In a 7-year-old child with primary nocturnal enuresis, which pharmacologic agent is best?

• A. Desmopressin (DDAVP)
• B. Paroxetine (Paxil)
• C. Lorazepam (Ativan)
• D. Hyoscyamine (Levsin)

Answer: (A)

Desmopressin is best because it directly lowers nighttime urine production by acting as a vasopressin analog. By stimulating V2 receptors in the kidney’s collecting ducts, it promotes water reabsorption and produces a smaller volume of urine during sleep. This targets the common mechanism behind primary nocturnal enuresis—nocturnal polyuria—making bedwetting less likely at night. It’s typically chosen for children around this age and can be effective even when behavioral strategies alone haven’t resolved the issue. Important safety notes: avoid excess fluid intake after dosing to minimize hyponatremia risk, and monitor for symptoms such as headache, nausea, or confusion. Other drugs listed don’t address nocturnal urine production and have little proven benefit for enuresis in children.