The polymer consists of glucose and has a molecular weight of up to 150. Dextran solutions are colorless and odorless substances of ointment-like consistency with high indifference and a pH of 4.5 to 6.5. Starch gels. Starch-glycerin gel is used, which is a colorless transparent homogeneous mass. It is easily distributed on the surface of the mucous membrane. Due to the presence of glycerin, this gel is resistant to microorganisms, but during storage is subject to syneresis – spontaneous reduction in the volume of the gel, accompanied by the separation of liquid. Starch-glycerin gel is excluded from the State Register, but is used in pharmacy practice.
Solutions and gels of natural and synthetic polymers represent a large group of water-soluble ointment bases. Polyethylene glycol bases have found the widest application among polymers of this group, they are included in pharmacopoeias of most countries of the world. Polyethylene glycol bases for ointments can be: separate monomers obtained by polymerization of ethylene oxide and having elastically viscous plastic consistency; a mixture of liquid and solid monomers, sometimes with the addition of any fillers.
In addition, polyethylene glycols (PEGs), also called polyethylene oxides (PEOs), can be used to prepare absorption, emulsion and other bases.
Polyethylene oxides are the product of polymerization of ethylene oxide in the presence of alkali. There are differentiated volatile (PEO-400) and solid (PEO-1500, PEO-4000) polyethylene oxides. Their consistency depends on the degree of polymerization. PEO-400 and PEO-1500 alloys are used as bases for ointments. Optimal rheological properties have an alloy in the ratio of 8:12. These bases are indifferent, resistant to heat and light, do not disrupt the physiological functions of the skin, easily release drugs and ensure their high bioavailability. They have high osmotic activity and are used in ointments for the treatment of purulent wounds (levomikol, levosin, etc.). In addition, polyethylene oxides can be used for the preparation of absorbent, emulsion and other bases. The disadvantage of polyethylene oxides is that they cause dehydration of mucous membranes.

Solutions of oligoesters. Oligoesters are esters of polyatomic alcohols (glycerol, sorbitol, diethylene glycol, etc.) and multibasic acids (tartaric, citric, succinic, etc.). Depending on the ratio of the initial components and the degree of their condensation, products of different viscosity can be obtained: from liquid to very thick.
Polyvinylpyrrolidone gels. Polyvinylpyrolidone (PVP) is a colorless amorphous hygroscopic powder, soluble in water, glycerol and polyethylene oxides. Aqueous solutions of PVP change color during storage and are subject to microbial contamination. PVP is miscible with lanolin, simple and esters, castor oil, cellulose derivatives and silicone fluids. PVP gel at concentrations up to 20% is used to prepare bases. Polyvinyl alcohol gels. Polyvinyl alcohol (PVS) is a white or yellowish powder, insoluble in ethyl alcohol. PVA is soluble in water and glycerin when heated. Aqueous solutions of PtHS are characterized by high viscosity. For ointments 15 % PVA gel is used.
Rarely cross-linked acrylic polymers (RAP) are copolymers of acrylic acid with polyalkyl polyethers of polyatomic alcohols. Abroad they are called “Carbopols” or “Carbomers”. In USA they are produced under the brand name “Arespol” or “MARS-06”. RAPs form viscous transparent homogeneous gels with maximum viscosity in the pH range from 5 to 9. They easily release drug substances and provide their high bioavailability. RAPs are absorbed through the skin and provide a prolonged effect.
Phytosterol gels. They are formed due to the ability of phytosterol to swell strongly in water, apparently due to the formation of H-bonds. Phytosterol is soluble in many organic solvents, but at the same time is able to retain significant amounts of water (12 times the initial mass of phytosterol). A gel consisting of 12-15% phytosterol and 88-85% water has been proposed as a base for ointments.
It is a white or slightly yellowish mass, which is mixed with amidochlorous mercury, zinc oxide, sulfur, ichthyol and other substances. Phytosterol is obtained from coniferous wood. The main component is B-sterol.