updating rst2pdf leads to pip uninstall

I had some problem generating PDF files from reStructuredText, which I thought I could solve with updating rst2pdf. I got a Permission denied error when I did pip install -U rst2pdf

      OSError: [Errno 13] Permission denied: '/usr/local/lib/python2.7/dist-packages/pip-6.0.8.dist-info/DESCRIPTION.rst'

$ sudo !!
sudo pip install -U rst2pdf
[sudo] password for root: 
sudo: pip: command not found
$ pip install -U rst2pdf
pip: command not found

How can I solve this, and how to prevent it from happening again?