Technical Newsletter
Tablets are solid pharmaceutical forms with a specific shape, each containing an exact amount of one or more active ingredients, formed by compressing powder or granules with or without excipients on a tablet press. Tablets were first introduced in 1894 following the invention of the tablet press. With advances in tablet compression techniques and the development of biopharmaceutics, tablets have become increasingly popular and are now the most widely used dosage form, accounting for nearly two-thirds of the pharmaceuticals on the market. This popularity is primarily due to their suitability in formulation research, production, transportation, storage, and the convenience they offer to patients.
According to release characteristics, tablets are divided into two main groups:
In some cases of chronic diseases, patients need to maintain therapeutic drug levels in the blood for an extended period, making the prolonged use of immediate-release tablet formulations no longer suitable. In such instances, sustained-release formulations will be the preferred option.
APIs formulated as sustained-release tablets are often highly effective at low doses. The amount of API in sustained-release tablets is usually two to three times that of immediate-release tablets, aiming to maintain the therapeutic concentration over a long time and reduce the frequency of medication for patients. Therefore, the selection of appropriate excipients for this formulation is also very important, as it helps design tablets with a higher content of the active ingredient than immediate-release formulations while creating a structure that maintains the release of drugs, ensuring stable and safe blood concentrations for the patient.
Reservoir system: The active ingredient is contained within the tablet and is surrounded by a polymer membrane. Some polymers used for extended-release tablets include water-soluble polymers (PVA), water-insoluble polymers (EC), and pH-dependent polymers (aminoethyl methacrylate copolymer).
Matrix system: The active ingredient is distributed within a matrix formed by suitable excipients, then gradually dispersed in bodily fluids to achieve extended-release effects. The matrix-forming excipients are presented in the table below.
Matrix system | Excipients |
Hydrophobic, inert | Polyethylene, polyvinyl chloride, ethyl acrylate methacrylate copolymer, ethyl cellulose |
| Hydrophobic, erodible | Carnauba wax, stearyl alcohol, stearic acid, polyethylene glycol, polyethylene glycol monostearate, triglycerides |
Hydrophilic | Methylcellulose, hydroxyethyl cellulose, hydroxypropyl methylcellulose, sodium carboxy methyl cellulose, carboxy polymethylene, sodium alginate, galactomannan |
Applied to special dosage forms such as microencapsulation systems, congealing particles, spherical agglomeration particles, etc.
In general, sustained-release tablet formulations are a newly emerging dosage form that has gained attention recently due to numerous benefits in terms of therapeutic efficacy and patient medication adherence. However, the formulation and production of this dosage form face many challenges, requiring modern equipment, machinery, and technology. Sustained-release tablets can be considered a potential drug form and are currently receiving significant investment for development.
