Tablet Processing Elements of Tablet Press

1. Concept and characteristics of tablet press

Concept: Tablet press is a tablet preparation made by uniformly mixing drugs and excipients.

Features: ①Solid preparation ②High degree of institutionalization and automation of production ③Accurate dosage ④Can also meet different needs of clinical medical treatment or prevention

2. Types and quality requirements of tablet press

Types: ordinary tablet press, coated tablets, sugar-coated tablets, film-coated tablets, enteric-coated tablets, effervescent tablets, chewable tablets, multi-layer tablets, dispersible tablets, sublingual tablets, buccal tablets, implants, solution tablets, sustained-release tablets

Quality requirements: ①Moderate hardness; ②Uniform color and smooth appearance; ③Meet the requirements of weight difference and accurate content; ④Meet the requirements of disintegration or dissolution; ⑤Small doses of drugs or drugs with more intense effects should meet the requirements of content uniformity; ⑥Meet the requirements of relevant hygiene.

3. Common excipients for tablets are divided into the following four categories: fillers, binders, disintegrants, and lubricants.

(1) Fillers

The main function of fillers is to fill the weight or volume of tablets, so as to facilitate tablet compression. Common fillers include starch, sugar, cellulose and inorganic salts.

① Starch Corn starch is the most commonly used excipient for tablets. Starch has poor compressibility. If used alone, the pressed tablets will be too loose.
② Powdered sugar The advantage is that it has strong adhesion and can be used to increase the hardness of tablets. Its disadvantage is that it has strong hygroscopicity and is generally not used alone.
③ Dextrin
④ Lactose is an excellent tablet filler. It has good fluidity and compressibility and can be used for direct tablet compression of powder.
⑤ Compressible starch Also known as pregelatinized starch, it has good fluidity, compressibility, self-lubricity and dry adhesion, and has good disintegration effect.
⑥ Microcrystalline cellulose (MCC) has good compressibility and strong binding force, and can be used as a "dry adhesive" for direct tablet compression of powder.
⑦ Inorganic salts, such as calcium sulfate and calcium hydrogen phosphate, are often used in tablet excipients. However, it should be noted that calcium sulfate interferes with the absorption of certain main drugs (tetracycline drugs), so it is not suitable to use it at this time.
⑧ Mannitol is more suitable for preparing chewable tablets.

(2) Wetting agents and adhesives

Some drug powders are inherently sticky. Only by adding appropriate liquids can their inherent stickiness be induced. In this case, the added liquid is called a wetting agent; some drug powders are not sticky or have low stickiness. It is necessary to add sticky substances such as starch slurry to make them stick together. In this case, the added sticky substances are called adhesives.

① Distilled water Distilled water is a wetting agent. Since materials tend to absorb water quickly. If uneven wetting occurs, it is recommended to use low-concentration starch or ethanol instead.
② Ethanol Ethanol is also a wetting agent. It can be used for drugs that are easily decomposed when exposed to water, and can also be used for drugs that are too sticky when exposed to water. Generally, it is 30%~70%.
③ Starch slurry Starch slurry is a commonly used adhesive in tablets. There are two main methods for making starch slurry: boiling slurry and flushing slurry.
④ Sodium carboxymethyl cellulose (CMC-Na) Used as an adhesive, it is often used for drugs with poor compressibility.
⑤ Hydroxypropyl cellulose (HpC) It is used as an adhesive for wet granulation and can also be used as an adhesive for direct powder tableting.
⑥ Methyl cellulose and ethyl cellulose (MC; EC) Methyl cellulose has good water solubility and is used as an adhesive. Ethyl cellulose is insoluble in water. This property of ethyl cellulose is often used to use it in sustained and controlled release preparations (skeleton type or membrane controlled release type).
⑦ Hydroxypropyl methyl cellulose (HpMC) This is a commonly used film coating material.
⑧ Other adhesives Gelatin solution, sucrose solution, aqueous solution or alcohol solution of polyvinyl pyrrolidone (pVp).

(3) Disintegrants

Except for sustained (controlled) release tablets and tablets with certain special effects, disintegrants should be added to general tablets.

① Dry starch is a classic disintegrant, which is more suitable for tablets of water-insoluble or slightly soluble drugs, but has a poor disintegration effect on soluble drugs. This is because soluble drugs dissolve in water to produce a concentration difference, making it difficult for the water outside the tablet to penetrate into the inside of the tablet through the solution layer, hindering the water absorption and swelling of the starch inside the tablet. In production, external addition, internal addition or "internal and external addition" are generally used to achieve the expected disintegration effect.
② Sodium carboxymethyl starch (CMS-Na) has a very significant water absorption and swelling effect and is a disintegrant with excellent performance.
③ Low-substituted hydroxypropyl cellulose (L-HpC) It has a good water absorption rate and water absorption capacity.
④ Cross-linked polyvinyl pyrrolidone (also known as cross-linked pVp)
⑤ Cross-linked sodium carboxymethyl cellulose (CCNa) Swells with water.
⑥ Effervescent disintegrants

(4) Lubricants

Lubricants are a general term for glidants, anti-adhesive agents and (in a narrow sense) lubricants.

① Magnesium stearate Magnesium stearate is a hydrophobic lubricant. When used in excessive amounts, it will cause slow disintegration of tablets due to its hydrophobicity.
② Micro-powdered silica gel is a tablet glidant and can be used as a glidant for direct powder tableting.
③ Talc is mainly used as a glidant.
④ Hydrogenated vegetable oil is a lubricant with good lubricating properties.
⑤ Polyethylene glycol and magnesium lauryl sulfate are typical representatives of water-soluble lubricants. The former mainly uses polyethylene glycol 4000 and 6000, while the latter is a water-soluble lubricant.