Magnesium stearate is used as an excipient i.e. pharmacologically inactive compound in the formation of many tablets and capsules including weight reduction medications. This compound is formed by the incorporation of stearic acid in a magnesium ion.
This compound is added in the tablets and capsules to work as a lubricant, glidant, and anti-adherent. During a tablet formation, a lubricant decreases friction between the surface of the tablet and the wall of the die of the tablet producing machine, so that the tablets are easily ejected and the dies and punches of the machine are not damaged. A glidant improves the flow of the powdered drug by decreasing the inter-particulate friction. This gliding, anti-adherent, and lubrication properties of magnesium stearate are extremely important for the proper formation of tablets and capsules, otherwise the tablets will break and the powdered drug of the capsules will adhere to the machine which will result in decreased pharmacological activity of these medicines in the body.
However, magnesium state shouldn’t be used in large quantities for the formation of medicines as it’ll increase the disintegration time of these medicines in the stomach by forming a thick film onto the surface of the tablets and capsules, due to which more time is required by the digestive enzymes to dissolve this film and disintegrate the medicine.