A 48-year-old woman with bipolar I disorder is on lithium monotherapy. Her serum lithium level is 1.1 mEq/L (therapeutic range 0.6–1.2 mEq/L), and she has normal renal function. She complains of polyuria, polydipsia, and nocturia. Urine osmolality is 150 mOsm/kg (normal >800 mOsm/kg). What is the drug of choice to manage her lithium-induced nephrogenic diabetes insipidus?