Paraffin

• BPHard Paraffin
• JPParaffin
• Ph. Eur.Paraffin, Hard
• USP–NFParaffin

Hard paraffin; paraffin wax; hard wax; paraffinum solidum; petroleum wax

Purified mixture of solid saturated hydrocarbons obtained from petroleum · [8002-74-2]

CnH2n+2 (mainly n ≈ 20–40)

Semi-solid base, emollient

Typical concentrations: — · Dosage forms: Semi-solid

Used mainly in topical ointments and creams as a stiffening agent to raise the melting point and increase consistency, in combination with soft and liquid paraffins. It has also been used to coat capsules and tablets, as a sealing or moisture-barrier material, and in foods and confectionery.

A colourless or white, odourless, tasteless, translucent, wax-like solid that is slightly greasy to the touch and often shows a crystalline structure.

Congealing range

47–65 °C (USP–NF); about 50–61 °C (Ph. Eur. hard paraffin)

Density

about 0.84–0.89 g/cm³ at 20 °C

Solubility

practically insoluble in water and ethanol; soluble in chloroform, ether, volatile oils and most warm fixed oils

Acidity/alkalinity

neutral

Stable, although repeated melting and congealing can alter its physical properties. Store in a well-closed container at a temperature below about 40 °C.

Incompatible with strong oxidising agents.

Obtained from the wax-containing fractions of petroleum distillation by solvent dewaxing (crystallisation from solvents) or sweating, followed by refining such as hydrotreating or treatment with sulfuric acid and adsorbents.

Generally regarded as non-toxic and non-irritant in topical and oral use. Injection of paraffin has caused granulomatous reactions (paraffinomas), and inhalation of the fumes should be avoided.

Observe normal precautions for the quantity handled. Take care to avoid burns when working with the molten wax, and avoid overheating, which produces irritant fumes.

Permitted in the USA as a food additive under specified conditions (21 CFR 172.886, petroleum wax). Included in the FDA Inactive Ingredient Database (oral capsules and tablets; topical preparations) and in non-parenteral medicines licensed in Europe.

Liquid paraffin; white soft paraffin (petrolatum); microcrystalline wax; ceresin; white beeswax.

Paraffin forms large crystals and can make ointments brittle or prone to bleeding of oil on storage; microcrystalline wax is often blended in to give a smoother, more plastic texture.