Magnesium stearate must be below what percentage in tablets and capsules?

• A. 0.5%
• B. 1%
• C. 2%
• D. 5%

Answer: (B)

Magnesium stearate is a lubricant used in tablet and capsule manufacturing to reduce friction and help ejection during production. However, because it is hydrophobic, using too much can coat the drug particles, hindering wetting and disintegration, which can slow dissolution and affect uniformity and bioavailability. To balance manufacturability with product quality, its amount is limited. The commonly accepted upper limit is about 1% by weight of the dosage unit, ensuring enough lubrication while minimizing impact on dissolution. Using more than 1% can noticeably slow dissolution and potentially alter drug release, so the safe maximum is 1%.