Petrolatum: Conditioning Through Occlusion
Randy Schueller, Perry Romanowski in Conditioning Agents for Hair and Skin, 2020
Generally, the most practical knowledge of the composition of petrolatum is based on the amounts of solid and liquid components in the material. The solid components are obviously mineral waxes (e.g., paraffin and microcrystalline wax), while the liquid component is a heavy mineral oil. [It should be noted, however, that even this border between the solid wax hydrocarbons and liquid mineral hydrocarbons "is neither definite nor scientific" (16). One can easily identify many saturated hydrocarbon molecules which melt at or near ambient temperatures.] The paraffin waxes are commonly recognized as paraffinic components, due to their brittleness. This lack of ductility arises from the ease by which the paraffinic molecules can align themselves and crystallize, due to the overall lack of significant branching. On the other hand, microcrystalline waxes are isoparaffinic, will not crystallize easily due to molecular branching, and so are not as brittle as the paraffin waxes.
Topical formulations
Karen Anne Gunnell, Rebecca Hayley Venables in A Practical Guide to Medicines Administration, 2018
Ointments are uniphase preparations within which solids or liquids are dispersed. Ointments are often firmer in consistency and greasier than creams, and thus tend to be less acceptable to patients for topical application. Some patients may prefer to reserve the use of ointments to night-time. They are particularly useful for dry skin, under wet wraps and when areas of skin have thickened, as they retain moisture well within the skin; this can promote repair of the skin barrier.1 Some ointments contain paraffin. If the content of paraffin within a preparation is greater than 50%, then the ointment can be flammable. Patients should be advised to avoid smoking and naked flames. They should also be advised to change clothing and bedding regularly, as the paraffin can soak into these and make them flammable.2
Routine and Special Techniques in Toxicologic Pathology
Pritam S. Sahota, James A. Popp, Jerry F. Hardisty, Chirukandath Gopinath, Page R. Bouchard in Toxicologic Pathology, 2018
After clearing, the tissue is infiltrated with paraffin. Infiltration is the complete removal of the clearing reagents, by substitution with paraffin. The tissue is placed in a paraffin bath, where liquid paraffin penetrates the tissue. The temperature of the paraffin bath is critical. The melting point of paraffin ranges from 47 to 64°C (Spencer and Bancroft 2013). Temperatures >5°C above the melting point will cause excessive shrinkage and hardening of tissue samples. During infiltration, the cassettes are exposed to a vacuum that removes air, gases, and any remaining clearing reagent and at the same time will aid in drawing paraffin into all areas of the tissue.
Effect of drug load and lipid–wax blends on drug release and stability from spray-congealed microparticles
Published in Pharmaceutical Development and Technology, 2022
Hongyi Ouyang, Soon Jun Ang, Zong Yang Lee, Tze Ning Hiew, Paul Wan Sia Heng, Lai Wah Chan
Hydrophobic carriers, in particular solid lipids, have been increasingly used to achieve taste-masking, modified-release, and increased stability of drugs. However, there are very limited studies on the use of paraffin wax in oral dosage forms, where it can potentially be used as a hydrophobic matrix material in spray congealing to modify drug release or enhance the stability of drugs. Conventionally, paraffin wax comprises a mixture of n-alkanes, iso-alkanes, and cyclo-alkanes that is obtained from crude oil through high-pressure hydrogenation. It is not commonly employed to develop pharmaceutical dosage forms due to reservations regarding its quality. More recently, pharmaceutical-grade paraffin wax (Ph. Eur/USP-NF) has become available as the Fischer–Tropsch (FT) process is utilized to yield hydrocarbon chains from syngas (Sasol 2022). After subsequent distillation and hydrogenation, paraffin wax of a particular chain length can be produced. One major advantage is that such paraffin wax has higher chemical purity, characterized by linear molecular chains and very low iso-alkane content. This would translate into consistent and predictable properties, ideal for use in pharmaceutical dosage forms. The advent of FT paraffin wax has potentially provided opportunities for its use in drug delivery systems and the interest in this wax for drug encapsulation by spray congealing. A previous study explored its ability to taste mask a bitter drug by exploiting the hydrophobic nature of the wax (Ouyang et al. 2018).
Polyphenol-Rich Fraction of Parquetina nigrescens Mitigates Dichlorvos-Induced Cardiorenal Dysfunction Through Reduction in Cardiac Nitrotyrosine and Renal p38 Expressions in Wistar Rats
Published in Journal of Dietary Supplements, 2018
Ademola A. Oyagbemi, Temidayo O. Omobowale, Grace O. Ochigbo, Ebunoluwa R. Asenuga, Olufunke Eunice Ola-Davies, Temitayo O. Ajibade, Adebowale B. Saba, Adeolu A. Adedapo
Immunohistochemistry of paraffin-embedded tissue of the heart and kidney was performed after the tissues were obtained from buffered formalin–perfused rats. The tissues were processed for immunohistochemistry following the methods described by Todorich et al. (2011). First, paraffin sections were melted at 60°C in the oven. Dewaxing of the samples in xylene was followed by passage through ethanol of decreasing concentration (100%–80%). Next, peroxidase quenching in 3% H2O2/methanol was carried out with subsequent antigen retrieval performed by microwave heating in 0.01 M citrate buffer (pH 6.0) to boil. All the sections were blocked in normal goat serum (10%, HistoMark, KPL, Gaithersburg MD, USA) and probed with nitrotyrosine antibody and p38 antibody (Abclonal), 1:375 for 16 h at room temperature. Detection of bound antibody was carried out using biotinylated (goat anti-rabbit, 2.0 µg/ml) secondary antibody and, subsequently, streptavidin peroxidase (horseradish peroxidase–streptavidin) according to manufacturer's protocol (HistoMark, KPL, Gaithersburg MD, USA).
Paeoniflorin improves autoimmune myocarditis in young rat by inhibiting CXCR5 to reduce follicular helper T cells
Published in Autoimmunity, 2022
Chunxiao Wang, Lanlan Wang, Li Wang
The myocardial tissues were soaked in 4% paraformaldehyde and fixed for 24 h, then dehydrated, embedded in paraffin, and sliced (about 4 µm thick). Placed the prepared paraffin sections in an oven at 65 °C for 2 h. The dried paraffin sections were dewaxed with xylene. The slices were immersed in ethanol with different concentration gradients for dewaxing. The dewaxed slices were immersed in the prepared hematoxylin solution (Solarbio, Beijing, China), dyed for 5 min, washed with ultrapure water to remove the floating liquid. Differentiation with 1% hydrochloric acid alcohol solution for 10 s, repeated washing with flowing ultrapure water, and cleaning with 6% ammonia for 5 min. Stained with 0.5% eosin ethanol solution (Solarbio, Beijing, China) for 1 min. Then, the stained sections were given 95% ethanol, soaked for 30 s, washed with flowing water, immersed in the concentration gradient of 75%, 90% and anhydrous alcohol for dehydration, transparent agent was soaked. Sealed, dried, and observed under an optical microscope (Leica, Germany). Under a 200× microscope, five visual fields were randomly photographed for each slice, and the inflammatory infiltration area was calculated by Image Pro Plus software (Media Cybernetics, USA). The score was calculated as a percentage of the area of inflammatory infiltration. Scoring criteria were as follows: 0: no inflammatory cell invasion; 1: < 5% inflammatory cell infiltration; 2: 5–*10% inflammatory cell infiltration; 3: 10–25% inflammatory cell infiltration; 4: >25% inflammatory cell infiltration.