Isn't HCL Hydrochloric Acid? Is this some kind of binder to hold ingredients together? I'm just curious as I see this on commercials all the time.
Many drugs are practically insoluble in water, yet they are basic.
Such drugs, being bases, can react with acids to form salts. These salts, if properly chosen, can be quite water soluble. Very commonly, salts formed by reacting bases with hydrogen chloride or hydrochloric acid (HCl) are quite water soluble.
It is often important to have good water solubility in a drug to aid its dissolution in the stomach or to make it appropriate for percutaneous (injection, intravenous, etc.) use.
These hydrochloride salts are designated by listing "HCl" after the drug name.