Capsules are more expensive and can’t be easily split by patients so pills are generally preferred by manufacturers. Reasons to use capsules:
- they protect the medicine better from light and moisture and oxygen than tablets
- powder in capsules dissolves faster, more evenly and thus the dose can be frontloaded instead of spread out
- beads in capsules can be coated to control dosage rates or deliver one medication before another. I.e. if the active drug irritates the stomach a coating can counteract that or keep it from dissolving until it reaches the intestines. Extended release medications usually use these coatings to slow down absorption
- capsules can carry multiple physically separated chemicals that are too reactive to be allowed to touch
- the binders in the pill interfere with the medication
- capsules can mask the taste better
