Formulation and modifying drug release from Hard and Soft Gelatin Capsules for Oral drug delivery

Abstract

Capsule is the most versatile of all dosage forms. Capsules are solid dosage forms in which one or more medicinal and inert ingredients are enclosed in a small shell or container usually made of gelatin. There are two types of capsules, “hard” and “soft”. The hard capsule is also called “two pieces” as it consists of two pieces in the form of small cylinders closed at one end, the shorter piece is called the “cap” which fits over the open end of the longer piece, called the “body”. The soft gelatin capsule is also called as “one piece”. Capsules are available in many sizes to provide dosing flexibility. Unpleasant drug tastes and odors can be masked by the tasteless gelatin shell. The administration of liquid and solid drugs enclosed in hard gelatin capsules is one of the most frequently utilized dosage. This proves the oral bioavailability of poorly soluble compounds, delivery of low and ultra-low doses of a compound using softgel also ensures decreased plasma variability. This has led to the commercial pharmaceutical and nutraceutical industries opting for the development of alternative shell forming materials instead of the traditional capsule shell material gelatin. This review discusses establishment and the ongoing development of the manufacturing technology for liquid and semisolid capsules with focus on progress and challenges of soft and hard gelatin capsules formulation in oral administration for improved solubility and as an absorption-enhancing technique. These considerations form a basis for new applications in oral drug delivery.