how to get wordpress admin page content

<?php
$page_id = 53;
$post_id_53 = get_post($page_id);
$pagecontent = $post_id_53->post_content;
$pagecontent = apply_filters('the_content', $pagecontent);
$pagecontent = str_replace(']]>', ']]>', $pagecontent);
echo $pagecontent;
?>