[Effect of the medium composition on the properties of gels based on sodium carboxymethylcellulose]

Sodium carboxymethylcellulose is a hydrogel substrate used in the Drug Formulation Technology to produce skin dressings, dental gels and the ophthalmic drugs.

To study the hydrophilic medium composition based on the sodium carboxymethylcellulose and excipients on the properties of hydrogels with 1% hydrocortisone.

Sodium carboxymethylcellulose, hydrocortisone, Tween 20, Ethanol 760 g/l, propylene glycol-1,2, N,N-dimethylacetamide, aqua purificata P Ph 9th. The dynamic viscosity were determined by the method described in a previous publication [9]. The test of the consistence: the hardness and cohesiveness of the hydrogels were tested by TPA test. Hydrocortisone release experiment was performed according to PPh 9th by the paddle apparatus. The amount of drug was determined by spectrophotometry method.

Hydrogel dressings show thixotropic properties, they are non-Newtonian fluids. The addition of increasing amounts of excipients reduces the shear stress. Compared to the control formulations, tested hydrogels are more cohesive, have a lower hardness with addition of 1% of Ethanol, Tween 20 and higher in other cases. Pharmaceutical availability of hydrocortisone follows the first order kinetics. Excipients added to the gels are speeding up the process in the presence of DMA, but are extending process with propylene glycol-1,2, Ethanol and Tween 20.

Tested hydrogels in the presence of Ethanol, GP-1,2, DMA, Tween 20 exhibit higher shear stress than the control formulations. Hydrogels based on the Na-carboxymethylcellulose are less hard and more cohesive. The drug release follows the first order kinetics.