Several cellular targets have been proposed to be relevant to the therapeutic activity of topiramate.  These include (1) voltage-gated sodium channels ; (2) high-voltage-activated calcium channels ; (3) GABA-A receptors ; (4) AMPA/kainate receptors; and (5) carbonic anhydrase isoenzymes. There is evidence that topiramate may alter the activity of its targets by modifying their phosphorylation state instead of by a direct action.  The effect on sodium channels could be of particular relevance for seizure protection. Although topiramate does inhibit high-voltage-activated calcium channels, the relevance to clinical activity is uncertain. Effects on specific GABA-A receptor isoforms could also contribute to the antiseizure activity of the drug. Topiramate selectively inhibits cytosolic (type II) and membrane associated (type IV) forms of carbonic anhydrase. The action on carbonic anhydrase isoenzymes may contribute to the drug’s side-effects, including its propensity to cause metabolic acidosis and calcium phosphate kidney stones.
A thermogenic is a broad term for any supplement that the manufacturer claims will cause thermogenesis , resulting in increased body temperature, increased metabolic rate, and consequently an increased rate in the burning of body fat and weight loss. Until 2004 almost every product found in this supplement category comprised the " ECA stack ": ephedrine , caffeine and aspirin . However, on February 6, 2004 the Food and Drug Administration (FDA) banned the sale of ephedra and its alkaloid , ephedrine, for use in weight loss formulas. Several manufacturers replaced the ephedra component of the "ECA" stack with bitter orange or citrus aurantium (containing synephrine ) instead of the ephedrine.