While this list is monitored, you should know that there are many questionable open-access publishers who do not screen articles for quality or scientific rigor, and who charge very large author fees. So be cautious about content and be especially cautious about submitting articles for publication.
The number of Open Access drug & alcohol journals is growing but their contents represent only a fraction of the research that is freely available through more broadly based medical, health sciences, and social sciences journals. If you just want to search for content on a specific topic, the journal articles link is a better option.