Application of Hydroxy Propyl Methyl Cellulose in Eye Drops
HydroxyPropyl Methyl Cellulose solution with the maximum viscosity and clarity is very important for its application in eye drops.
Eye-drop preparations generally use many excipients, such as adjusting the pH value within the range of 5.0 to 9.0, adjusting the osmotic pressure in the isotonic range and adding antimicrobial agents to prevent microbial contamination. Some drugs even need to add solubilizers and stabilizers.
The pH value of 1% HydroxyPropyl Methyl Cellulose solution is 4-8 and the viscosity is stable in the pH range of 3.0 -11.0. In addition, it has optimum compatibility with the electrolyte, so suitable for use in the eye drops as thickening agents. The use at a concentration of 0.45% to 1.0% can extend the contact time with the eye, increase drug absorption, and improve bioavailability.
Hydroxypropyl methyl cellulose often acts as the suspending agent in suspension eye drops. It can increase the viscosity of the solvent, reduce the density difference between particles and the dispersion medium, and increase the hydrophilicity of particles. By the effect of gravity, suspended particles will naturally settle on standing, and the sedimentation rate is in accordance with Stokes law. The sedimentation rate is inversely proportional to the viscosity of the dispersion medium, but proportional to reducing the density difference between particles and the dispersion medium. In addition, HydroxyPropyl Methyl Cellulose can act as the gel matrix in gel-type eye ointments.