The PMHNP is assessing a 49-year-old male with a history of depression, post-traumatic stress disorder (PTSD), alcoholism with malnutrition, diabetes mellitus type 2, and hypertension. His physical assessment is unremarkable with the exception of peripheral edema bilaterally to his lower extremities and a chief complaint of pain with numbness and tingling to each leg 5/10. The PMHNP starts this patient on a low dose of doxepin (Sinequan). What is the next action that must be taken by the PMHNP? 

a) Orders liver function tests

b) Educate the patient on avoiding grapefruits when taking this medication

c) Encourage this patient to keep fluids to 1500ml/day until the swelling subside

d) Order BUN/Creatinine test