Čes. slov. farm. 2008, 57(4):165-169

Characterization of microcrystalline celluloses by means of the parameters of a three-exponential compression equation

M. Řehula^*, T. Rysl

Charles University in Prague, Faculty of Pharmacy in Hradec Králové, Department of Pharmaceutical Technology

The study compares microcrystalline celluloses by means of the parameters of the three-exponential equation V/V₀ = A₁*exp(-P/t₁) + A₂*exp(-P/t₂) + A₃*exp(-P/t₃) + y₀¹). The process of compression, according to this equation, takes place in three stages: in the stage of reduction of interparticular pores, reduction of intraparticular pores, and in the stage of reduction of the solid substance without pores. The classic theory of compression is based on the fact that the individual processes take place within the ranges of concrete compression pressures. According to the new equations, the processes under evaluation take place concurrently within the whole range of compression pressures employed. The paper studied four microcrystalline celluloses, Avicels PH 102, PH 103, PH 105, and PH 301. These excipients differ in sizes and shapes of particles, density, and content of humidity. The evaluations included the sizes of reductions A_R, sizes of energies E_A, and "half-pressures" P_H. The results of the study show that with diminishing particles of microcrystalline celluloses energies E_A are decreased and "half-pressures" are simultaneously increased. Best compressibility was found in Avicel PH 102 with the value of the "half-pressures" of 119.954 MPa and the worst in Avicel PH 301 with the value of the "half-pressures" of 151.449 MPa.

Keywords: three-exponential equations of compression; microcrystalline celluloses; theory of compression of tablets

Grants and funding:

The study was financially supported by research project MSM 0021620822.

Received: June 19, 2024; Accepted: July 30, 2008; Published: April 1, 2008  Show citation