FP-LAD, also known as fluoro-PRO-LAD or as TRALA-16, is a serotonin receptor modulator of the lysergamide family related to lysergic acid diethylamide (LSD; METH-LAD). It is specifically a fluorinated derivative of PRO-LAD (6-propyl-6-nor-LSD) and an analogue of FLUORETH-LAD (FE-LAD; 6-ethyl-6-nor-LSD).
The drug has been reported to act as a potent ligand of the serotonin 5-HT<sub>2</sub> receptors. It had affinities (K<sub>i</sub>) of 0.93nM at the serotonin 5-HT<sub>2A</sub> receptor, 1.8nM at the serotonin 5-HT<sub>2B</sub> receptor, and 3.7nM at the serotonin 5-HT<sub>2C</sub> receptor. FP-LAD was assessed and found to be a full agonist of the serotonin 5-HT<sub>2A</sub> and 5-HT<sub>2C</sub> receptors, with and values of 0.48nM (93%) and 1.7nM (97%), respectively. It had several-fold greater activational potency than LSD at the serotonin 5-HT<sub>2A</sub> and 5-HT<sub>2C</sub> receptors.
The chemical synthesis of FP-LAD has been described.
FP-LAD was patented by Daniel Trachsel and Matthias Liechti and colleagues in association with MindMed (Mind Medicine) in 2023. It had also previously been described in an earlier patent by Andrew Kruegel in association with Gilgamesh Pharmaceuticals in 2022. Hamilton Morris has described synthesizing FP-LAD and/or 1P-FP-LAD with Lizard Labs in 2025. According to Morris, FP-LAD was active but had only about one-fifth of the potency of LSD.