Private Declare Function ShellExecute Lib "shell32.dll" Alias "ShellExecuteA" ( _
  ByVal hwnd As Long, _
  ByVal lpOperation As String, _
  ByVal lpFile As String, _
  ByVal lpParameters As String, _
  ByVal lpDirectory As String, _
  ByVal nShowCmd As Long) As Long
 
Public Sub OpenDocument(File As String, Path As String)
    ShellExecute Form1.hwnd, "Open", Path & File, "", Path, 1
End Sub

Public Const "Textpfadende der zu erreichen ist vor der aufzurufenden Datei" As _
  String = "Textpfad von Laufwerk zum Textpfadende"

Private Sub Command9_Click()
OpenDocument "Datei die geöffnet werden soll.pdf", Path_"Textpfad aus Modul" & _
  "Constans"
End Sub