Binder – Pharmaceutical Excipients
Binder Excipients in the Pharmaceutical Industry
Binders play an important role in the tableting process of pharmaceuticals. They are used to improve the cohesion and plasticity of the powder mixture, which enhances the processability of the tablet and reduces the risk of tablet breakage during manufacture.
Peter C. Schmidt in Pharmazeutische Hilfsstoffe (1) explains binders: “From a technological point of view, pharmaceutical binders are “adhesives” designed to perform the following tasks: Increasing the particle size and, as a result, improving the flowability, reducing the bulk volume and the dust content of the mass to be processed, and, in the case of further processing into tablets or pellets, improving the plastic deformability.”
The quantity of binder excipient used in the tableting process varies depending on the specific application, but typically ranges from 2-10% of the tablet weight.
Binder are distinct from fillers and diluents, which have different functions in the tablet. Fillers are added to increase the bulk of the tablet, while diluents are added to reduce the potency of the active ingredient. Binder excipients, on the other hand, are added specifically to improve the tablet’s mechanical properties.
Binders can be of different origins and divided into (1)
- Natural Polymers: Arabic gum, Gelatin, Sodium Alginate, Pullulan, Starch, Pregelatinized Starch and Tragant
- Semi-Synthetic Polymers: Carboxymethylcellulose Sodium, Dextrin, Hydroxyethylcellulose, Hydroxypropylcellulose, Hypromellose, Maltodextrin, Methylcellulose
- Synthetic Polymers: Copovidone, Macrogols, Polyvinyl Alcohols (PVA), Povidone,
- Polymers with sustained release properties: Amino methacrylat-Copolymer (Type A), Amino methacrylat-Copolymer (Typ B), Celluloseacetate, Celluloseacetatbutyrate, Chitosan, Ethylcellulose, Polyacrylat-Dispersion 30 %, Poly(vinylacetat), Poly(vinylacetat)-Dispersion 30, Schellack, Zein
- Other Binders with sustained release properties: Fatty alcohols, Fat and Waxes, Hydrated Rizinius Oil, Stearic Acid
Many excipients can be used as binders. The main ones are
- Povidone (Polyvinylpyrrolidone, PVP)
- Hydroxypropyl cellulose (HPC)
- Microcrystalline cellulose (MCC)
- Polyethylene glycol (PEG)
- Gelatin
- Starch
- Carbomers
- Sodium carboxymethyl cellulose (NaCMC)
Definitions According to the European Pharmacopeia (Ph. Eur.) and USP/NF
- Povidone (Polyvinylpyrrolidone, PVP) Ph. Eur.: A water-soluble polymer that can be used as a binder excipient in tablet formulations. USP/NF: A water-soluble polymer that is used as a binder, lubricant, and disintegrant in tablet and capsule formulations.
- Hydroxypropyl cellulose (HPC) Ph. Eur.: A semi-synthetic cellulose derivative that is used as a binder, thickener, and emulsifier in pharmaceutical formulations. USP/NF: A cellulose derivative that is used as a binder, lubricant, and disintegrant in tablet and capsule formulations.
- Microcrystalline cellulose (MCC) Ph. Eur.: A purified form of cellulose that is used as a filler and diluent in tablet formulations. USP/NF: A purified form of cellulose that is used as a filler and diluent in tablet and capsule formulations.
- Polyethylene glycol (PEG) Ph. Eur.: A water-soluble polymer that can be used as a binder excipient in tablet formulations. USP/NF: A water-soluble polymer that is used as a lubricant and solubilizing agent in pharmaceutical formulations.
- Gelatin Eur.: A protein derived from collagen that is used as a binder and gelling agent in pharmaceutical formulations. USP/NF: A protein derived from collagen that is used as a binder and gelling agent in tablet and capsule formulations.
- Starch Eur.: A polysaccharide that is used as a binder and disintegrant in tablet formulations. USP/NF: A polysaccharide that is used as a binder, disintegrant, and thickener in tablet and capsule formulations.
- Carbomers Eur.: A family of water-soluble polymers that are used as thickening and emulsifying agents in pharmaceutical formulations. USP/NF: A family of water-soluble polymers that are used as thickening and emulsifying agents in topical and oral pharmaceutical formulations.
- Sodium carboxymethyl cellulose (NaCMC) Ph. Eur.: A cellulose derivative that is used as a binder and disintegrant in tablet formulations. USP/NF: A cellulose derivative that is used as a binder and thickener in pharmaceutical formulations.
In conclusion, binder excipients are essential components in the tableting process of pharmaceuticals. They improve the cohesion and plasticity of the powder mixture, enabling the manufacture of robust and uniform tablets. Binder excipients differ from fillers and diluents, which serve different functions in tablet formulations. A variety of excipients, including povidone, hydroxypropyl cellulose, microcrystalline cellulose, polyethylene glycol, gelatin, starch, carbomers, and sodium carboxymethyl cellulose, are commonly used in the pharmaceutical industry. The definitions of these excipients according to the European Pharmacopeia and USP/NF reflect their various applications in pharmaceutical formulations.
Binder Excipients on pharmaexcipients.com – in alphabetical order
References
(1) „Pharmazeutische Hilfsstoffe“ Peter C. Schmidt · Siegfried Lang