Capsules are a diverse dosage form prepared using different polymeric materials and using different methods. Two main types are commonly used, and they are classified according to the nature and flexibility of the capsule shell. While soft gelatin capsules are composed of a liquid or semisolid fill, hard capsules typically can contain either powder or beads. Analytical method development and validation go hand in hand with the determination of the drug release profile of capsule formulations during dissolution testing. The dissolution testing of both hard and soft gelatin capsules had been the focus of interest of an FDA-Industry Working Group. The mechanical properties of both gelatin and hypromellose capsule shells were studied by Missaghi and Fassihi. Based on its higher values of network of deformation and elastic modulus, gelatin appears to be a harder and tougher material than hypromellose. The capsule wall may comprise gelatin or another suitable polymer such as hypromellose also called hydroxypropylmethylcellulose (HPMC).