Lubrication properties of potential alternative lubricants, glycerin fatty acid esters, to magnesium stearate

To study the usefulness of glycerin fatty acid ester Poem TR-FB® (TR-FB) and Poem TR-HB® (TR-HB) as lubricants, pressure transmission ratio, ejection force, disintegration time, and tensile strength were measured at different concentrations and mixing times for granules and tablets. When each lubricant was mixed at 0.1–3.0%, the increase in the pressure transmission ratio that was equal to or greater than that of Mg-St as well as the reduction in the ejection force was observed at a low concentration in both TR-FB and TR-HB, proving that they have excellent lubrication performance. The granules that were lubricated with TR-FB and TR-HB at even low concentration of 0.4% showed a more stable and sufficiently lower ejection force than with Mg-St from the first tablet after the start of compression. When they were mixed for 5–60 min, while the mixture with Mg-St showed a low pressure transmission ratio of 82% and a high ejection force of 500 N in the first tablet even when the mixing time was 60 min, a high pressure transmission ratio and a low ejection force were observed in TR-FB and TR-HB from the first tablet after mixing for 5–60 min, and these were maintained thereafter. As for the disintegration time and the tensile strength, a prolonged disintegration time and a decreased tensile strength, which are disadvantages of Mg-St, were not observed in TR-FB and TR-HB. Based on these results, it was concluded that TR-FB and TR-HB are useful as alternative lubricants to Mg-St.