$re = '~(?:(^|,)(?i:[а-яё]()|[^,])*+(?!\2))+,?~u';
$str = '42 year old, blonde, car, good green tree on field, правильное решение12, данных не больше 3, look what you\'ve done 4 times, pose 74, рисунок 12
привет, bobby, частота кадра 60fps, привет,';
$subst = "";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
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