From: dyer@spdcc.com (Steve Dyer)
Newsgroups: sci.med
Subject: Re: questions about Cyclokapron
Date: 16 Aug 92 23:51:59 GMT
Article-I.D.: spdcc.1992Aug16.235159.16964
Organization: S.P. Dyer Computer Consulting, Cambridge MA

In article <1992Aug14.182631.4257@bcrka451.bnr.ca> seanna@bnr.ca (Seanna Watson) writes:
>My gyn. prescribed Cyclokapron to control very heavy menstrual bleeding.
>He said that the only adverse side-effect is the cost (>$1 per pill).
>I would like to know a little bit more about what it does and how it 
>works.  Also, since I take terfenadine (Seldane) which is OTC here, I
>was wondering if there were any potential interactions.  (And yes, I am
>going to ask my pharmacist.)  Thanks in advance.

Cyclokapron is the tradename for tranexamic acid, an anti-fibrinolytic
drug related to aminocaproic acid.  I'm not a gynecologist or even a
doctor, so take these comments with this in mind.

Its FDA-approved use is as an adjunctive drug to reduce bleeding after
dental surgery in hemophiliacs.  It does this by inhibiting the
activation of plasminogen, a circulating component of blood which can
be "activated" by a variety of proteins to form plasmin, a substance
which dissolves ("lyses") clots by enzymatically attacking fibrin, the
primary protein associated with clots.  The drug also reduces the
ability of plasmin to bind to fibrin.  You can compare this drug's
actions with a drug which works in precisely the opposite manner:
tPA (tissue plasminogen activator), which has become almost a household
name through its use during the early stages of heart attack to dissolve
the clots which cause the obstruction.

The drug has found some use in treating menorrhagia (that is, very
heavy menstrual bleeding) by reducing the amount of blood lost.  It's
administered at the onset of menstruation and for several days
thereafter.  The primary (rare) toxic effect noticed is a diminuition
of color perception; for that reason the drug is contraindicated in
people with impaired color vision (because such toxicity would be hard
to detect).  I don't really know what the standing of such therapy is
in the gynecological community and what its standing is compared to the
administration of NSAIDs or oral contraceptives.  Maybe someone like
Len Howard can offer his comments.

Now, here's just my own two cents: I would not be inclined to
cavalierly ingest any drug on a regular basis which systemically
affected the delicate balance of clot formation and breakdown
throughout the body, unless I were so ill that the risks of such
therapy were less than the disease I had.  Given that menorrhagia
(where other contributing factors have been ruled out) is a benign
(albeit annoying and bothersome) problem, I'd want to be sure that I
wasn't subjecting myself to unnecessary risk.  The impression I get is
that tranexamic acid has been rather safe on the whole, but there have
been reports of thrombotic episodes in isolated instances, including
women for whom it was administered for menorrhagia.  Part of its safety
record may simply reflect the fact that it isn't a very widely used
drug, and its wider use may uncover a truer incidence of adverse
reactions, especially in widely differing populations.  I'm not
trying to be alarmist here, just realistic.

As for drug interactions, there aren't any I know of (other than
obvious ones surrounding other drugs which have effects on clotting:
anti-coagulants, aspirin, etc.)  Which is not to say that there
won't be any with terfenadine.  Terfenadine's interactions with
erythromycin and ketaconazole were noted as adverse drug reactions
well after it was approved and in use.

-- 
Steve Dyer
dyer@ursa-major.spdcc.com aka {ima,harvard,rayssd,linus,m2c}!spdcc!dyer