$re = '/\bdr[.\s]\s?/i';
$str = '"Dr. Drake Cohen" would become "Drake Cohen"
"Dr Drake Cohen" would become "Drake Cohen"
"Drake Cohen" would become "Drake Cohen"
"Rachel Smith" would become "Rachel Smith"
"Dr. Rachel Smith" would become "Rachel Smith"
alexandr the great';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php