The NicTool PHP module utilizes the existing API with SOAP calls to retrieve, update, and manipulate DNS records. The available API calls can be referenced in the NicTool docs.
Just add the NicTool class to your project.
$nictool = new NicTool($location, $uri, $username, $password);
$zone_records = $nictool->get_zone_records(nt_zone_id);