Hard gelatin capsules coloring

Hard gelatin capsules may be made hermetically sealed by the technique of banding wherein a film of gelatin, often distinctively colored, is laid down around the seam of the cap and body. Parke Davis KapsealR is a typical example. In the Quali-SealR process (Shionogi Qualicaps), two thin layers are applied, one on top of the... 

The effect of colored blisters can be even more dramatically seen when packaged, commercial, nifedipine capsules are studied. When stored outside of their protective blister package, the losses of the active content were substantial for both the soft and hard gelatine capsules. More than 20% of the drug substance... 

Iron oxides have been reported to make hard gelatin capsules brittle at higher temperatures when the residual moisture is 11-12%. This factor affects the use of iron oxides for coloring hard gelatin capsules, and will limit the amount that can be incorporated into the gelatin material. 

Hard gelatin capsules should be evaluated for appearance (including brittleness), color, odor of contents, assay, degradation products, dissolution, moisture, and microbial limits. Testing of soft gelatin capsules should include appearance, color, odor of contents, assay, degradation products, dissolution, microbial limits, pH, leakage, and pellicle formation. In addition, the till medium should be examined for precipitation and cloudiness. 

The capsule shell should be of the desired color, size, and brittleness. Traditional gelatin capsule shells should remain flexible. Under certain storage conditions, gelatin capsule shells can become hard and brittle. When the shells are squeezed between two fingers, a brittle shell will snap and in extreme cases shatter. Brittleness occurs due to cross-linking of the gelatin and this cross-linking adversely affects the dissolution of the capsule. Capsule color has also been known to fade over time. 

Capsules— These are primarily intended for oral administration and are solid preparations with hard or soft shells comprised of gelatin or hydrox-ypropyl methyl cellulose and small amounts of other ingredients such as plasticizers, fillers, and coloring agents. Their contents may be powders, granules, pellets, liquids, or pastes. 

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