Drop/ Alter index if exist

Hi every body

 there is some way to delete or rename an index only if this index exists?

something like

"alter index index rename to pepe if exists"

thanks

--
Pau Marc Muñoz Torres

Laboratori de Biologia Computacional  
Institut de  Biotecnologia   i Biomedicina Vicent Villar                                    
Universitat Autonoma de Barcelona
E-08193 Bellaterra (Barcelona)
             
telèfon: 93 5812807
Email : paumarc.munoz@bioinf.uab.cat