******3 - fexofenadine

[ArchivalUser]

A 40-year-old man with a long history of medically
managed Crohn™s disease presents with
shortness of breath. He complains of repeated
incidents of bruising following minor trauma
and increasing weakness. Laboratory tests
show:

Hemoglobin: 5.5 g/dL
Hematocrit: 13%
WBC count: 2200/mm3
Platelet count: 39,000/mm3

A bone marrow biopsy showed replacement by fat cells.
A detailed history reveals that the patient had
an acute episode of gout 3 months ago and was
prescribed a medicine to prevent future attacks.
Adverse interactions of which two drugs
most likely caused this patient™s condition?

(A) Azathioprine and allopurinol
(B) Azathioprine and colchicine
© Infl iximab and colchicine
(D) Prednisone and allopurinol
(E) Prednisone and colchicine

[ArchivalUser]

C?

[ArchivalUser]

Try again

[ArchivalUser]

a??

[ArchivalUser]

aa????

[ArchivalUser]

(A) Azathioprine and allopurinol
Allopurinol may potentiate the pharmacologic effects of orally administered thiopurines. Severe bone marrow suppression and other toxicity have been associated with concomitant use of allopurinol and mercaptopurine (6-MP) or azathioprine

[ArchivalUser]

The correct answer is A.

Azathioprine is a
common treatment for Crohn™s disease; its
metabolite, 6-mercaptopurine, is normally inactivated
by xanthine oxidase. Allopurinol is a
xanthine oxidase inhibitor used to prevent repeat
gout attacks. When these two are used
concomitantly, allopurinol interferes with the
metabolism of azathioprine™s toxic metabolite,
which can lead to fatal hematologic disorders,
such as aplastic anemia, as in this case.
Answer B is incorrect. Colchicine can be used
to treat acute gout. It binds to tubulin and prevents
microtubule polymerization. It does not
interfere with azathioprine metabolism and is
not known to cause pancytopenia. Colchicine
can, however, cause cytopenia.
Answer C is incorrect. Infl iximab is an antitumor
necrosis factor-α monoclonal antibody
sometimes used to treat Crohn™s disease. It is
not known to interact with colchicine to cause
pancytopenia.
Answer D is incorrect. Prednisone is a corticosteroid
that can be used to manage Crohn™s
disease. It is not known to have fatally adverse
interactions such as pancytopenia when used
with allopurinol.
Answer E is incorrect. Although prednisone is a
treatment for Crohn™s disease and colchicine a
treatment for gout, the two can be safely combined
in treating primary sclerosing cholangitis.