Ointment hydrophobic

Heller, J., Ng, S.Y., Fritzinger, B.K., and Roskos, K.V. (1990) Controlled drug release from bioerodible hydrophobic ointments. Biomaterials, 11, 235-237. 

M. Masuda, S. Koike, M. Handa, K. Sagara, and T. Mizutani, Application of supercritical fluid extraction and chromatography to assay fat-soluble vitamins in hydrophobic ointment, Anal. Sci., 9 29 (1993). 

Stearyl Alcohol Reduction of ethyl stearate in the presence of lithium aluminum hydride yields stearyl alcohol, which contains not less than 90% of 1-octadecanol. It is available as flakes or granules which are white in color and possesses a characteristic odor. It is insoluble in water and melts at 55-60 °C. Stearyl alcohol has stiffening, viscosity-enhancing, and emollient properties and hence is used in the preparation of hydrophobic ointments and creams. Its weak emulsifying properties help in improving the water-holding capacity of ointments. Hypersensitivity reactions are sometimes observed due to the presence of some minor impurities. Stearyl alcohol preparations are compatible with acids and alkalis and are preserved in well-closed containers in a cool and dry place [6]. 

Water emulsifying and hydrophobic ointments containing boric acid liberate only small amounts within 24 h compared with a near total liberation from a... 

The application of SCF to the extraction of vitamins has been widely reported. Thus, retinyl palmitate and tocopherol acetate have been extracted from a hydrophobic ointment with supercritical CO2 at 40°C and 196 bar for 4 min, the extract analysis being performed by SFC (137). The calibration graphs were linear from 0.5 to 2.5 pg and the recoveries were quantitative. On the other hand, water-soluble vitamins can be extracted mixing them with low substituted hydroxypropil cellulose. Portions were placed in a column to which a reversed micellar extractant was delivered (138). Extraction of vitamins A and E and their esters from tablet preparations prior to FIPLC was performed in the dynamic mode with CO2 at 40°C and 253 bar for 15 min (139). Calibration graphs were linear from 0.02 to 0.8 and from 0.005 to 0.2 mg/mL of vitamins E and A, respectively. The corresponding RSDs (six... 

If a licensed product has to be adapted, the pharmacist should suggest a standard pharmacy preparation with a comparable base and chemical form of the active substance. For example the type of emulsion has to be the same or an anhydrous formulation such as a hydrophilic or hydrophobic ointment should be replaced with a similar anhydrous preparation. 

Ointments are cutaneous preparations consisting of one phase, hydrophilic or hydrophobic, in which a solid phase may be dispersed. They are subdivided in hydrophobic ointments, water-emulsifying ointments and hydrophilic ointments. 

Hydrophobic ointments are ointments that can absorb only small quantities of water. The base of water emulsifying ointments is similar to the base of the hydro-phobic ointments but also contains one or a few emulsifying agents, so they can absorb larger quantities of water than hydrophobic ointments and form water-in-oU (w/o) or oil-in-water (o/w) emulsions, depending on the type of the emulsifier. Hydrophilic ointments are ointments which consist of only a hydrophilic phase. They are miscible with water. 

Hydrophobic ointment Ointment Coal tar soft paraffin ointment (Table 12.25)... 

A slightly dry skin may be treated with an extra fat containing hydrophUic cream. Patients with a very dry skin use cutaneous preparatirms with a high amount of hpophUic components. Lipophilic creams are suitable for the treatment of the chronic state of atopic eczema. Hydrophobic ointments or saturated hydrocarbons are not indicated because they have an occlusive effect, which causes heat accumulation and enhances itching. 

A strong keratotic skin is treated with hydrophobic ointments. Hydrophobic anhydrous bases cover the skin and prevent evaporation of water, the skin becomes hydrated. Examples for such disorders are ichthyosis or psoriasis. 

Another approach is that for hydrophilic creams the amount should be limited to as much as the skin can absorb. Lipophilic creams and hydrophobic ointments should be applied in a thin layer until the skin feels slightly fatty. 

Hydrocarbons such as liquid paraffin and white soft paraffin are also called mineral oils. They hardly penetrate the skin and in cutaneous preparations they are mainly used for protection of the surface of the skin or occlusion. They absorb little or no water. Because they cover the skin they prevent evaporation of water and hydrate the skin. Hydrocarbcais are used in lipophilic creams, hydrophobic ointments and pastes. 

Hydrophobic ointments, frequently called fatty ointments, are plastic lipogels, in which active substances and excipients may be dissolved or dispersed. A hydrophobic ointment can absorb only a small quantity of water or water-miscible fluids. They are not washable. 

See Sect. 12.5.2. Suitable substances for hydrophobic ointments are white soft paraffin, liquid and solid paraffin, vegetable and animal fats and fatty oils, synthetic esters of glycerol or alcohols or mixtures of these substances. 

See Sect. 12.6.1.2. Hydrophobic ointments are usually prepared by melting all lipophilic ingredients and stirring the mixture while it is cooling down. The consistency of the product depends on the speed of the cooling down and the stirring speed. 

W/o emulsifying ointments consist of a lipophilic phase containing w/o emulsifiers. Because of these properties the water binding capacity is much higher than in hydrophobic ointments. 

The ingredients used in w/o emulsifying ointments are the same as in hydrophobic ointments, but a w/o surfactant is added such as ... 

Basically the preparatiOTi of w/o emulsifying ointments and the processing of active substances are similar to hydrophobic ointments. Whether heating is meaningful depends on the properties of the ingredients. Emulsifying Hydrophobic Base Gel (Table 12.26) for example is prepared by mixing all substances at room temperature. The Hydrophobic Base Gel does not tolerate temperatures above 70 °C. 

The preparation of sterile hydrophobic ointments is similar to that of eye ointments, see Sect. 10.7.3. The base however does not have to be filtrated until particle free. 

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