Lubrication can strongly influence tablet characteristics like strength, disintegration and dissolution and thus should be performed appropriately taking properties of the materials into account. As magnesium stearate coats the particles, determination of the specific external surface area could be an approach to find the optimal lubricant amount to prevent sticking, to obtain a minimal reduction in strength and to generate a comparable lubrication between different dry granules and the starting powdered material. Therefore, in this study a surface proportional lubrication was investigated in comparison to a mass related internal and an external lubrication for five different materials (two types of microcrystalline cellulose, powder cellulose, magnesium carbonate and lactose). The specific external surface areas of different dry granules as well as of the starting powdered materials were determined. Prior to tableting an amount of magnesium stearate proportional to the specific external surface area (2.5 mu g/cm(2)) was added. For each material specific external surface area of the granules was smaller than that of the raw material. Hence, the amount of magnesium stearate added to the granules was much lower (0.1-0.25 (w/w) %) compared to the raw material (0.76-2 (w/w) %). Compaction curves for the granules showed a decrease in tensile strength of the corresponding tablets with increasing specific compaction force during roll compaction. Based on this work-hardening phenomenon, compression of the raw material should lead to the strongest tablets. In contrast to this, compactibility of direct compressed microcrystalline cellulose and powder cellulose was much lower compared to the granules. As both materials are lubricant sensitive, the added amount of magnesium stearate was too high and prevented particle bonding. For magnesium carbonate, compactibility of the raw material was still higher compared to the granules in spite of the tenfold lubricant quantity. Further experiments with equal amounts of magnesium stearate for powder and granules of magnesium carbonate were problematic, indicating an insufficient lubrication of the powdered magnesium carbonate in this case. External lubrication was practicable for all materials, brittle or plastically deforming, and resulted in the highest tablet tensile strength. As lubrication was in the same magnitude for different materials and lubrication proportional to the specific external surface area was not practicable for plastically deforming materials, external lubrication should be the method of choice. (C)2014 Elsevier B.V. All rights reserved.