Inhibition of Aggressive Behavior in Participants With Fragile X Syndrome

The goal of this clinical trial is to learn if drug SRX246 works to treat irritability, agitation, aggression and self-injury (IAAS) behaviors in adult males with Fragile X Syndrome (FXS). It will also learn about the safety of drug SRX246. The main questions it aims to answer are: * Does drug SRX246 lower the number of times participants experience IAAS behaviors? * What medical problems do participants have when taking drug SRX246? Researchers will compare drug SRX246 to a placebo (a look-alike substance that contains no drug) to see if drug SRX246 works to treat IAAS behaviors. Participants will: * Take drug SRX246 or a placebo every day for up to 8 months * Have weekly checkups by phone or video to answer study questions * Have periodically scheduled home visits by nurses to conduct medical check-ups and tests * Keep a diary of their symptoms