$statement = $pdo->prepare("INSERT INTO variablen ( formular, id_var, wert) VALUES (:formular, :id_var, :wert )");
foreach($einzelneVariablen AS $variable => $wert) {
$result = $statement->execute(array(
'formular' => 1,
'id_var' => $variable,
'wert' => $wert ));
}