ho provato ma non funge.
questo è il codice della mia pagina:

<form action="https://www.federfarma.it/bdf/ricerca/ricerca.asp" method="get">
<label>Nome farmaco <input name="_ctl0:MainContent:LeftColumn:CMSUSERCONTROL_ 3:txtDrugsKey" type="text" id="_ctl0_MainContent_LeftColumn_CMSUSERCONTROL_3_ txtDrugsKey" onkeydown="if(event.which || event.keyCode){if ((event.which == 13) || (event.keyCode == 13)) {document.getElementById('_ctl0:MainContent:LeftCo lumn:CMSUSERCONTROL_3:doSearchDrugs').click();retu rn false;}} else {return true}; " /></label>
<input type="submit" name="_ctl0:MainContent:LeftColumn:CMSUSERCONTROL_ 3:doSearchDrugs" value="cerca" id="_ctl0_MainContent_LeftColumn_CMSUSERCONTROL_3_ doSearchDrugs" />
</form>