dynamically load a datatable in an array instead of writing the list manually

for a drug-drug interaction software, the following code contains an array for drugs/ medications that will appear in the autocomplete list.

<System.Web.Services.WebMethodAttribute(), System.Web.Script.Services.ScriptMethodAttribute()>
   Public Shared Function GetCompletionList(ByVal prefixText As String, ByVal count As Integer, ByVal contextKey As String) As String()
       ' Create array of Drugs


       Dim drugs() As String = {"Methotrexate", "Mannitol", "Allopurinol", "Aspirin", "Vitamin A", "Vitamin C", "Vitamin D", "Vitamin E", "Amoxicillin", "Mercaptopurine", "Diclofenac"}

       ' Return matching drugs
       Return (
           From m In drugs
           Where m.StartsWith(prefixText, StringComparison.CurrentCultureIgnoreCase)
           Select m).Take(count).ToArray()
   End Function

i need a way to dynamically load a datatable of 5,000 medication in this array instead of writing the medication list manually

Dim druggv As New GridView
       druggv.DataSource = drugsds
       druggv.DataBind()
       Dim i As Integer = druggv.Rows.Count
       For x = 0 To i - 1
           Dim singleItem As String = druggv.Rows(x).Cells(1).Text.ToString
           Dim list As String = list + ", " + singleItem

       Next