Question-toxic levels of alprazolam, nordiazepine, and amitriptyline

[whopper]

Anyone know of any online resources where I can check where these medications become toxic?

I'm a psychiatrist, and this is usually outside my field. I need some reference ranges, and I can't find any online.

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[deleted109597]

Goldfrank's? Your facility should have a micromedex/toxindex somewhere online as well.

 

[njac]

even so, there aren't recognized "therapeutic ranges" or "toxic levels" for these medications. It tends to be symptomatic - these are often send out labs and will take days to get back anyway, too late to be of much good when taking care of the patient.

I just busted out my Goldfrank's and there aren't reference ranges for any of those medications.

For TCAs it says "Serum concentrations usually do not correlate with acute clinical toxicity for these reasons." [large volume of distribution, prolonged absorption phase, long distribution t-1/2, pH-dependent protein binding, intrapatient variability of terminal elimination t-1/2, and development of tolerance among people chronically taking these medications].

It does go on to say that levels >1000ng/mL usually are observed in pts with significant clinical toxicity, and that therapeutic TCA concentrations are generally 50-300 ng/mL. But no specifics for each TCA, and those include active metabolites as well.

There is no information on levels of benzodiazepenes.

I know we've gotten levels on various TCAs on O/Ds in the past - but I don't think there's much we can do with the level other than go "oh hey, his amitriptyline level was 600 ng/mL" - sort of like when they order Keppra levels. Sure we can get it - but it doesn't mean anything.

 

[whopper]

Thanks for all the replies.

I'm a forensic psychiatry fellow, and I was working on a psychological autopsy. These are reports done to see if someone's death was suicidal or not (e.g. accidental, murder), that are outside the scope of pathology. E.g. if someone overdosed on heroine, was it suicide or not? After the coroner, the next person to evaluate is a psychologist or psychiatrist with forensic training. The coroner's report had levels of the meds I mentioned.

I currently spend most of my time in a forensic psychiatric hospital, not a medical hospital, and for that reason, I didn't have a Goldfrank's available to me.

Last time I had to check one out, I had a patient who chronically ingested rat poison.

I called a number of places including poison control. They referred me to the federal aviation administration website that gave reference numbers for some, but not all of the meds I requested. I guess they need them to see if pilots are inebriated?

 

[dlung]

Thanks for all the replies.

I'm a forensic psychiatry fellow, and I was working on a psychological autopsy. These are reports done to see if someone's death was suicidal or not (e.g. accidental, murder), that are outside the scope of pathology. E.g. if someone overdosed on heroine, was it suicide or not? After the coroner, the next person to evaluate is a psychologist or psychiatrist with forensic training. The coroner's report had levels of the meds I mentioned.

I currently spend most of my time in a forensic psychiatric hospital, not a medical hospital, and for that reason, I didn't have a Goldfrank's available to me.

Last time I had to check one out, I had a patient who chronically ingested rat poison.

I called a number of places including poison control. They referred me to the federal aviation administration website that gave reference numbers for some, but not all of the meds I requested. I guess they need them to see if pilots are inebriated?

Just be careful interpreting forensic drug levels. You need to separate your interpretations of Pre- vs Peri- vs Post-mortum drug levels. Makes sense. Peri-death, the serum rapidly becomes profoundly acidotic --> redistribution of drugs.

 

[njac]

On my Tox rotation as a student we went to the ME every week for the difficult case conference. The toxicologist had a book that referenced post-mortem pharmacokinetics and had levels and whatnot. Of course I don't remember what the book was, but it's worth trying to talk to the toxicologist at your poison center as they may know.

 

[BADMD]

Anyone know of any online resources where I can check where these medications become toxic?

I'm a psychiatrist, and this is usually outside my field. I need some reference ranges, and I can't find any online.

Basalt is the most widely used reference for this.

Keep in mind that there are a lot of "ifs, ands and buts" associated with associating levels with toxicity. Things aren't clean cut. Habituation, source for the sample, time since drawing, comorbidities, other drugs, whether the patient was alive, about to die, dead or very dead and multiple other factors can alter the correct interpretation of a level in regards to toxicity.

The clinical senario is critical to a correct interpretation.