Which medication is effective in managing hypertension in children with acute glomerulonephritis?

Captopril is an angiotensin-converting enzyme (ACE) inhibitor that plays a significant role in managing hypertension, particularly in children with acute glomerulonephritis. This condition often leads to fluid overload and increased blood pressure due to the kidneys' impaired ability to filter waste and manage fluid balance. Captopril helps lower blood pressure by relaxing blood vessels, reducing the workload on the heart, and improving kidney function, making it an appropriate choice in this situation.

The other medications listed do not effectively manage hypertension in this context. Digoxin is primarily used for heart failure and certain arrhythmias but is not a first-line treatment for hypertension. Diazepam is an anxiolytic that can be used for anxiety or muscle spasms but does not have properties that address elevated blood pressure. Phenytoin, an anticonvulsant, is used to control seizures and does not have any role in managing hypertension. Thus, the specific action of captopril in reducing blood pressure makes it the correct choice for treating hypertension in children with acute glomerulonephritis.