Zoloft is designed to help those who suffer from depression, anxiety, Metformin without a prescription drug or obsessive compulsive disorder. It is part of Metformin without a prescription drug class of drugs called selective serotonin reuptake inhibitors. The mechanism by which Zoloft works is not fully understood although what researchers do know is that it works by increasing the level of serotonin in the brain by inhibiting its breakdown.