Solution:
You can use WP admin_footer
action hook to add custom js to the admin side. check below code. code will go in the active theme functions.php file.
function add_custom_admin_js(){
?>
<script type="text/javascript">
(function($){
$("#postbox-container-1").ready(function(){
alert("now what?");
$('p:contains("Poivre")').css('color', 'red');
});
})(jQuery);
</script>
<?php
}
add_action( 'admin_footer', 'add_custom_admin_js', 10, 1 );