Researchers from Alicorn Pharmaceutical Co. Ltd. and Jiangsu Alicorn Pharmaceutical Co. Ltd. have disclosed crystalline salts of compounds acting as AP2-associated protein kinase 1 (AAK1) inhibitors that are potentially useful for the treatment of Alzheimer’s disease, bipolar disorder, Parkinson’s disease, diabetic peripheral neuropathy, postherpetic neuralgia (PHN) and schizophrenia.