168
O. D. Putra and H. Uekusa
Fig. 9.12 a Tabletability profiles and b elastic recovery as a function of compaction pressure of
DES (red) and DES-BA (blue). Reprinted from [72]. Copyright 2012, with permission from Elsevier
are considerably important for the tabletability of the DES-BA salt multicomponent
crystal.
The tabletability profiles of DES and DES-BA as a function of compaction pressures between 25 and 350 MPa are shown in Fig. 9.12a. The tensile strength of
the DES tablet was lower than that of the DES-BA tablet: it started at ~0.9 MPa
at a 25 MPa compaction pressure, maintained ~1.6 MPa at a 250 MPa compaction
pressure, and decreased at compaction pressures higher than 250 MPa. The tensile
strength of DES tablets was poor (<1 MPa) at compaction pressures below 150 MPa.
However, DES can form a relatively suitable tablet at compaction pressures between
150 and 250 MPa. Surprisingly, DES-BA generated better tabletability profiles than
DES. DES-BA could be made into a suitable tablet until 350 MPa, which is the
highest compaction pressure employed in this study. Furthermore, a tensile strength
above 2 MPa could be attained at compaction pressures exceeding 200 MPa. It should
be noted that a minimum tensile strength of 2 MPa has been proposed for ensuring the
integrity of a pharmaceutical tablet. Therefore, a DES-BA formulation will probably
have no substantial tabletability problems—even at high compaction pressures.
The elasticity-plasticity profiles of DES and DES-BA were investigated afterward. Plasticity and elasticity are defined by the elastic recovery in this case. The
profiles of elastic recovery under different compression pressures are presented in
Fig. 9.12b. The elastic recovery of DES gradually increased up to a compaction
pressure of 150 MPa and decreased at higher compaction pressures. Therefore, an
elastic recovery depletion tendency was observed in DES with increasing compaction
pressures. We predicted that corrugated or interlocked hydrogen-bonded structures
in the DES parent drug were responsible for the depletion of elastic recovery. By
comparing the elastic recoveries of DES and DES-BA, the novel multicomponent
crystal reported in this study is considerably more plastic than the parent drug; this
may suggest that a DES-BA tablet has lower porosity and is stronger than a DES
tablet for the same compaction pressures.
A tendency for capping was observed in the DES tablet if the compaction pressure
was increased above 250 MPa (Fig. 9.13a). Such profiles are called ‘over-compaction’
O. D. Putra and H. Uekusa
Fig. 9.12 a Tabletability profiles and b elastic recovery as a function of compaction pressure of
DES (red) and DES-BA (blue). Reprinted from [72]. Copyright 2012, with permission from Elsevier
are considerably important for the tabletability of the DES-BA salt multicomponent
crystal.
The tabletability profiles of DES and DES-BA as a function of compaction pressures between 25 and 350 MPa are shown in Fig. 9.12a. The tensile strength of
the DES tablet was lower than that of the DES-BA tablet: it started at ~0.9 MPa
at a 25 MPa compaction pressure, maintained ~1.6 MPa at a 250 MPa compaction
pressure, and decreased at compaction pressures higher than 250 MPa. The tensile
strength of DES tablets was poor (<1 MPa) at compaction pressures below 150 MPa.
However, DES can form a relatively suitable tablet at compaction pressures between
150 and 250 MPa. Surprisingly, DES-BA generated better tabletability profiles than
DES. DES-BA could be made into a suitable tablet until 350 MPa, which is the
highest compaction pressure employed in this study. Furthermore, a tensile strength
above 2 MPa could be attained at compaction pressures exceeding 200 MPa. It should
be noted that a minimum tensile strength of 2 MPa has been proposed for ensuring the
integrity of a pharmaceutical tablet. Therefore, a DES-BA formulation will probably
have no substantial tabletability problems—even at high compaction pressures.
The elasticity-plasticity profiles of DES and DES-BA were investigated afterward. Plasticity and elasticity are defined by the elastic recovery in this case. The
profiles of elastic recovery under different compression pressures are presented in
Fig. 9.12b. The elastic recovery of DES gradually increased up to a compaction
pressure of 150 MPa and decreased at higher compaction pressures. Therefore, an
elastic recovery depletion tendency was observed in DES with increasing compaction
pressures. We predicted that corrugated or interlocked hydrogen-bonded structures
in the DES parent drug were responsible for the depletion of elastic recovery. By
comparing the elastic recoveries of DES and DES-BA, the novel multicomponent
crystal reported in this study is considerably more plastic than the parent drug; this
may suggest that a DES-BA tablet has lower porosity and is stronger than a DES
tablet for the same compaction pressures.
A tendency for capping was observed in the DES tablet if the compaction pressure
was increased above 250 MPa (Fig. 9.13a). Such profiles are called ‘over-compaction’