Capsules: Intro, Hard and soft gelatine capsules, Preparation
Capsules: An Introduction
Capsules are solid dosage forms in which medicinal agents and/or inert substances are enclosed in a small shell of gelatin. Gelatin capsule shells may be hard or soft, depend- ing on their composition. The shells may be composed of two pieces, a body, and a cap, or they may be composed of a single piece. Two-piece capsules are commonly referred to as hard-shell capsules, and one-piece capsules are often referred to as soft-shell capsules
Types of Capsules:
Hard gelatin capsules
Soft gelatin capsules
Hard Gelatin Capsule
Hard gelatin capsule shells are used in most commercial medicated capsules. They are also commonly employed in clinical drug trials to compare the effects of an investigational drug with those of another drug product or placebo. The community pharmacist also uses hard gelatin capsules in the extemporaneous compounding of prescriptions. The empty capsule shells are made of gelatin, sugar, and water. As such, they can be clear, colorless, and essentially tasteless
They may be colored with various FD&C and D&C dyes and made opaque. by adding agents such as titanium dioxide. Most commercially available medicated capsules contain combinations of colorants and opaquants to make them distinctive, many with caps and bodies of different colors
Capsule Size:
Empty gelatin capsules are manufactured in various lengths, diameters, and capacities. The size selected for use is determined by the amount of fill material to be encapsulated. The density and compressibility of the fill will largely determine to what extent it may be packed into a capsule shell
Cleaning and Polishing
Small amounts of powder may adhere to the outside of capsules after filling. The powder may be bitter or otherwise unpalatable and should be removed before packaging or dispensing. On a small scale, capsules may be cleaned individually or in small numbers by rubbing them with clean gauze or cloth. On a large scale, many capsule-filling machines are affixed with a cleaning vacuum that removes any extraneous material from the capsules as they exit the equipment
Soft gelatin capsules
Soft gelatin capsules are made of gelatin to which glycerin or polyhydric alcohol such as sorbitol has been added. Soft gelatin capsules, which contain more moisture than hard capsules, may have a preservative, such as methylparaben and/or propylparaben, to retard microbial growth. Soft gelatin capsules may be oblong, oval, or round. They may be single-colored or two-toned and may be im- printed with identifying markings. As with hard gelatin capsules, they may be prepared with opaquants to reduce transparency and render characteristic features to the capsule shell.
Soft gelatin capsules are used to encapsulate and hermetically seal liquids, suspensions, pasty materials, dry powders, and even pre-formed tablets. Soft gelatin capsules are pharmaceutically elegant and are easily swallowed.
Use of Soft Gelatin Capsules
Soft gelatin capsules are prepared to contain a variety of liquid, paste, and dry fills. Liquids that may be encapsulated into soft gelatin capsules include the following:
- Water-immiscible volatile and nonvolatile liquids such as vegetable and aromatic oils, aromatic and aliphatic hydrocarbons, chlorinated hydrocarbons, ethers, esters, alcohols, and organic acids
- Water-miscible nonvolatile liquids, such as polyethylene glycols, and nonionic surface-active agents, such as polysorbate 80
- Water-miscible and relatively nonvolatile compounds such as propylene glycol and isopropyl alcohol, depending on factors such as concentration used and packaging conditions
Liquids that can easily migrate through the capsule shell are not suitable for soft gelatin capsules. These materials include water above 5% and low molecular weight water-soluble and volatile organic compounds such as alcohols, ketones, acids, amines, and esters. Solids may be encapsulated into soft gelatin capsules as solutions in a suitable liquid solvent, suspensions, dry powders, granules, pellets, or small tablets.
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Suggested readings
Recommended readings:
Risk Management in AI-Enabled Medical Devices: A Critical Pillar of FDA Guidelines
Clarifying Device Description and Intended Use in AI-Enabled Medical Devices
Building Trust in AI-Enabled Medical Devices: A Comprehensive Approach to FDA Guidelines
