What does "X__D" indicate in a prescription?

In a prescription context, "X__D" typically refers to a frequency of administration where the medication is to be taken for a certain number of days. The "X" represents a numerical value that indicates how many times a day the medication should be taken, while the "D" stands for "days." This notation helps ensure proper adherence to the medication regimen, indicating that the patient should take the medication multiple times throughout the specified number of days.

Therefore, understanding this notation is crucial for patient compliance and effectiveness of the treatment, as it directly impacts how the drug is administered and monitored over a specified duration. The clarity of this instruction is vital in preventing misunderstandings regarding the treatment regimen.