ABT-436

ABT-436, also known as xaliproden, was an experimental drug initially developed by Abbott Laboratories for the potential treatment of Alzheimer's disease. It is a selective 5-HT1A receptor agonist. The 5-HT1A receptor is a subtype of serotonin receptor, a G protein-coupled receptor that mediates the effects of serotonin, a neurotransmitter.

ABT-436 was investigated for its cognitive-enhancing properties in preclinical and clinical studies. The rationale behind its development was based on the hypothesis that stimulating 5-HT1A receptors could improve cognitive function, particularly in memory and learning, which are often impaired in Alzheimer's disease.

Despite showing some promise in early trials, ABT-436 ultimately failed to demonstrate sufficient efficacy in larger, phase III clinical trials to warrant regulatory approval. Development of the drug was discontinued. The reasons for the failure are complex and may involve factors such as patient selection, dosage regimens, and the overall complexity of Alzheimer's disease itself.