Tablets and capsules are two of the most widely used oral medication forms. While both deliver medicine, they differ in structure, manufacturing, and how they interact with the body.
Understanding Tablets
A tablet is a solid dosage form created by compressing powdered ingredients. This process binds the active pharmaceutical ingredient (API) with excipients. These excipients help give the tablet its shape, strength, and ability to break down effectively.
Tablets come in many shapes and sizes, often round, oblong, or disc-shaped. Some are scored with a line, allowing them to be easily split for a smaller dose. Many also feature coatings to improve taste, ease swallowing, protect ingredients, or control drug release.
Understanding Capsules
A capsule is a solid dosage form where medication is enclosed within a soluble shell. It typically contains the active ingredient as a powder, granules, liquid, or gel. There are two primary types: hard-shelled and soft-shelled capsules.
Hard-shelled capsules, often two pieces (a body and a cap), usually contain dry powders or pellets. Soft-shelled capsules (softgels) are single, sealed units commonly used for oils, liquids, or active ingredients dissolved in oil. Both types are primarily made from gelatin (an animal protein) or plant-based alternatives like cellulose or pullulan.
Comparing Tablets and Capsules: Key Distinctions
Tablets are formed by compacting ingredients into a solid mass, while capsules involve filling a pre-formed shell with medication. This fundamental difference influences many characteristics. Tablets can often accommodate a higher dose due to their compressed nature.
Tablets vary widely in shape and size; some can be large or have rough edges, making them harder to swallow for some. Capsules, especially softgels, generally have a smooth, slippery texture and rounded shape, which can make them easier to swallow. However, both forms can present swallowing challenges.
Capsules are generally more effective at masking unpleasant tastes or odors because the medication is fully enclosed. While some tablets have coatings to mask taste, uncoated tablets can have a bitter taste if the active ingredient is unpalatable. Capsules tend to break down and release contents quickly, leading to faster absorption and onset of action. Tablets may absorb slower and can sometimes break down inconsistently.
In terms of stability and shelf life, tablets often have a longer shelf life and are more resistant to environmental factors like moisture and heat due to their solid, compressed nature. Capsules, especially softgels, can be more sensitive to humidity changes and may have a shorter shelf life. Manufacturing costs can vary, but tablets are generally less expensive to produce at high volumes due to efficient high-speed production techniques. Capsules may have higher raw material costs due to the shell, but can sometimes offer advantages in development time.
Factors Influencing Formulation Choice
The decision to formulate a medication as a tablet or a capsule depends on several considerations. The properties of the drug itself play a significant role; for instance, active ingredients sensitive to moisture or light might be better protected within a capsule shell. Some drugs may also be unstable in acidic stomach environments, influencing the choice of dosage form or requiring specialized coatings.
Patient needs are another important factor. For individuals who experience difficulty swallowing, a smooth capsule or a specially coated or chewable tablet might be preferred. Dosage flexibility is also considered; scored tablets allow for precise dose adjustments that are not possible with most capsules.
The desired release profile of the medication also guides the choice. Both tablets and capsules can be designed for immediate, delayed, or extended release, but the methods for achieving these profiles can vary between the two forms. Bioavailability, which refers to how much of the drug is absorbed into the bloodstream, is also considered, with capsules sometimes offering higher bioavailability. Finally, manufacturing efficiency and cost-effectiveness at scale are practical considerations for pharmaceutical companies.