Drupal: get all enabled dependencies for a module

gistfile1.php

<?php
function bit_get_enabled_dependencies($module) {
  $dependencies=array();
  // Get all module data so we can find dependencies and sort.
  $module_data = system_rebuild_module_data();
  // Get all dependencies for a module
  if (isset($module_data[$module])) {
    foreach ($module_data[$module]->required_by as $required_module => $required_module_data) {
      if (!in_array($required_module, $dependencies)) {
        if (module_exists($required_module)) {
          $dependencies[]=$required_module;
        }
      }
    }
  }
  return $dependencies;
}

dpm(bit_get_enabled_dependencies('privatemsg'));
dpm(bit_get_enabled_dependencies('panels'));