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	Having watched the Sudafed drag on for a while, I thought I
would add some comments which I hope are more light and less heat...I
am not a MD nor do I have an professional training in DCI medicine, so
what follows is speculation.

        I, too, checked with DAN, who as others have noted said "yes
some involvement, but statistics are low".  I then called some friends
in the research diving community.  Their reply was "Sudafed=DCI".
Essentially, in the research diving groups locally it is STRONGLY
discouraged and they know of many incidents and complications.

        As a drug designer/modeler, I want to point out that the
effects of many antihistamines are highly highly variable from one
person to the next and without knowing the molecular basis for the
Sudafed problems, I think that there isn't much that one can
conclusively say about whether or not it is likely to happen to any
one person.  I think that we can say that it does happen and you can
reduce your chances for DCI if you are not taking it.(Blocks are
another story.)  Personally, I have my own guesses and I bet that
almost any decongestent, including caffeine has a measurable effect
due to the constriction of the capillaries and the resultant decrease
in area for gas exchange, but I do NOT KNOW THAT THIS IS THE CASE.
GUESS ONLY!

        As an aside, Seldane and its related compound Hismanal are
special antihistamines- they do not cross the blood/brain barrier at
normal pressure.  This means that virtually all of the neurological
side effects (jitters/vertigo/ drowsiness) are absent.  I would ASSUME
that this is also true under pressure but I do NOT KNOW that it is the
case.  Since these compounds do not contain drugs like adrenaline and
caffeine, the blood vessels are not constricted and (in my private
guessing) are probably not as likely to interfere with outgassing, but
this is only a guess based on how I personally think the process
works.  Again, without knowing the molecular causes, it is
hard/impossible to extrapolate.

	I hope this helps,

		Peter

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