Wednesday, May 16, 2007

Deceiving patients; Methylnaltrexone

**I just republished this post because for some reason it wouldn't allow readers to comment. Email me directly if that is still the case. --Drew**

Happy belated Nurses’ Week for all of the nurses who follow the blog and those who love - or at least professionally admire - them. I am traveling through next week and this may be my last post until the last week of May. And yes, the fonts on this post are a little off - I can't figure out how to fix it.

1)
The most recent BMJ has an analysis about whether it’s ever moral for physicians to lie to patients. It actually, and without irony I think, presents a flowchart-type de
cision aide to help physicians make this decision. To the credit of the author the flowchart makes it highly unlikely that someone would conclude that it is permissible – the example below is the rather extreme circumstance in which the author concludes that it’s ok to lie.

“A patient with a ruptured aortic aneurysm is rushed to the operating theatre. The anaesthetist knows the patient's chances of survival are poor. Just as preoxygenation is about to begin, the distressed patient asks "I am going to be all right, aren't I, doctor?" Can the unhopeful anaesthetist justifiably deceive the patient?”

While the flip side to the author’s argument that is that it is almost never permissible to deceive a patient one wonders if the casual reader will conclude this. We are all afraid of ‘harming
’ patients by disclosing the truth, and some don’t need much of an excuse to be let off the hook.

(The same issue presents the results of a trial of a counseling program to prevent complicated grief after suicide. It didn’t seem to work.)

2)

Annals of Pharmacotherapy has a review on methylnaltrexone for opioid side effects. Methylnaltrexone, for those of you who haven't heard of it, is a peripherally acting opioid antagonist (it blocks the mu-opioid receptor peripherally but does not cross the blood brain barrier so has no effect on opioids central effects - analgesia, sedation, etc.). It is being commercially developed in the US and may be available relatively soon (this article was sponsored by the drug company developing it). It's given IV or subcutaneously. The article reviews its pharmacology and the evidence to date attesting its efficacy for opioid-induced constipation (seems to work). One particularly interesting effect of methylnaltrexone they mentioned is that it may be effective for opioid induced nausea: I had always thought of this as a central effect but they point out that since the chemoreceptor trigger zone is partially outside the blood brain barrier methylnaltrexone may be an effective anti-nausea agent. They go on to talk about how morphine is emetogenic in the CTZ but anti-emetogenic elsewhere in the CNS so if you give morphine + methylnaltrexone you get all the nausea relief and none of the nausea induction. Interesting physiology and sounds nice; seems to work in dogs apparently; I wouldn't hold my breath about this in humans though.

Now all we need is one for opioid-induced sedation and dysphoria....
There's no mention of how much methylnaltrexone is going to cost, assuming it is approved.

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