My rule of thumb, with a few choice exceptions, is that the 7.95 spent on antacids at the drug store would be better spent on more of your drug of choice. The majority of OTC potentiators will ,at best, in the utmost perfect circumstance, produce less than 10% of a boost in perceptible effects. This is just my opinion and my experience. I've tried them all and done them all and there is a short list of relatively obscure (mostly prescription) drugs that will majorly potentiate certain Opioids.
I'm closing this though, as it's been covered ad nauseum on the site in previous threads and it doesn't really relate in a meaningful way to Harm Reduction philosophy. It's more of a "how can I get the most out of my high" question, which we like to discourage here on the boards. There are a lot of other spots that are more receptive to and you might even way were built for questions and topics of this nature, like Reddit for instance.