05/21/2012    Craig Herman, DPM

Lamisil, Tamoxifen Drug-to-Drug Interaction

I learned something new today that I think all
podiatrists should know. About 6 weeks ago, I
started a patient on Lamisil. Our electronic
record system (E-Clinical Works) checks for any
interactions between medications and no warnings
were issued. The patient came back today for her
6 week visit, at which time I planned on drawing
blood for hepatic function and a CBC. The
patient proceeded to tell me that her oncologist
told her to stop taking the Lamisil immediately
because it would decrease the effect of
Tamoxifen by interfering with how the body
activates Tamoxifen.

I found this very disturbing and potentially
very dangerous. We had always learned about the
effects of inhibiting CYP450. It had been
drilled into our heads about the potential drug
to drug interactions with Warfarin and SSRI's.
There is nothing in the package insert
specifically identifying Tamoxifen itself as a
problem. However, after doing some research, I
found out that Lamisil can also inhibit CYP2D6,
necessary for Tamoxifen. As soon as I Googled
the two drugs, I found a number of articles
stating this.

Next, I called four colleagues who are very
intelligent, have been practicing for over 10
years, prescribe Lamisil often, and whose
opinion I really trust. Not one of them has ever
heard of this drug to drug interaction. My
question to other podiatrists out there is, have
you ever herd of this interaction? If yes, why
do so many other respected podiatrists not know
about it and either way how do we get the word
out? It is not a potential life-altering and
threatening complication. If the effects of
Tamoxifen are reduced, the breast cancer can
recur. I would appreciate any input/knowledge
that other podiatrists have about this drug to
drug interaction.

Craig Herman, DPM, NY, NY, foothealer@aol.com

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05/23/2012    Charles Morelli, DPM

Lamisil, Tamoxifen Drug-to-Drug Interaction (Craig Herman, DPM)

This topic is a perfect one to segue into one
closely related and that is "Anti Rejection Drug-
to-food" interaction. Having recently received a
kidney transplant, I am acutely aware of these
hazards and as podiatrists, we all need to be
aware of them.

Being that we treat thousands of diabetics each
and every year, I can guarantee you that a
substantial number of them have had, or are in
need of a kidney transplant and if that is the
case, they are undoubtedly taking meds that need
to be taken not only at a specific time
interval, but also not in the presence of any
foods that can inhibit the P450 enzyme.

For kidney patients, grapefruit juice and
pomegranates are at the top of this list. Drugs
that use the same pathway and interact with
grapefruit juice and pomegranates target some of
the most common health problems we see every day
and the list consists of more than 50
medications, including drugs used to treat high
cholesterol, depression, high blood pressure,
cancer, depression, pain, impotence, and
allergies.

Transplant patients should not eat ANY food that
has not been washed thoroughly or has the
potential for carrying bacteria (raw meats and
sushi come to mind, including rare hamburger).
Avoid public salad bars as well, since you never
know whose hands have touched what you are about
to eat, nor do you know how long its been
sitting under the hot lights. In short, use
common sense.

Some meds should not be taken with milk.
Tetracycline will bind with the calcium in milk
and be rendered useless. This is "usually"
stated on the side of the medication. For
someone taking digoxin, some forms of licorice
may increase the risk for toxicity and will
reduce the effects of blood pressure medications
or diuretics.

Coumadin can be affected by foods which enhance
their effect and may cause excessive bleeding.
As we know, it inhibits the conversion of
vitamin K into its active form and foods high in
Vit K should be consumed carefully. Spinach,
broccoli, asparagus, cabbage, green beans,
lettuce and avocado come to mind.

Charles Morelli, DPM, Mamaroneck, NY,
podiodoc@gmail.com