Check if admin is editing page or custom post type

is_page() is not working on the admin area so I needed to use the following code

function this_screen() {
  $current_screen = get_current_screen();
  if( $current_screen ->id === "page" ) {
    include_once 'page_admin.php';
  }
}
add_action( 'current_screen', 'this_screen' );

You can replace “page” to any custom post type name