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A 65-year-old Caucasian man is started on azathioprine for the treatment of bullous pemphigoid. Upon review of his laboratory work at his 2-month follow-up appointment, you note a WBC of 3000/mm3 and a hemoglobin of 9 g/dL. He tells you he was recently started on a new medication by his primary care physician for joint pain. Which of the following medications was most likely started?

A. Naproxen

B. Colchicine

C. Acetaminophen

D. Allopurinol

E. Prednisone

D. Allopurinol. Increased risk of bone marrow suppression may occur with concomitant use of azathioprine and allopurinol. Allopurinol inhibits xanthine oxidase, thus shunting more 6-MP to the HGPRT pathway. This creates an excess of toxic purine analogs and results in increased risk for myelosuppression. If azathioprine is to be given to patients taking allopurinol, the dose must be markedly reduced.

A 75-year-old African-American man presents for evaluation of a bilateral lower extremity rash. His rash is most consistent with stasis dermatitis and you start treatment with triamcinolone 0.1% ointment. At his follow-up appointment in 6 weeks, his condition is significantly worse and you are concerned about allergic contact dermatitis. Which of the following should be used to screen for allergy to triamcinolone?

A. Budesonide

B. Tixocortol-21-pivalate

C. Hydrocortisone-17-butyrate

D. Clobetasol-17-propionate

E. Desoximetasone

A. Budesonide. The patch test screening agent for suspected contact allergy to triamcinolone, a member of structural Class B, is budesonide. Tixocortol-21-pivalate is used to test for contact allergy to Class A corticosteroids, such as hydrocortisone acetate. Hydrocortisone-17-butyrate is the agent used to screen for allergy to Class D2 corticosteroids, such as hydrocortisone valerate. Clobetasol-17-propionate is used to test for contact allergy to Class D1 corticosteroids, which include betamethasone.

You start a patient on dapsone for dermatitis herpetiformis. Which of the following drugs, when given concomitantly, may reduce the risk of methemoglobin formation?

A. Ranitidine

B. Vitamin C

C. Cimetidine

D. Zinc

E. Folic acid

C. Cimetidine. Both cimetidine and vitamin E have been shown to reduce the risk of methemoglobin formation in patients taking dapsone by reducing the hepatic oxidation of dapsone to hydroxylamine.

A 55-year-old Asian man ...

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