Gel Methylcellulosi – Methylcellulose GelDear Colleagues, this week we will examine Methylcellulose gel, which is a vehicle with hydrophilic gel properties.
If we recall, gels, defined as the solid or semi-solid phase of a jelly or colloidal solution, are suspensions in an aqueous medium of an undissolved hydrated drug whose particle size approaches or reaches colloidal dimensions. Gels are dispersed systems formed from a liquid and a solid substance. However, this solid substance must be lyophilic and must not show solvation. In their preparation, natural (tragacanth gum, pectin, agar), synthetic, or semi-synthetic gums (methylcellulose, carboxymethylcellulose, carbopol) are used. Specific types are available for dermatological, ophthalmic, dental, and vaginal use. Gels dry quickly. To prevent this, glycerin, sorbitol, or propylene glycol is added. In addition, precautions must be taken against bacterial growth.Rp.
Methylcellulosum 1000 cps 4.0 g
Glycerolum 20.0 g
Benzalkonium chloride 0.1 g
Aqua 75.9 g
Ingredients in the formula;
Methylcellulose- Cellulose methyl ether- Methylcellulose- Methyl ether cellulose- Cologel;It is attached to the OH group of cellulose as a methyl ether. Methylcellulose is an excipient frequently used in oral and topical pharmaceutical preparations. Methylcellulose is a long-chain substituted cellulose derivative. It occurs as a white or yellowish-white, hygroscopic, odorless, fibrous, granular or powder form. It is practically insoluble in hot water, dehydrated alcohol, acetone, chloroform, ether, and toluene; it dissolves in cold water forming a colloidal dispersion. It is also soluble in glacial acetic acid and in a mixture of equal volumes of alcohol and chloroform. The pH of a 1% aqueous solution is between 5.5 and 8.0. Methylcellulose solutions are stable at room temperature between pH 3 and 11. However, below pH 3, its viscosity decreases. When its solutions are heated, the viscosity decreases upon gelation. Methylcellulose has been reported to exhibit incompatibilities with chlorocresol, mercuric chloride, resorcinol, tannic acid, silver nitrate, cetylpyridinium chloride, para-aminobenzoic acid, hydroxybenzoates, and phenol. The addition of large amounts of electrolytes to methylcellulose solutions increases the viscosity of the methylcellulose mucilage. However, at very high concentrations of added electrolytes, methylcellulose may precipitate completely. In large amounts, it causes eye and skin irritation.Glycerol- Glycerine- Glycerol- 85%;It is used for its solvent, vehicle, preservative, and viscosity-increasing properties. It is an important humectant agent. Glycerin is a clear, colorless or very pale-colored, hygroscopic, syrupy, odorless or almost odorless liquid with a sweet taste. It is miscible with water and alcohol; slightly soluble in acetone; practically insoluble in chloroform, ether, fixed oils, and essential oils. Aqueous solutions are neutral to litmus. According to the United States Pharmacopeia (USP), the pH of Glycerin Oral Solution, USP is between 5.5 and 7.5. Strong oxidizing agents form explosive mixtures with glycerin.Benzalkonium chloride- Zephiran chloride- Zilkonium chloride;Benzalkonium chloride is actually a mixture of alkylbenzyldimethylammonium chlorides. It is found as a white or yellowish-white powder, viscous gel, or gelatinous flakes. It is hygroscopic, with a mild aromatic odor and a very bitter taste. It is highly soluble in water and alcohol; its anhydrous form is soluble 1:100 in ether. Its aqueous solution is generally slightly alkaline and foams when shaken. It is incompatible with soaps and other anionic surfactants, citrates, iodides, nitrates, permanganates, salicylates, silver salts, and tartrates. It shows incompatibility with the contents of certain commercial rubber mixtures or plastics. Incompatibilities have been reported with aluminum, cotton fabrics, fluorescein sodium, hydrogen peroxide, kaolin, hydrous lanolin, and certain sulfonamides. Benzalkonium chloride is a quaternary ammonium antiseptic. It is used in pharmaceutical preparations as an antimicrobial preservative, solubilizing agent, and wetting agent. In ophthalmic preparations, it is present in concentrations of 0.01-0.02% (w/v). It is not a suitable preservative for eye drops as it exacerbates the dry-eye-inducing effects of local anesthetics. It is not suitable for inclusion as a preservative in solutions used for rinsing and storing hydrophilic soft contact lenses. It exhibits maximum stability at pH 5-6. It is used at a concentration of 0.01%.Principal action and uses;Besides being used as a hydrophilic gel for ointments, active substances can be added to this prepared gel for various purposes, such as the following compounds:
Hexachlorophene at 0.5-1% for antiseptic purposes,
Ichthammol up to 6% against eczema,
Pix lithanthracis up to 6% against eczema,
Precipitated sulfur at 5-10% for antiseptic and antiseborrheic purposes (sifted beforehand through a No. 180 sieve).Modus operandi (Preparation);Methylcellulose is mixed with glycerol. Benzalkonium chloride is dissolved in distilled water by heating. The methylcellulose-glycerol mixture is added to this mixture and cooled by stirring occasionally. It is kept in the refrigerator for 12 hours (40°C). Evaporated water is made up to weight.
Wishing you a pleasant week…
Spec. Pharm. Ahmet Nezihi Pekcan
Pekcan Pharmacy – Konya
[email protected]
Tel: (332) 3520657http://www.majistralformul.com/
