Chapters 190 and 192

What is the primary mechanism of action of methotrexate (MTX)?

• Blocks T-cell activation by suppressing IL-2

• Inhibits dihydrofolate reductase, interfering with folate metabolism

• Inhibits protein synthesis by binding to ribosomes

• Promotes DNA crosslinking during replication

A patient is being considered for azathioprine therapy. Genetic testing reveals they have low thiopurine methyltransferase (TPMT) enzyme activity (5.0–13.7 U). According to guidelines, what is the most appropriate course of action?

• Consider reducing the dose to 0.5 mg/kg or choose an alternative medication

• Discontinue azathioprine permanently

• Increase the dose to overcome low metabolism

• Proceed with standard dosing of 2.0–3.0 mg/kg

Which of the following patient conditions is a contraindication to initiating cyclophosphamide therapy?

• History of systemic lupus erythematosus

• Prior use of corticosteroids

• Severe photosensitivity

• Transitional cell carcinoma of the bladder

Which of the following cytotoxic agents used in dermatology works by inhibiting ribonucleotide diphosphate reductase and is associated with dermatomyositis-like skin reactions?

• Cyclophosphamide

• Hydroxyurea

• Methotrexate

• Thioguanine

Which of the following cytotoxic agents is commonly associated with both nail hyperpigmentation and eccrine gland complications, such as neutrophilic eccrine hidradenitis (NEH)?

• Bleomycin

• Cyclophosphamide

• Cytarabine

• Vincristine

Which of the following drugs increase cyclosporine concentration?

• Azithromycin

• Carbamazepine

• Rifampin

• Terbinafine

What is the FDA-approved indication of topical tacrolimus?

• 0.1% ointment for 2-15 years old with moderate to severe AD

• 0.03% ointment for adults with moderate to severe AD

• 1% cream for 3 months-23 months old with moderate AD

• 0.1% ointment for severe vitiligo

A PV patient was referred to your clinic for management. You plan to give him the immunosuppressive medication that inhibits inosine monophosphate dehydrogenase resulting to decrease in T- and B-cells. What is the daily dosing regimen for this patient?

• 10-15mg/kg

• 25-35mg/kg

• 35-55mg/kg

• 50-60mg/kg

Which of the following interacts with cyclosporine resulting to increased risk of nephropathy?

• Bosentan

• Nafcillin

• Phenytoin

• TMP-SMX

Which of the following is an absolute contraindication to the use of Mycophenolate Mofetil (MMF)?

• Severe renal dysfunction

• Deficiency of hypoxanthine-guanine phosphoribosyl transferase enzyme

• Known hypersensitivity to MMF

• Concomitant corticosteroid therapy