disorders such as "Long QT Syndrome". The risk increases if someone has more than one contributing factor to prolonged QT interval... Such as concurrent use of an SSRI and a high dose of Methadone.

For example, lets say someone is on a high dose of methadone, that's also on an SSRI, who has a prolonged QT interval, who then decides to take a big puff on a crack pipe is unfortunately a recipe for a life-threatening cardiac arrhythmia such as TDP or VT/VF.

A routine ECG/EKG is normally requested here in the UK before an individual is started on Methadone and it is recommended to be repeated with dose increases above 100mg per day. The increase in QT interval is generally dose dependent therefore is likely to become more prolonged as the dose increases. As stated in the previous post, a QTc of above 500 milliseconds is a definite risk for a potentially fatal cardiac rhythm.

Before I started on methadone I was on Citalopram 40mg which I have subsequently reduced and stopped taking due to the risk of a prolonged QT. I had a baseline ECG which was normal and Mirtazapine was recommended instead as having less effect on cardiac electrophysiology.

 

['medicine cabinet']

I have this...my Dr wanted to give .e an EKG and found my qt was lengthend so I had to dropy .methadone. 10mgs later and my qt shortened. But I'm also on rx benzos and be said the combo can have something to do with it. I read as much as I could on it and the shit is serious....everyone out there on rx benzos and methadone, get a physical if you can and get an EKG.

 

[elviswearsnikes]

As previously posted, concomitant use of more than one drug that lengthens the QT interval is a potentially modifiable risk factor.

In other words, an individual who is one Methadone plus one other drug that lengthens the QT interval is potentially at risk.

Here is a list of some commonly encountered drugs that lengthen the QT interval:

Antimicrobials -
Erythromycin
Clarithromycin
Moxifloxacin
Fluconazole
Ketoconazole

Antipsychotics -
Risperidone
Fluphenazine
Haloperidol
Chlorpromazine
Quetiapine
Clozapine

Antidepressants -
Citalopram/ escitalopram
Amitriptyline
Clomipramine
Dosulepin
Doxepin
Imipramine
Lofepramine

Antiemetics -
Domperidone
Droperidol
Ondansetron

Other drugs include methadone, anti arrhythmics, protein kinase inhibitors, some antimalarials and some antiretrovirals.

If your on methadone, particularly on a high dose, plus one if the medications listed above, it may be wise to highlight this to your physician and ask about the risk of prolonged QT. This can also be identified on a routine ECG/EKG.

It's an important issue particularly as communication between a methadone clinic and general practitioner can be poor.

 

[sasha214]

Wow I never heard of this before. I take methadone and an snri but it's not listed there, but luckily I have puffed my crack pipe less and less over the years, almost none since being on my high dose, guess that's a lucky thing for me.

 

[ro4eva]

Prolonged QT intervals is a well-known risk among patients who are prescribed high maintenance dosages of Methadone daily. 120mg is widely established as the dose which the risk goes up significantly, and each additional 100mg on top of that results in a 2-fold increase in risk. At least, that's precisely what I've been told repeatedly by my MMT physician and also his colleague at one point who is another of three doctors working in the clinic I go to.

I was taking 260mg daily for a couple of years - thank goodness that my heart didn't give out on me because man did I experience some uncomfortable skipped beats at times (once every 24 hours I'd say).

Either way, what my above fellow BLers stated is correct AFAIK: There are quite a number of Rx drugs which are known to cause prolonged QT intervals & intra-ventricular conduction delays.

 

[cj]

As others have stated this is a known problem. I was warned when I went above 130mgs that I was putting myself at a small risk.