Male subject, 40 years age, with excellent physical health had come for surgery to place implant, He had taken a single prophylactic dose of 8?mg oral dexamethasone before 1 hour. He developed intermittent bouts of hiccups at a rate of roughly 5 to 7 per minute. It didn't reduce at all.

After 24 hours hiccups gradually decreased. What should be given to patients to treat chronic hiccups?