Tablet binder or binding agent are the substances which are added either dry or in liquid form during wet granulation to form granules or to promote cohesive compacts for directly compressed tablets [1]. For example starch, pregelatinized starch, PEG, sorbitol, and HPMC, etc.
Tablet Binder and disintegrants have the opposite used in an oral solid formulation. Binder delay tablet disintegration while disintegrant increase tablet disintegration. Do you know the name of disintegrants used in pharmaceutical preparations? So, the proper amount of tablet binders is required for a proper formulation. They play a vital role in making sure pellets or granules and tablets remain in shape until they reach their target by holding all ingredients (API and Excipients) together in any solid dosage form. Selecting the correct binder is critical to maintaining the integrity of the tablet. Which is the desired release profile (immediate or modified) a formulator must know before choosing a binder?
Table of Contents
Classification of Tablet Binder
Based on their source:
- Natural: These are less toxicity, biodegradable, availability at low cost. Examples include starch, pregelatinized starch, Sodium alginate, and gelatin, etc.
- Synthetic/ Semisynthetic: These are the most widely used and required a low amount in a formulation. Examples include Polyvinyl Pyrrolidone (PVP), Methylcellulose, Hydroxy Propyl Methyl Cellulose (HPMC), Polymethacrylates, Sodium Carboxy Methyl Cellulose, Polyethylene Glycol (PEG) and Methylcellulose, etc.
- Saccharides and their derivatives: Disaccharides such as lactose and sucrose; Polysaccharides and their derivatives such as starches, cellulose or modified cellulose such as MCC and cellulose ethers such as hydroxypropyl cellulose (HPC); Sugar derivatives such as sorbitol, xylitol, and mannitol, etc.
Image of Carboxymethyl Cellulose
Based on their application in the manufacturing process:
Dry tablet binders : These are added to the powder blend, either after a wet granulation step or as part of a direct compression (DC) formula. Examples of Dry tablet binders include cellulose, Polyvinyl Pyrrolidone (PVP), Hydroxy Propyl Methyl Cellulose (HPMC), Sodium CarboxyMethyl Cellulose, Polyethylene Glycol (PEG), and Methyl Cellulose.
Solution tablet binders: These are used in wet granulation processes. These are dissolved in a different solvent such as water or isopropyl alcohol. Examples of Solution tablet binders include cellulose, gelatin, cellulose derivatives, polyvinyl pyrrolidone, starch, sucrose, mannitol, polyethylene glycol, and liquid glucose, etc.
Why Tablet Binder is necessary for Granulation?
During compression fine particles of power (both active and inactive ingredient) or granules must have two properties:
Firstly, Proper Flow property: Fine particles have fewer flow properties and thus, they make problems such as weight variation, segregation of powder particles during manufacturing.
Secondly, Proper Compressibility: Particles of powder or granules of the tablet should have proper compressibility. Compressibility is required for the proper compress of tablets.
A binder can accumulate fine particles to large particles (granules) and these large particles have adequate flow properties and compressibility. Certainly, during compression particles need to compact and this is possible when one or more binders used in a formulation. Thus, a binder is added either dry or in liquid form during wet granulation to form granules or to promote cohesive compacts for directly compressed tablets. In addition, the binder ensures the tablet shape remains unbroken after compression.
