The presently disclosed subject matter provides compounds of the formula, formula (Ia): and pharmaceutically acceptable salts thereof, wherein R1, R2, R3, R4, R5, X, Y, and n are as defined herein. Also disclosed are methods for making the compounds of the formula as set forth hereinabove, their use in inhibiting acid ceramidase and ceramidase-related activity, and their use as drugs and prodrugs in the treatment and/or prevention of diseases associated with undesirable ceramidase or sphingosine kinase activity, including, but not limited to, cancer, cancer metastasis, atherosclerosis, stenosis, inflammation, asthma, and atopic dermatitis.