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Re: [IP] Need Your Opinions...Please!

> Date: Wed, 5 May 1999 08:38:40 -0800
> From: "Michael" <email @ redacted>
> Subject: Re: Re: [IP] Need Your Opinions...Please!
> There is specific scientific information that refutes the assertion
> that Humalog degrades in plastic. Humalog is perfectly stable in
> plastic syringes and tubing. See:
> http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?uid=9203437&form
> =6 &db=m&Dopt=b
> or the first link under HUMALOG on the LINKS page of the
> insulin-pumpers web site.
> Michael,
> Good citation.  According to the study, quoting now;  "CONCLUSIONS:
> We conclude that insulin lispro is suitable for prolonged infusion
> in these two medical devices when syringes and catheters are
> replaced at 48-h intervals."
> Many of us pumpers are changing cartridges at longer intervals.  The
> writers on the insulin-pumpers list have cited problems of
> degradation in their (plastic) cartridges after 8 days or more. 
> That study doesn't specifically address those problems.
> Anecdotally, at least one MM pumper has outlined his regimen as
> using cartridges only half (or 48 hours or so) full.  Do they do it
> because of the results of the aforementioned study or because they
> have experienced the degradation firsthand?
> Presumably the conductors of the study would have used plastic in
> both brands of pumps, so to reduce the number of variables.
> As a Disetronic pumper who has also used plastic, I would recommend
> using glass.
> Would anyone know why MM uses only plastic?
> Richard
> email @ redacted
> Michael
> > At 09:07 PM 5/4/1999  Richard Aleksander wrote:
> >  >Humalog degrades in air and in plastic.  MiniMed pumpers, using
> >  only plastic >cartridges,  have these problems more than Disetronic
> >  pumpers.  Disetronic >pumpers who use only glass cartridges will
> >  avoid potency problems by filling >all 3 glass cartridges at the
> >  same time, from the new bottle of Humalog.
> >

You must read more carefully. From the middle of the document:

"RESULTS: Insulin lispro retained full HPLC potency (delta < or =
4%) at 48 h, with no degradation of insulin lispro to des-amidoinsulin
forms (24 or 48 h)." 

Their conclusions are based on finding "no degradation". It is an 
obvious conclusion based on the findings. The study period was only 
48 hours so they can not make any statement about periods longer than 
that. We must draw our own conclusions from the findings and what 
ever other information we can dredge up.

Of more interest,
the document states that test was performed:

".....after 24- and 48-h pump cycles conducted at
37 degrees C "

If you check further with the Lilly (I quote a letter from them to 
me dated Jan 13, 1998), you will find that: (and I quote) "As an 
example, a vial of insulin stored at 86F(30C) will lose approximately 
1.7% of its potency over 30 days. In contrast, insulin stored in a 
refrigerator woll lose less than 0.1% of its potency over 30 days" 

In conversations with a representative of Lilly, she made it clear 
that elevated temperature will accelerate deterioriation in a highly 
non-linear fashion.

The expected deterioriation from temperature alone in the cited test 
should have been 0.06% for the 48 hour period. Probably not easily 
measureable given the "noise" in the test setup. My point is that 
any measureable insulin deterioration would have been almost entirely 
due to ambient temperature and based on a finding of "none" in the 
study done on plastics, it is a very reasonable conclusion to use 
plastic syringes, tubes, etc.... for a period equal to the life of 
the infusion site. Ancedotal evidence on this list suggests that 
periods of 4 to 7 days are not uncommon.

You may have personal ancedotal experience with some kind of problem 
with insulin deterioration, but you comments stated as "fact" only 
confuse people about things which most probably are not true based on 
the studies and evidence at hand..

We must be careful on the mail list not to use personal ancedotal 
experience as a statement of fact without careful "qualification". We 
are all aware of problems with apparent "site deterioration", 
"insulin impotency", and so on... but the reasons for these things 
are not well understood, even by scientests. We must endeavor to make 
sure others are not detered from using a safe effective insulin in 
commonly available syringes and infusion sets because of 

email @ redacted
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