Open AutoCAD & Send Command Using C#

private void Form1_Load(object sender, EventArgs e)

{           

string progID = "AutoCAD.Application.19";

AcadApplication acApp;

AcadApplication vAcadDoc;

if (Process.GetProcessesByName("acad").Length > 0)

{

acApp = (AcadApplication)Marshal.GetActiveObject(progID);

acApp.ActiveDocument.SendCommand("PURGE ");

}

else

{

acApp = new AcadApplication();

acApp = (AcadApplication)Marshal.GetActiveObject(progID);

acApp.ActiveDocument.SendCommand("PURGE ");

}                      

}