Potential Use of Magnesium Oxide as an Excipient to Maintain the Hardness of ODTs

This study aimed to clarify the effects of magnesium oxide (MgO) on the hardness of orally disintegrating tablets (ODTs) during storage. ODTs containing a range of MgO concentrations were prepared by direct powder compression and stored for up to 4 weeks in an unpackaged condition at 40°C, with 75% relative humidity. Tablets that did not contain MgO showed a significant decrease in hardness after one week in stor- age, while those containing MgO at a mass fraction of ≥4% maintained their hardness for up to 4 weeks. The tablet disintegration times after storage were equivalent to those observed before storage (approximately 30s), regardless of the MgO level. Furthermore, the dissolution behavior of a model drug (acetaminophen) from the ODTs was not affected by the level of MgO. These findings revealed that the addition of MgO sup- pressed the reduction in ODT hardness during storage in the unpackaged state, without delaying tablet dis- integration or inhibiting drug release.

Introduction
Orally disintegrating tablets (ODTs) are solid oral prepara- tions that disintegrate in mouth saliva or a small amount of water promptly, defined as within 30s by the U.S. Food and Drug Administration (FDA).This dosage form is very useful for infants, elderly people or patients with difficulty swallowing, and in patients with limited water intake.
Initial ODT formulations were relatively soft, and care was required during handling. However, recently developed ODTs have good disintegration properties and a higher level of hardness.However, ODTs contain strongly hydrophilic materials that absorb water and swell; therefore, exposure to moisture decreases tablet hardness, increasing the risk of cracking or chipping during handling. Therefore, it is important to ensure the quality of the preparation to minimize any reduction in tablet hardness due to moisture absorption. Several solutions to this problem using additives have been reported to date, but elaborate processing of the additives is required before tablet preparation. Further research is required to develop a convenient method of preparing an ODT that exhibits rapid disintegration while maintaining its hardness during storage under high humidity.
Magnesium oxide (MgO) is widely used as an effective and safe laxative and antacid. Previous studies have shown that the hardness of tableted MgO increases during storage under high humidity in the unpackaged state. We have previously investigated the inhibitory effect of MgO on the decrease in hardness during storage of tablets, and the mechanism underlying this effect. Download full article here: Potential Use of Magnesium Oxide as an Excipient to Maintain the Hardness of Orally Disintegrating Tablets during Unpackaged Storage

Article from Chem. Pharm. Bull. 67, 284–288 (2019) – Link to Paper