In the management of antidiuretic hormone dysfunction, demeclocycline is given at which daily dosage?

• A. 600 mg/day
• B. 800 mg/day
• C. 1200 mg/day
• D. 1600 mg/day

Answer: (C)

Demeclocycline helps correct hyponatremia in SIADH by reducing the kidney’s response to ADH in the collecting ducts, leading to free-water diuresis. The usual adult dosing for this indication is 600 to 1200 mg per day, given in divided doses. To achieve a reliable effect while balancing safety, many clinicians use the higher end, about 1200 mg daily. Starting at 600 mg and titrating up to 1200 mg/day is common practice; using only 600 mg may be too small for some patients, while 1600 mg/day increases the risk of toxicity. Hence, 1200 mg/day is the typical, appropriate daily dose for management. Monitor sodium and kidney function and adjust as needed, keeping in mind potential adverse effects like nephrotoxicity and photosensitivity.