List of Tablet Binder used in Pharmaceutical Preparations [2]
| Name of Tablet Binder | Concentration (%) |
| Acacia | 1.0 – 5.0 |
| Copovidone | 2.0 – 5.0 (In direct compression)
2.0 – 5.0 (In wet granulation) |
| Carbomer | 0.75 – 3.0 |
| Corn Starch and Pregelatinized Starch | Commercially known as STARCH 1500 |
| Calcium carboxymethylcellulose; calcium cellulose glycolate; carmellosum calcium; | 5.0–15.0 |
| Carboxymethylcellulose Sodium, Carmellose Sodium | 1.0–6.0 |
| Ceratonia | 0.15 – 0.75 [3] |
| Chitosan Hydrochloride | Chitosan is a well-known polysaccharide |
| Dextrates | Purified mixture of saccharides |
| Dextrin | Low-molecular-weight carbohydrates |
| Ethylcellulose | Ethylcellulose being blended dry or wet granulated with a solvent such as ethanol (95%). |
| Liquid Glucose | 5.0 – 10.0 |
| Guar Galactomannan,/ Guar Gum | Up to 10.0 |
| Hydroxyethyl Cellulose | Derived from cellulose |
| Hydroxyethylmethyl Cellulose | Derived from cellulose |
| Hydroxypropyl Cellulose | 2.0 – 6.0 |
| Low-Substituted Hydroxypropyl Cellulose | Most widely used |
| Hydroxypropyl Starch | modified starch |
| Hypromellose/ hydroxypropyl methylcellulose (HPMC) , Methocel | Concentrations between 2% and
5% w/w may be used as a binder |
| Inulin | Naturally occurring polysaccharides |
| Magnesium Aluminum Silicate | 2.0 – 10.0 |
| Maltodextrin | 2–40 (direct compression)
3–10 (wet granulation) |
| Methylcellulose | 1.0–5.0 |
| PEG (Polyethylene Glycol) | Depending on MW (molecular weight) of PEG, it is also known as polyethylene oxide (PEO) or polyoxyethylene (POE). |
| Polyethylene Oxide | 5.0 – 85.0 |
| Povidone | 0.5 – 5.0 |
| Sodium Alginate | 1.0 – 3.0 |
| Starch | 3–20% w/w (usually 5–10%, depending on the starch type) as a binder for wet granulation |
| Pregelatinised Starch | 5-10% w/w |
| Sucrose | 2–20 (Dry granulation)
50–67 (Wet granulation) |
| Compressible Sugar | 5–20 as dry binder in tablet formulations |
| Zein | 30 (Wet granulation) |
| Gelatin | 1–3 Wet mix [4] |
| Polymethacrylates | 10–35 Dry mix [4]
15–35 as solution (4.5–10.5% w/w solids) |
| Sorbitol | 2–10 Wet mix [4] |
| Glucose | 2–25 Wet mix [4] |
| Sodium alginate | 1–3 Wet mix |
We know that the tablet is one of the most used and preferred dosage forms. Tablets are formed by using either
- Direct Compression
- Dry Granulation
- Wet Granulation
However, tablet binder is one of the most essential excipients for tablet manufacturing. They are used in the formulation of solid oral dosage forms to hold the API (active pharmaceutical ingredient) and excipients (inactive ingredients) together and to promote cohesive compacts for directly compressed tablets.
Ideal properties of a tablet binder
- Physiologically inert.
- Acceptable to regulatory agencies.
- Physiologically and chemically stable.
- Should not interfere with the bioavailability of the drug.
- Commercially available in a stable form.
- Meet the standards of regulatory requirements.
- Able to cohesive compacts for directly compressed tablets.
Also, You may read:
- Problems in Tablet Manufacturing.
- What is disintegrating agents or disintegrators or disintegrants?
- List of Sweetening agents used in Pharmaceutical Preparations.
References
- Lachman, Lieberman, H.A. and Kanig, J.L., The Theory and Practice of Industrial Pharmacy, Lea and Febiger, New York, 15th edition., 2013.
- Rowe, R. C., Sheskey, P. J., Owen, S. C., & American Pharmacists Association. (2006). Handbook of pharmaceutical excipients. London: Pharmaceutical Press.
- Gaud, R. S. (2008). Natural excipients. Pune, India: Nirali Prakashan.
- Cantor, Stu & Augsburger, Larry & Hoag, Stephen & Gerhardt, Armin. (2008). Pharmaceutical Granulation Processes, Mechanism and the Use of Binders.