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From: (Steven B. Harris )
Subject: Re: Penicillin V
Date: 15 Sep 1995

In <> (Peter Wroblewski) writes:

>Does anyone know what the V stands for in penecillin V.

   I think they just named early mold products by letters of the
alphabet, and penicillin G and penicillin V are the only ones of this
early set which we still use.  The pen G (more active against gram
negatives) is used for IV use, and the pen V, which is better orally
absorbed, in pills.  When you see "VK" that means the potassium salt (K
= kalium = potassium).

                                          Steve Harris, M.D.

From: (Steven B. Harris )
Subject: Re: Penicillin V
Date: 24 Sep 1995

In <443ltj$> (Chicago)
>Why do they use units for Penicillin Instead of milligrams?

   It's a holdover from the days when penicillin wasn't 100% purified
from the mother liquors of the mold cultures it was made in, and nobody
knew how many "units" (measured by ability to kill bacteria) a
milligram of absolutely pure penicillin had! In case you're wondering,
the answer is that a milligram contains about 1600 units.  The only
penicillin still given in units is penicillin G, and that only for
historical reasons (all the studies are done using these figures).
Every other penicillin drug and derivitive is now given in milligrams.
I suspect pen G will eventually give way and be used in milligrams
also, but meanwhile there has to be something arcane left to justify
what we pay specialists.  Where would be be if it was all easy?
Doctors would have to get honest jobs, like fixing cars.

                                                 Steve Harris, M.D.

From: Steve Harris <>
Subject: Re: Keflex pills: is it my imagination or do they smell?
Date: 8 May 2005 13:46:24 -0700
Message-ID: <>

"df" <> wrote:
> I notice that my bottle of Keflex 500mg capsules smells like rotten
> eggs.  The bottle was only filled last week.  Is this normal?

>>Apparently.  I remember smelling that when I was taking it.  I think
sulfur is part of whatever Keflex is made of. <<


Indeed. All the antibiotics in the penicillin and cephalosporin class
(of which Keflex/cephalexin is one) have the beta-lactam ring nucleus,
which contains a sulfur atom. Breakdown products and impurities, even
in new and well manufactured pills, lead to that sulfury smell. It's
especially apparent in tablets (ie Pen VK) and capsules (like your
Keflex), and not so bad in the film coated more-expensive members of
the class like Ceftin (though you can still detect it in cut pills). So
you'll smell a trace of sulfur in the drug itself, and if not, you'll
certainly smell it after it's passed through your gut.


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