Pharma gyan Pandit

Capsules physical stability

1.  Unprotected soft gelatin capsules rapidly reach equilibrium with the atmospheric conditions under which they are stored.

2.  This inherent characteristic warrants a brief discussion of the effects of temp and humidity on the products.

3.  General statements relative to the effects of temp and humidity on soft gelatin capsules must be confined to a control capsule that contains mineral oil with a gelatin shell having a dry glycerin to dry gelatin ratio of 0.5-1 and water to dry gelatin ratio of 1-1 and that is dried to equilibrium with 20-30% RH and 21-24^oC. 

The physical stability of soft gelatin capsules is associated primarily with the pick up or loss of water by the capsule shell .

If these are prevented by proper packaging ,the above controlled capsule should have satisfactory physical stability at S temp ranging from just above freezing to as high as 60⁰C.

As the humidity increases the moisture content  pickup of capsules increases.

 ex- 

At 30%RH at room temp shows that gelatin retain about 12% (48 mg) of water and glycerin 7% (14 mg)of water. At 60%RH the moisture content should be 17.4%. High humidity (>60%RH at 21-24⁰C) produce more lasting effects on the capsule shell.

Since as moisture is absorbed, the capsules become softer, tackier , and bloated.

The capsule manufacturer routinely conducts accelerated stability tests on new product as an integral part of the production development program.

The successful results are obtained by conducing at test conditions like

    80%RH at room temp in an open container

    40⁰C in open container

     40⁰C in closed container (glass bottle with tight screw cap)