LY94939 was discovered as a result of efforts to develop agents that inhibit the uptake of 5-HT from the synaptic cleft. A selected analogue of LY94939, the compound LY82816 (3-p-trifluoromethyl-phenoxyN-methyl-3-phenylpropylamine oxalate or (fluoxetine oxalate), which was a secondary amine (later named as fluoxetine oxalate), and its primary amine or N-demethylated compound (later named as norfluoxetine), were the most potent inhibitors of [3 H]-5-HT uptake in nerve endings, with Ki values of 0.07 uM. The first salt form of fluoxetine tested in serotonin reuptake assays in the early 1970s was the oxalate salt (LY82816); however, the marketed version is the hydrochloride salt (fluoxetine hydrochloride (LY110140), or Prozac.