zendesk/zendesk_api_client_php

<?php
include("../../vendor/autoload.php");
use Zendesk\API\HttpClient as ZendeskAPI;

/**
 * Replace the following with your own.
 */
$subdomain = "subdomain";
$username = "email@example.com";
$token = "6wiIBWbGkBMo1mRDMuVwkw1EPsNkeUj95PIz2akv";
$client = new ZendeskAPI($subdomain);
$client->setAuth('basic', ['username' => $username, 'token' => $token]);
try {
    $result = $client->ticketFields()->update(51931448, ["custom_field_options"=> [
        [
          "name"=> "Apple Pie",
          "value"=> "apple_pie"
        ],
        [
          "name"=> "Pecan Pie",
          "value"=> "pecan_pie"
        ]
      ]
    ]);
    // Show result
    echo "<pre>";
    print_r($newOrganization);
    echo "</pre>";
} catch (\Zendesk\API\Exceptions\ApiResponseException $e) {
    echo 'Please check your credentials. Make sure to change the $subdomain, $username, and $token variables in this file.';
}