use XML::LibXML;
my $dom = XML::LibXML->new(qw/ recover 2 /)->load_xml(  IO => $in );

for my $key ( $dom->findnodes( q{  /drug/* } ) ){
    print $key->nodeName, "\n", 
          $key->nodePath, "\n",
          $key->textValue, "###\n";
}