pChEMBL is defined as: -Log(molar IC50, XC50, EC50, AC50, Ki, Kd or Potency).
For instance, a value of 5 represents an activity of 10uM and values above this are more active. So, pChembl >5 is a good start.
To filter in the API use:
You might want to get all data where pChembl is present as a representative dataset. This is easy to do, just use: