Fun fact, there (was?) is a isomer of methamphetamine that is actually over the counter, levomethamphetamine was often found in Vicks brand inhalers, though they appear to be discontinued, being replaced with a ‘non-medicated’ version. There are apparently generic inhalers that still do contain it though.
https://www.science.org/content/blog-post/other-methamphetam...
See also selegiline, which partially metabolizes to levoamphetamine and levomethamphetamine. Not OTC though (antidepressant).