As I said at another site... "Format" it out...
Code:
Dim My1stArray() As String, My2ndArray() As String, S As String
Dim LB As Integer, UB As Integer, LoopCnt As Integer

S = ":25:0186350587,:25:186350587,:25:86350587,:25:6350587,:25:350587,:25:50587,:25:587,:25:87,:25:7"

My1stArray = Split(S, ",")

LB = LBound(My1stArray)
UB = UBound(My1stArray)

For LoopCnt = LB To UB
  
  My2ndArray = Split(My1stArray(LoopCnt), ":25:")
  Debug.Print ":25:" & Format(My2ndArray(1), "0000000000")
  
Next LoopCnt


Good Luck