Ointments defined

Pastes may be defined as a semisolid dosage form that contains a large proportion (i.e., 20-50%) of solids finely dispersed in a fatty vehicle (basically an ointment base) for external application to the skin. The presence of a high concentration of solids makes them much stiffer than ointments. Like ointments, pastes form an unbroken... 

The marine animal waxes are both solid and liquid. The solid marine animal waxes are represented by a wax of considerable economic importance, namely spermaceti, derived from a concrete obtained from the head of the sperm whale. The liquid waxes of marine animals arc represented by speim oil obtained from the blubbei and cavities in the head of the sperm whale. Spermaceti is the wax used in the candle which defines our unit of candle power it is used chiefly as a base for ointments, cerates, etc. Sperm oil contains a considerable amount of esters made up of unsaturated alcohols and acids, both of which are susceptible to hydrogenation. Hydrogenated sperm oil is the equivalent of spermaceti wax and harder than the commercial pressed spermaceti. Both yield cetyl alcohol as the unsaponifiable. There is a fairly large demand for cetyl alcohol in the manufacture of lipstick, shampoo, and other cosmetics. Sperm oil itself is an excellent lubricant for lubricating spindles of cotton and woolen mills, or wherever there is need for a very light, limpid, nongummmg lubricant. 

Oleum viride, strictivum oil obtained from olives changing colour when odoriferous substances were added the oil was defined oleum ad unguenta and used as ointment. 

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... 

These devices are similar to the microneedle devices produced by microfabrication technology. They include the use of needle-like structures or blades, which disrupt the skin barrier by creating holes and cuts as a result of a defined movement when in contact with the skin. Godshall and Anderson [101] described a method and apparatus for disruption of the epidermis in a reproducible manner. The apparatus consists of a plurality of microprotrusions of a length insufficient for penehation beyond the epidermis. The microprotrusions cut into the outer layers of the skin by movement of the device in a direction parallel to the skin surface. After disruption of the skin, passive (solution, patch, gel, ointment, etc.) or active (iontophoresis, electroporation, etc.) delivery methods can be used. Descriptions of other devices based on a similar mode of action have been described by Godshall [102], Kamen [103], Jang [104] and Lin et al. [105]. 

The exact product optimisation studies to be conducted will depend on the type of ophthalmic dosage form to be developed (liquid drops, semi-solid gel/ointment or solid device). However, the dosage form type should be clearly defined from the product design evaluation and supporting preformulation studies, to enable the formulator to focus on the most relevant product optimisation studies. 

In its strictest definitive form, an ointment is classified as any semi-solid containing fatty material and intended for external application (U.S. Pharmocopeia, USP). In this discussion, ointments will be defined as semisolid anhydrous external preparations. In the nineteenth century, ointments were based on lard, a compounding material, the usefulness of which was severely limited by its tendency to turn rancid. Early in the twentieth century, lard was replaced by petrolatum (white or yellow soft paraffin or petroleum jelly). In present practice, nonmedicated ointments (ointment bases) are used alone, for emollient or lubricating purposes, or in combination with a drug for therapeutic purposes. 

In the chemical industry (on the mega- as well as the micro-scale) fine emulsions have many useful applications in, e.g., extraction processes or phase transfer catalysis. Additionally, they are of interest for the pharmaceutical and cosmetic industry for the preparation of creams and ointments. Micromixers based on the principle of multilamination have been found to be particularly suitable for the generation of emulsions with narrow size distributions [33]. Haverkamp et al. showed the use of micromixers for the production of fine emulsions with well-defined droplet diameters for dermal applications [38]. Bayer et al. [39] reported on a study of silicon oil and water emulsion in micromixers and compared the results with those obtained in a stirred tank. They found similar droplet size distributions for both systems. However, the specific energy required to achieve a certain Sauter mean diameter was 3-1 Ox larger for the macrotool at diameters exceeding 100 pm. In addition, the micromixer was able to produce distributions with a mean as low as 3 pm, whereas the turbine stirrer ended up with around 30 pm. Based on energy considerations, the intensification factor for the microstirrer appears to be 3-10. 

Compatibility is defined here as good miscibility of the PEGs with various substances to form homogeneous mixtures that do not separate even when heated. This is a requirement, for instance, for ointments and other preparations. 

This work forms part of a larger programme to define those characteristics of the raw material drug substance that would enable rapid and effective dispersion in the ointment base. An ultimate objective is to be able to prepare these dispersions with an acceptable particle size without the need for prior micronisation. 

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