A 42-year-old man is evaluated for nighttime cramping and crawling sensations in his calves. He experiences these symptoms in the late evening, especially when watching television or getting ready for bed. At times, he feels an urge to stand up and pace around the room, which provides brief relief of symptoms. He has had no pain, weakness, or excessive daytime sleepiness. His mother has similar symptoms. His only medication is loratadine for seasonal allergies.
On physical examination, vital signs are normal. No abnormal movements are noted, and testing of deep tendon reflexes and sensation shows no anomalies.
Results of standard laboratory testing include a normal complete blood count and a serum ferritin level of 120 ng/mL (120 µg/L).
Which of the following is the most appropriate treatment?