You can use Dadavit for 90 or more days without problems. We have trials that show it. D-Aspartic Acid is sure [what the Italien correspondent meant was "safe"] also if you use 5.2 g everyday for a long time. D-Aspartic Acid is an endogenous amino acid found in the nervous and endocrine system of various invertebrates and vertebrates. Lh and testosterone are significantly increased in 12 days,but if you use D-aspartic to improve spermatozoa you have to use it for 90 days.On a side note: Predator Nutrition is to my knowledge the first European supplement retailer to stock bulk D-Aspartic Acid. If you look for cheaper alternatives to Dadavit or Primordial Performance's Testosterone Conversion Factor (unfortunately a PN-exclusive in Europe and consequently pretty pricely) you might want to check this out.
If you insist on Na-bound, highly soluble D-Aspartic Acid you can still dissolve it in water by adding some sodium bicarbonate (i.e. baking soda)