Increasepharm first introduced the concept of niosomal gel, which was obtained by combining niosomes and gels for external use. For TCM and chemical medicine with good clinical effect but great toxic side effect and stimulation, making it into niosomal gel preparation so as to reduce the stimulation, toxic side effect and improve the therapeutic effect.
Microemulsion-based gel: Microemulsion is liquid solution composed of water, oil, and amphoteric molecules, with optical homogeneity and thermodynamic stability. In fact, microemulsion is a small nanoscale droplet with a particle size less than 100nm. It is composed of water phase, oil phase, surfactant and cosurfactant, among them, the surfactant and cosurfactant play a stabilizing role together. The formation of microemulsion does not need external work.
As a new drug delivery system, microemulsion has the advantages of good stability, strong solubility, low viscosity, simple preparation, easy industrialization, and sterilization by filtration. In recent years, microemulsion has been widely concerned in the field of pharmaceutics, which has been used in the study of transdermal, oral, injection, mucosal delivery and other routes of administration. Microemulsion is widely used in transdermal drug delivery system.
As a drug carrier, microemulsion has the following advantages: ⑴ Microemulsion is an isotropic transparent liquid with thermodynamic stability, which can be filtered and sterilized; ⑵ The drug in microemulsion has good dispersibility and rapid absorption, which can increase the solubility and bioavailability of the drug; ⑶ It has high drug loading, can contain hydrophilic drugs or lipophilic drugs, and protect unstable drugs by water-in-oil microemulsion; ⑷ Because micro-emulsion has surfactant in its composition, it has good permeability to skin and mucosa.
However, the micro-emulsion also has some problems such as inconvenient and not easy to apply. Therefore, we use microemulsion-based gel, which is obtained by combining microemulsion and gel, as the carrier of transdermal drug delivery system with good stability, can increase the solubility of lipophilic and hydrophilic drugs and the rate of penetration of drugs through skin, make the drug release at constant speed, avoid plasma concentration of drug achieving Cmax rapidly, and has long-term controlled release.
In situ gel In situ gel, also known as instant gel, is a kind of preparation which can immediately experience a phase transit after being administered in solution state and converted from liquid to non-chemically cross linked semisolid gel preparation.
Drugs and gel materials can be made into homogeneous, suspended latex thick liquid or semi-solid gel. The gel has good histocompatibility, and has a long retention time at the administration part. At the same time, it can play a role in storing drugs and preventing the drugs from being affected by the environment.
Depending on the forming mechanism, in situ gels can be classified into temperature-sensitive, pH-sensitive, and ion-sensitive. In situ gels are a new type of dosage form, which are widely used in new drug delivery systems such as sustained release, controlled release and pulsatile release. In situ gels can be applied to the skin, eyes, nasal cavity, mouth, vagina, rectum, etc. Today, in situ gel delivery system has become a research hotspot in the fields of pharmacy and biotechnology.
