This study compares the drug loading capacity of Cellactose and two excipients of similar composition and similar particle size, prepared by dry granulation and extrusion-spheronization respectively. The drugs evaluated were acetaminophen and furosemide. Acetaminophen did not significantly affect the flow properties of any of the excipients, whereas furosemide markedly worsened flow properties, eliminating the differences initially existing among the three excipients. For both drugs, tablet mechanical properties were clearly better with Cellactose than with the other excipients. Acetaminophen dissolution rate was very similar regardless of the excipient used, but furosemide dissolution rate was lower from Cellactose tablets than from tablets prepared with the other excipients. This important difference is discussed in terms of micropore structure, specific surface area, and wettability of tablets, and is attributable to the special structure of Cellactose particles.