A 42-year-old woman presents to the emergency department with vaginal bleeding for the past 2 days. Her last menstrual period was 1 week ago and has had regular cycles. She has a history of a hydatidiform mole 8 years ago. A β-hCG is 20,000. The diagnosis of choriocarcinoma is made and she is started on methotrexate. What is the mechanism of action of methotrexate?

A 42-year-old woman presents to the emergency department with vaginal bleeding for the past 2 days. Her last menstrual period was 1 week ago and has had regular cycles. She has a history of a hydatidiform mole 8 years ago. A β-hCG is 20,000. The diagnosis of choriocarcinoma is made and she is started on methotrexate. What is the mechanism of action of methotrexate?

A 12-year-old boy cuts his hand on a soda can. He has a 5-cm laceration on the palmar aspect of his hand that will require suturing. The emergency department physician injects 1% lidocaine into the wound after careful cleansing with Betadine. The mechanism of action of lidocaine blocks which of the following modalities?

A 32-year-old woman found out 1 month ago that she has HIV disease. She began a HAART regimen after learning her HIV status. Now she presents with nausea, vomiting, and abdominal pain. Serum amylase is elevated. If her condition is related to her medications, which drug is most likely the cause of her symptoms?

A 23-year-old G1P0 woman at 34 weeks gestation presents to the labor and delivery floor with contractions. The contractions are intense and occurring regularly every 3 min. The physician wants to slow down the contractions and try to delay labor until betamethasone can be given. What medication would be most appropriate?

The pain of a 57-year-old man with metastatic colorectal cancer to liver, bone, and brain is an inpatient on the oncology service. He is managed with a morphine pump. However, he has become tolerant to morphine. Which of the following might be indicated to ameliorate his pain?