ABSTRACT
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Hard-shell capsules are a dosage form that is resorted to when a drug substance is poorly compressible in the desired dosage strength and is moisture-sensitive. It also, at times, results from decisions early in product development, during which original clinical trials were performed in capsules, because of convenience, and the trials went ahead too rapidly to economically change the dosage form. The time lapse between conception of a drug and its introduction into the market place is of importance, and even though hard-shell capsules may be more expensive and cause other problems not encountered in other solid-dosage forms, the development of the dosage form is easier and, in some aspects, more foolproof than direct compression-or wet granulation-based tablets (if those are possible with the drug substance). An example of a drug substance that was introduced into the market place as a capsule because the development got too far ahead of itself is chlordiazepoxide HCl (Librium Hydrochloride) capsules. Four years later, when the tablet, Libritabs, was introduced, the public was used to a capsule, and the tablets were never a success.
