USMLE Step 1

Question 1

What drugs cause drug-induced lupus? What is the difference between drug-induced lupus and SLE?

Answer 1

1. Hydralazine
2. Procainamide
3. Isoniazid

Drug-induced lupus forms antibodies against histones
SLE forms antibodies against ds-DNA

Question 2

Which drugs inhibits the Glutamine-PRPP amidotransferase?

Answer 2

1. 6-Merocaptopurine
2. Methotrexate
3. Azothioprine

Question 3

Which drug(s) inhibit IMP dehydrogenase during purine synthesis?

Answer 3

1. Ribavirin (antiviral)
   - Blocks IMP to GMP
2. Mycophenolate (immunosuppressant)
   - Particularly in white cells