| Summary: | Prediction of the tabletting behavior of powdered drugs is of great importance in the pharmaceutical industry. An instrumented hydraulic press and punch and die assembly were used to study compaction behavior of 5 widely used pharmaceutical materials, Avicel, Emcompress, spray-dried lactose, crystalline acetaminophen USP and acetaminophen DC granules. The hydraulic press was able to compress the above materials at compaction speeds comparable to those of rotary tablet presses. The compression cycle of the Betapress could not be duplicated by the hydraulic press since, with the hydraulic press, the displacement was not constant at peak pressure.
The compaction parameters measured by the hydraulic press were elastic recovery (ER), punch travel distance beyond peak pressure (D), punch travel time beyond peak pressure (PTT) decrease in the force during punch travel beyond peak pressure (F). The strength of the tablets was measured with a CT40 tablet hardness tester. D and PTT appeared to be measures of flow and bonding and to be useful parameters for the tabletting behavior of the above materials. In general, materials that displayed relatively
long D and PTT values formed coherent tablets regardless of their elastic recovery. Avicel which displayed the longest D and PTT values (and the largest recovery) formed the strongest tablets while crystalline acetaminophen USP displayed the shortest D and PTT values and did not form coherent compacts. Thus for particulate materials that were able to flow and bond, elastic recovery did not appear to play an important role in the tabletting process.
Avicel and spray-dried lactose displayed similar D and PTT values (ie. similar extent of flow and deformation) and Avicel's elastic recovery was about 3 times as much as of that of spray-dried lactose, but Avicel formed tablets that were about 5 times stronger than those of spray-dried lactose. Therefore the nature and number of bonds that are formed between the particles (which are related to the inherent property of the materials) appeared to be the most important factor in tablet formation.
The effects of peak pressure (Pmax) and average compression rate (ACR) were examined on the above parameters. Generally peak pressure influenced the elastic recovery, D, PTT and hence the strength of the tablets more than the average compression rate. === Pharmaceutical Sciences, Faculty of === Graduate
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