Excipients in Pharmaceutical Tablets

 Excipients in Pharmaceutical Tablets

•     Fillers and Diluents: Fillers or diluents add bulk to the tablet formulation, ensuring accurate dosing and uniform tablet properties. Examples include:

•        Lactose: Commonly used due to its good compressibility and blending properties.

•  Microcrystalline Cellulose: Provides compressibility, uniformity, and good flow properties.

•        Calcium Phosphate: Used as a filler in both wet and dry granulation processes.

•     Mannitol: Offers cooling sensation when chewed, commonly used in chewable tablets.

•        Starch: Used as a filler in tablet formulations.

 

•   Binders: Binders are used to hold the tablet ingredients together, ensuring that the tablet maintains its shape and integrity. They also aid in granulation, making it easier to form tablets during compression. Examples include:

•        Starch: Often used as a natural binder.

•   Cellulose Derivatives: Hydroxypropyl cellulose and hydroxypropyl methylcellulose provide good binding properties.

•     Polyvinylpyrrolidone (PVP): A synthetic binder that forms a flexible film around the particles, promoting cohesion.

•        Gelatin: A natural binder used in soft gelatin capsules and chewable tablets.

•        Sucrose: Used as a binder in effervescent tablets.

 

•     Disintegrants: Disintegrants help the tablet break down into smaller particles when it comes into contact with fluids in the gastrointestinal tract. This enhances drug dissolution and absorption. Examples include:

•    Croscarmellose Sodium: A superdisintegrant that swells rapidly upon contact with water, leading to tablet disintegration.

•       Sodium Starch Glycolate: Absorbs water and swells, causing mechanical breakup of the tablet.

•  Cross-Linked Polyvinylpyrrolidone (Crospovidone): Swells and disrupts tablet structure, aiding disintegration.

•    Microcrystalline Cellulose: Provides mechanical resistance to tablets, facilitating controlled disintegration.

 

•        Lubricants: Lubricants reduce friction between the tablet formulation and the tablet press tooling, preventing sticking and ensuring smooth tablet ejection. Examples include:

•        Magnesium Stearate: One of the most common lubricants in tablet manufacturing.

•        Stearic Acid: Provides lubrication and also contributes to tablet hardness.

•        Sodium Lauryl Sulfate: Acts as a lubricant and a wetting agent during granulation.

•        Talc: Offers lubrication and improves powder flow during tablet compression.

•        Polyethylene Glycol (PEG): Used as a dry lubricant for water-sensitive drugs.

 

•        Glidants: Glidants improve the flow of powders by reducing interparticle friction, ensuring uniform powder distribution during tablet compression. Examples include:

•        Colloidal Silicon Dioxide: Improves powder flow and prevents agglomeration.

•        Talc: Acts as a glidant when used in small quantities.

•        Starch: Used as a glidant in some formulations.

•        Calcium Phosphate: Can enhance powder flow properties.

 

•    Colorants: Colorants are added to tablets to enhance their appearance and facilitate product identification. They can be natural or synthetic compounds. Examples include:

•        Iron Oxide Pigments: Provide various shades of red, yellow, and black.

•        Titanium Dioxide: Used as a white colorant.

•        FD&C and D&C Dyes: FDA-approved colorants with specific codes.

•        Natural Colorants: Extracts from natural sources like fruits and vegetables.

 

•        Flavoring Agents: Flavoring agents are added to enhance the taste of chewable tablets or orally disintegrating tablets, improving patient acceptability. Examples include:

•        Artificial and Natural Flavors: Range from fruity to minty flavors.

•        Sweeteners: Aspartame, sucrose, and other sweeteners can mask the bitterness of certain drugs.

 

•      Coating Agents: Coating agents are used to apply a protective layer around the tablet, enhancing stability, appearance, and ease of swallowing. Examples include:

•        Hydroxypropyl Methylcellulose (HPMC): Forms a clear, flexible film coating.

•        Ethyl Cellulose: Provides a water-resistant barrier.

•        Polyvinyl Alcohol: Forms a clear, glossy coating.

•        Shellac: Used for enteric coatings and immediate-release coatings.

•        Opadry Coatings: Proprietary mixtures that offer various colors and functionalities.

 

•        Enteric Coating Agents: Enteric coatings protect the tablet from disintegrating in the stomach, preventing drug degradation by stomach acid. Examples include:

•        Cellulose Acetate Phthalate: Forms an enteric coating when properly formulated.

•        Acrylate Polymers: Provide pH-dependent dissolution behavior.

•    Hydroxypropyl Methylcellulose Phthalate: Offers acid resistance and targeted drug release.

 

•     Sustained-Release Agents: Sustained-release agents control the drug's release over an extended period, maintaining therapeutic levels. Examples include:

•        Hydroxypropyl Methylcellulose (HPMC): Forms gel matrix to control drug diffusion.

•        Ethyl Cellulose: Forms water-insoluble barriers for sustained release.

•        Methacrylic Acid Copolymers: pH-dependent and time-controlled release.

•        Polyvinyl Acetate: Used in matrix systems for controlled release.

 

•   Effervescent Excipients: Effervescent excipients create a reaction when in contact with water, leading to carbon dioxide generation. This enhances drug dissolution and can improve patient compliance. Examples include:

•        Citric Acid: Provides acidity for the effervescent reaction.

•        Sodium Bicarbonate: Releases carbon dioxide gas when dissolved in water.

•        Tartaric Acid: Enhances effervescence in combination with citric acid.

 

•      Super disintegrants: Super disintegrants aid in rapid tablet disintegration, ensuring the drug is released quickly for absorption. Examples include:

•        Croscarmellose Sodium: Swells rapidly and disrupts tablet structure.

•        Sodium Starch Glycolate: Provides rapid disintegration due to swelling.

•        Cross-Linked Polyvinylpyrrolidone (Crospovidone): Promotes rapid tablet breakup.

 

•        Antioxidants: Antioxidants are added to formulations to prevent degradation of the drug due to oxidation. Examples include:

•        Ascorbic Acid: A natural antioxidant that can stabilize susceptible compounds.

•        Tocopherols: Vitamin E derivatives with antioxidant properties.

•        Butylated Hydroxyanisole (BHA) and Butylated Hydroxytoluene (BHT): Synthetic antioxidants that inhibit oxidation