Topical formulations, solvents water

Betnovate scalp application is an aqueous suspension and contains carbomer, isopropyl alcohol, sodium hydroxide and purified water. Carbomer is a thickening agent and it is used to increase the stability of suspension/emulsion formulations. Isopropyl alcohol is often used in topical formulations. It may be used as a solvent or as a disinfectant (if >70% concentration). Sodium hydroxide would be used to adjust the pH of the formulation, specifically in this case... 

Hydroxyethylcellulose (HEC) (Nalrosol, Hercules) 135-140 °C T — 70S Ctccnposmoi Soluble in hot or cold water Insoluble in organic solvents Viscosity = 2-20,0(X) MPa for 2% aqueous solution. Ophthalmic formulations Topical formulations Thickener Stabiliser Water binder... 

Quick-breaking foams consist of a miscible solvent system such ethanol (qv) [64-17-5] and water, and a surfactant that is soluble in one of the solvents but not in both. These foams are advantageous for topical appHcation of pharmaceuticals because, once the foam hits the affected area, the foam coUapses, deUvering the product to the wound without further injury from mechanical dispersion. This method is especially usehil for treatment of bums. Some personal products such as nail poHsh remover and after-shave lotion have also been formulated as quick-breaking foams. 

Formulators can use the tendency of creams, gels, and other systems to evaporatively concentrate to advantage. Solvents are chosen and blended so that the drug remains soluble in the formed film long after application is made. This can be accomplished by replacing a fraction of the water or other highly volatile solvent found in these systems with solvents of far lower volatility. As previously pointed out, 5-15% propylene glycol is found in many topical corticosteroid creams and lotions just for this reason. 

Formulation additives used in topical drug or pesticide formulations can alter the stratum comeum barrier. Surfactants are least likely to be absorbed, but they can alter the lipid pathway by fluidization and delipidization of lipids, and proteins within the keratinocytes can become denatured. This is mostly likely associated with formulations containing anionic surfactants than non-ionic surfactants. Similar effects can be observed with solvents. Solvents can partition into the intercellular lipids, thereby changing membrane lipophilicity and barrier properties in the following order ether/acetone > DMSO > ethanol > water. Higher alcohols and oils do not damage the skin, but they can act as a depot for lipophilic drugs on the skin surface. The presence of water in several of these formulations can hydrate the skin. Skin occlusion with fabric or transdermal patches, creams, and ointments can increase epidermal hydration, which can increase permeability. 

Dimethyl ether may be used as an aerosol propellant for topical aerosol formulations in combination with hydrocarbons and other propellants. Generally, it cannot be used alone as a propellant owing to its high vapor pressure. Dimethyl ether is a good solvent and has the unique property of high water solubility, compared to other propellants. It has frequently been used with aqueous aerosols. A coarse, wet, spray is formed when dimethyl ether is used as a propellant. 

Mineral oil is used primarily as an excipient in topical pharmaceutical formulations, where its emollient properties are exploited as an ingredient in ointment bases see Table I. It is additionally used in oil-in-water emulsions,as a solvent, and as a lubricant in capsule and tablet formulations, and to a limited extent as a mold-release agent for cocoa butter suppositories. It has also been used in the preparation of microspheres. " ... 

Nitrogen and other compressed gases such as carbon dioxide and nitrous oxide are used as propellants for topical pharmaceutical aerosols. They are also used in other aerosol products that work satisfactorily with the coarse aerosol spray produced with compressed gases, e.g. furniture polish and window cleaner. Nitrogen is insoluble in water and other solvents, and therefore remains separated from the actual pharmaceutical formulation. 

In the case of dermal exposure, the contaminated area must be washed with plenty of water and soap. Topical application of vitamin E preparations may help to reduce the severity of skin reactions. The affected eye must be irrigated with lukewarm water for at least 10 min. The contaminated clothing is removed and the airway cleared. In the case of ingestion, gastric lavage is avoided as solvents present in cyfluthrin formulations may increase the risk of aspiration pneumonia. Atropine (adults and children >12 years 0.6-1.2mgkg children <12 years 0.02 mg kg by IV infusion) may be useful to... 

Formulations containing an absorption promoting substance, such as propylene glycol or sodium lauryl sulphate, may increase the permeability of the stratum comeum to water-soluble drugs. Propylene glycol is a commonly used vehicle in topical corticosteroid preparations for veterinary use. Various aprotic solvents, which include dimethylacetamide, dimethylformamide, dimethylsulphoxide, tetrahydrofurfuryl alcohol, and 2-pyrrolidone, serve as penetration enhancers of polar drugs (Barry, 1983). Dimethylsulphoxide... 

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