Ointments hydrocarbon

Several alternative means of forming hydrocarbon ointments illustrate their structural properties. Ointments can be made by incorporating high melting... 

The oleaginous phases of creams differ composi-tionally from hydrocarbon ointments. Many, but not all, creams are patterned after vanishing cream and contain considerable stearic acid. In lieu of some or all of the stearic acid, creams sometime contain long-chain waxy alcohols (cetyl, Ci6 stearyl, Ci8), long-chain esters (myristates, Ci4 palmitates, Ci6 stearates, Cig), other long-chain acids (palmatic acid), vegetable and animal oils, and assorted other waxes of both animal and mineral origin. 

The vast majority of ophthalmic ointments are essentially lipophilic and consist of mixtures of hydrocarbons. To improve spreading over the comeal surface and mixing with the precorneal him. small amount.s of lanolin and/or lanolin alcohols, impaning to the ointment base W/0 emulsifying properties, can be added. Suspension-type hydrocarbon ointments share with their "solution-type" homologs a poor patient acceptance, mostly due to their greasiness and vi.sion-blurring effect therefore, they are preferentially applied as nocturnal medications. 

If a material other than a hydrocarbon is used as the base material of an ointment-like system, the ointment bears the name of its principal ingredient. There are silicone ointments that contain polydimethylsiloxane oil in large proportion. These reportedly act as excellent water barriers and superior emollients. Some are actually used to protect skin from the undesirable effects of long immersion in water. 

Boric acid is used as an antiseptic in mouthwashes, eye washes, and ointments a preservative in natural products to protect wood against insect damage in washing citrus fruits as a catalyst in hydrocarbon oxidation as a flame retardant in cellulose insulation in nickel electroplating baths and as a buffer in ammonia analysis of wastewaters hy acid titration. 

Petrolatum is a purified material consisting of a complex combination of hydrocarbons with an ointment-like consistency and is derived from petroleum (crude oil). Based on its origin, it would seem that the properties of petrolatum would vary dramatically depending on the type of crude oil used. However, since different types of crude oils have widely differing properties (depending on the source of the oil), only certain waxy crudes are suitable for the manufacture of petrolatum. 

Eczema may be so mild that no treatment is required beyond avoiding known irritants and applying a soothing and protective ointment which keeps the skin moist and so reduces inflammation. There are many such over-the-counter remedies based on liquid paraffin and soft white paraffin, both of which are hydrocarbons obtained from refined petroleum and which contain nothing that can irritate the skin. Liquid paraffin is also called mineral oil and is available under a variety of trade names, such as Nujol, while soft white paraffin is better known as Vaseline. Emulsified mixtures of liquid paraffin and soft white paraffin make excellent skin creams. 

Bases are classified based on their composition and physical characteristics. The U.S. Pharmacopeia (USP) classifies ointment bases as hydrocarbon bases (oleaginous... 

Hydrocarbon bases are made of oleaginous materials. They provide emollient and protective properties and remain in the skin for prolonged periods. It is difficult to incorporate aqueous phases into hydrocarbon bases. However, powders can be incorporated into these bases with the aid of liquid petrolatum. Removal of hydrocarbon bases from the skin is difficult due to their oily nature. Petrolatum USP, white petrolatum USP, yellow ointment USP, and white ointment USP are examples of hydrocarbon bases. 

Water-removable bases are basically oil-in-water emulsions. Unlike hydrocarbon and absorption bases, a large proportion of aqueous phase can be incorporated into water-removable bases with the aid of suitable emulsifying agents. It is easy to remove these bases from the skin due to their hydrophilic nature. Hydrophilic ointment USP is an example of a water-removable ointment base. 

Water-removable ointments and creams are basically hydrophilic-type emulsions. They are prepared by fusion followed by mechanical addition approach. Hydrocarbon components are melted together and added to the aqueous phase that contains water-soluble components with constant stirring until the mixture congeals. A hydrophilic emulsifying agent is included in the aqueous phase in order to obtain stable oil-in-water dispersion. Sodium lauryl sulfate is used in the preparation of hydrophilic ointment USP. 

Ointments are commonly used for topical application of drugs to the eye.These vehicles are primarily mixtures of white petrolatum and liquid mineral oil with or without a water-miscible agent, such as lanolin.The mineral oil is added to the petrolatum to allow the vehicle to melt at body temperature, and the lanolin is added to the nonemulsive ointment base to absorb water. This allows for water and water-soluble drugs to be retained in the delivery system. Commercial ophthalmic ointments are derivatives of a hydrocarbon mixture of 60% petrolatum USP and 40% mineral oil USP, forming a molecular complex that is semisolid but melts at body temperature. In general, ointments are well tolerated by the ocular tissues, and when antibiotics are incorporated they are usually more stable in ointment than in solution. 

Ointments Hydrocarbon (oily), adsorptive water-washable, or water-soluble bases emulsifying agents, glycols, medicating agent External... 

Colloid mills are used to grind and disperse solids in hquids and to prepare emulsions. They operate on the principle of high-speed fluid shear to grind the feed material. Another application is in the manufacture of lubricating greases by dispersion of calcium stearate in hydrocarbon oils. In the paint industry, colloid mills are used to incorporate pigments in liquid vehicles. In the food industry, the mills are used to make purees, sauces, ointments, creams, lotions, and other products. 

Ointments are composed mostly of fluid hydrocarbons meshed in a mafrix of higher melting solid hydrocarbons. Common examples of ointment bases include mineral oil, petrolatum, and polyethylene glycol. Creams are semisolid emulsion systems with an opaque... 

Ointments utilize certain bases that act as vehicles to deliver the drug and to impart emollient and lubricant properties to the preparation. Usually, but not always, they contain medicinal substances. Properties of ointments may vary from product to product depending on their specific use, ease, and extent of application. In general, ointment bases may be classified into four general groups hydrocarbon, absorption, water-removable, and water-soluble bases. 

Mineral oil—a mixture of liquid hydrocarbons obtained from petroleum. These are useful as levigating agents to wet and incorporate solid substances (e.g., salicylic acid, zinc oxide) into the preparation of ointments that consist of oleaginous bases as their vehicle. There are two types of mineral oils listed in the US. Pharmacopeia/National Formulary (USP/NF). Mineral oil USP is also called heavy mineral oil with a specific gravity between 0.845 and 0.905 and a viscosity of not less 34.5 cSt (cSt = mm /s) at 40°C. Light mineral oil, NF has a specific gravity between 0.818 and 0.880 and a viscosity of not more than 33.5 cSt. Table 2 lists the commercially available mineral oil fractions. 

Pastes maybe defined as ointments incorporating a high percentage of insoluble particulate solids, sometimes as much as or more than 50%. The use of this high amount of insoluble particulate matter renders a stiffness to thesystem as a result of direct interactions between the dispersed particulates and by absorption of the liquid hydrocarbons from the vehicles onto the surface of the particles. Because of the stiffness, they remain in place after application and are used effectively to absorb serous secretions. Pastes as such are not suited for application to hairy parts of the body. Examples of insoluble ingredients serving as the dispersed phase include starch, zinc oxide, and calcium... 

Franks, A.J. Hydrocarbon bases for ointments and creams. Soap, Perfumes and Cosmetics 1964, 57, 221-319. 

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