I am a nurse, i injected a patient with nur-isterate and had a needle prick on my finger. the patient tested negative. the prick was not deep but a little blood came out when i pressed my finger. i would like to know if i should start pep treatment?

Probably no PEP: If you're in US or other industrialized country, your workplace almost certainly has an infection control team (at least a nurse) and policies and they a) will want to know and b) will have the best advice for you. Contact them for direct advice. However, since the patient had a negative HIV test, you were not at risk and almost certainly should not take PEP. Hep B and C could be another mattter.