Paraffin based ointment

Atkinson TW, Greenway MJ, Holland SJ, Merrifield DR, Scott HP. The use of laser diffraction particle size analysis to predict the dispersibility of a medicament in a paraffin based ointment. Spec Publ R Soc Chem 1992 102 139-152. 

The Use of Laser Diffraction Particle Size Analysis to Predict the Dispersibility of a Medicament in a Paraffin Based Ointment... 

It is important that the particle size analysis accurately reflects the actual size of particles and aggregates in the final product. Various physical characterisation methods were used to study the effects of modifying the precipitation conditions used in the preparation of the drug. In particular, analysis of suspensions in liquid paraffin by laser diffraction is described. This is considered to have especial value in predicting the dispersibility of the active in paraffin based ointments. 

The particle size of the drug substance was reduced using a hammer mill (Apex 314S) operating with hammers forward at 7980 rpm.,passing the material through a 0.027 screen. Samples of this material were taken for particle size analysis and other physical and chemical characterisation tests. The milled material was incorporated into paraffin based ointments. 

A suitable negative product control for an aqueous product could be distilled water in a similar container. A negative product control for testing an ointment could be a container of liquid paraffin or ointment base that has been sterilized by dry heat pouring the liquid paraffin from a container would be adequate to simulate squeezing of ointment from a tube. 

Benzylpenicillin is incompatible with rubber products and metal ions. Stability is affected by alcohols, surfactants, oxidizing and reducing agents, macrogols and other hydroxy compounds, glycerol, glycols, some paraffins and ointment bases, preservatives such as chlorocresol or thiomersal, blood and blood products, and antibacterials such as amphotericin, cephalosporins, and vancomycin. Injections of benzylpenicillins and aminoglycosides should be administered separately. 

The choice of an ointment base depends on the site of application. In the anterior part of the nose, where cilia are absent, and in rhinitis sicca or in atrophic rhinitis, a fatty ointment base is used. An example is Menthol-paraffin nasal ointment 0.6 % (Table 8.6). When the nasal mucosa does not function, as in atrophic rhinitis, possible ciliotoxicity of the... 

The active substance is dispersed in the ointment base. The first ointment t3q>e is applicable for only a few active substances dissolved in the non-aqueous ointment bases. To date, almost only paraffin-based lipophilic ointments are used for semisolid ophthalmic products. An example of this type of preparation is eye ointment with 0.5 % erythromycin (Table 10.13). Suitable triglyceride-based vehicles may lead to more solution-type eye ointments (see Sect. 10.7.3). 

Ointments were prepared from the powders and tested against pharmacopoeial standards. A major requirement of this characterisation was a knowledge of the particle size of the powder as first precipitated, after comminution, and as present once incorporated into the ointment base, or vehicle. Whilst various techniques could be used to determine the size distribution of the powder samples, it was considered that these would fail to account for any particle-vehicle interactions that were likely to occur in the paraffin based product. The size and dispersion quality of the drug substance in the ointment base may... 

Strong Ointment of Iodine, B.Vet.C. Prepared to contain 10 per cent of iodine and 7 5 per cent of potassium iodide in a wool fat and paraffin base. The total iodine content is determined by the method given under Chiniofon Sodium, using 1 g. 

Eye Ointment of Mercuric Oxide, B.P. Contains 1 0 per cent of yellow mercuric oxide in a paraffin base. 

Eye ointments are prepared in a semi-sohd base (e.g. Simple Eye Ointment BP, which consists of yellow soft paraffin, eight parts hqnid paraffin, one part wool fat, one part). The base is filtered when molten to remove particles and sterilized at 160°C for 2 hours. The drug is incorporated prior to sterilization if heat stable, or added aseptically to the sterile base. Finally, the prodnct is aseptically packed in clear sterile alumirtinm or plastic tnbes. Since the prodnct contains virtnally no water, the danger of bacteria proliferating in the ointment is neghgible. Therefore, there is no recommended maximum period during which they can be nsed. 

Simone and Popino have considered the stability of neomycin in both hydrophobic and hydrophilic ointment bases. No loss of potency over a period of 1 year at 20°C was reported for formulations containing carboxymethylcellulose, polyethylene glycol(P.E.G.) or white-soft paraffin. However, formulations containing hydrous lanolin were reported to be unstable. All materials used in the formulations were obtained from U.S. sources. Coates et al3°l investigated the use of P.E.G. from British sources and described neomycin as being incompatible with the materials tested. 

Ointments and Creams Ointments are applied to the skin for topical treatment or to be absorbed into the blood system for delivery to target areas. They are semisofid preparations obtained by mixing the API with selected ointment bases depending on intended use. These bases include petrolatum, paraffin, mineral oil, lanolin, and glycols. Preservatives are often added to ensure the ointments will maintain the recommended shelf life. 

Lipophilic ointment (oil ointment) consists of a lipophilic base (paraffin oil, petroleum jelly, wool fat [lanolin]) and may contain up to 10 % powder materials, such as zinc oxide, titanium oxide, starch, or a mixture of these. Emulsifying ointments are made of paraffins and an emulsifying wax, and are miscible with water. 

Ointments are similar to creams but may be more viscous. Many ointments are prepared from a base of anhydrous lanolin or white petrolatum, which is a mixture ofn-, iso-, and cyclic-paraffins. Waxes may be added to make the ointments harder. 

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. 

White soft paraffin and yellow soft paraffin are mixtures of semi-solid hydrocarbons. They are used as bases for ointments, as emollients in skin diseases, and as lubricants in treating dry eyes. Soft paraffin is also known as petroleum jelly, petrolatum, and Vaseline. 

Adams U, Neuwald E Comparative studies of the release of salicylic acid from medium-chain triglyceride gel and paraffin ointment bases in vitro and in vivo. Pharm Ind 1982 44 625— 629. 

Viscosity (dynamic) the rheological properties of petrolatum are determined by the ratio of the unbranched chains to the branched chains and cyclic components of the mixture. Petrolatum contains relatively high amounts of branched and cyclic hydrocarbons, in contrast to paraffin, which accounts for its softer character and makes it an ideal ointment base. ... 

Anionic emulsifying wax (3-30%) may also be mixed with soft and liquid paraffins to prepare anhydrous ointment bases such as emulsifying ointment BP. A preparation of 80% anionic emulsifying wax in white soft paraffin has been used as a soap substitute in the treatment of eczema. 

Ointments are generally composed of singlephase hydrophobic bases, such as pharmaceutical grades of soft paraffin or microcrystalline paraffin wax. 

Since 1969, bovine pancreatic DNase I has been used for the treatment of ulcers in dermatology [82-84]. It degrades the polynucleotides that are a main constituent of dead cells. One dermatological product based on DNase I is Elase . This ointment contains both bovine pancreatic DNase I as well as a fibrinolytic complex formulated in a mixture of polyethylene glycol and paraffin oil [85],... 

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. 

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