Metaxolone isn't scheduled and is generally not considered recreational so I'm going to close this.
For some reason people tend to think that most muscle relaxers are recreational but few are - the most common ones prescribed (cyclobenzaprine, tizanidine, methocarbamol, norphenadrine, etc.) have little to no recreational potential beyond potentiating other drugs.
The only truly recreational muscle relaxants are carbamate derivatives such as carisoprodol and meprobamate as well as benzodiazepines. Balofen (as a GABAb agonist) might have some limited recreational potential as well.