Antidepressants are often used for chronic pain.

However, the ones that are most effective are the ones with mixed actions. Zoloft is primarily an SSRI and affects only serotonin reuptake.

The mixed ones are called SNRIs and affect norepi and serotonin.
They are Effexor, Cymbalta and Savella.

For PN primarily low dose tricyclics are often more effective.
The are amitriptyline and nortriptyline. There has been a study recently to show amitriptyline helps peripherall nerves regenerate. It is the only one so far with this potential discovered. All the other actions of the antidepressants are central, working in the brain to change your perception of pain.