Which of the following medicines does NOT need to be withheld if a patient has a dehydrating illness?

• A. Edoxaban
• B. Lisinopril
• C. Metformin
• D. Furosemide

Answer: (A)

When a patient has a dehydrating illness, the safety concern centers on how reduced circulating volume and potential renal impairment affect drug clearance and risk of adverse effects. Drugs that can worsen dehydration or rely heavily on stable renal function are the ones you typically withhold. Lisinopril (an ACE inhibitor) can reduce renal perfusion further and lower blood pressure during dehydration, so it’s usually held. Metformin carries a risk of lactic acidosis when renal function is compromised or perfusion is reduced, so it’s held as well. Furosemide is a diuretic that can worsen volume depletion, making withholding appropriate in dehydration.

Direct oral anticoagulants like edoxaban, while they carry a bleeding risk, are not automatically withheld solely because of dehydration. The decision hinges more on the patient’s bleeding risk and renal function rather than dehydration by itself. If rehydration improves perfusion and renal function, anticoagulation can be continued or resumed in many cases. Therefore, in the context of dehydration alone, edoxaban is the one that does not require automatic withholding, compared with the other medications listed.