This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Psychiatry
A 24-year-old woman has clear evidence of bipolar disorder. An adequate trial of lithium therapy has proved unsuccessful. Which of the following drugs would be most reasonable for her psychiatrist to prescribe next? 
Select and explain. 
A. Chlorpromazine, B. Carbamazepine, C. Alprazolam, D. Amitriptyline
B: Carbamazepine
Answer: B: Carbamazepine 
Explanation: A recent development in the pharmacologic treatment of affective disorders, especially bipolar disorder, has been the use of anticonvulsant drugs. The first to be tried, carbamazepine (Tegretol) often is the next line of treatment for bipolar disorder for persons unresponsive to lithium therapy. Carbamazepine has various side effects, although most are dose related and can be avoided by judicious clinical practice. The most worrisome side effect is aplastic anemia, which occurs very rarely but in an idiosyncratic manner. Ref: Kaplan et al, Page 553- 554