Liquid paraffin (Petrolatum Liquidum, U.S.P.; Liquid Petrolatum) consists chiefly of a mixture of hydrocarbons belonging to the methane series; it is obtained from petroleum by distilling off most of the lighter fractions, and purifying the liquid residue. Liquid paraffins are also known under the following trade-names:—Adepsine Oil, Alboline, Atoleine, Chrismaline, Glymol, Oleum Adepsinae Album, Oleum Deelinae (Yellow), Paroleine, Saxol, and Vaseline Oil (Yellow). It occurs as a colourless, oily, transparent, tasteless, non-fluorescent liquid, odourless when cold, but having a faint petroleum odour when heated. The B.P. specific gravity is given as 0.885 to 0.890 (U.S.P., 0.870 to 0.940 at 25°), but it is more generally found in commerce about 0.875, or even somewhat lower. Boiling-point, not below 360°. When heated on platinum foil it is completely volatilised, and should not give off acrid vapours.
Insoluble in water or alcohol; soluble in boiling absolute alcohol, very soluble in ether, chloroform, carbon disulphide, amyl alcohol, benzene, petroleum benzine, oil of turpentine, the fixed and volatile oils.
Dissolves bromine, iodine, iodoform, phosphorus; alkaloids and their salts are only slightly dissolved by it, but the addition of oleic acid materially increases the solubility.
Action and Uses.—Liquid paraffin is bland and non-irritant when applied to mucous surfaces. It is largely employed as a vehicle for oily spray solutions containing menthol, thymol, and the volatile. oils. For the preparation of solutions of' the alkaloids, almond oil is better, or almond oil, 1 part, may be mixed with liquid paraffin, 2 parts. The commercial varieties of liquid paraffin having a specific gravity rather lower than the B.P. standard, are preferred for use in sprays, as, hem,- less viscous, they are more readily broken up by the spray apparatus into the necessary fine particles for projection into the air passages. It is a suitable vehicle in which to suspend insoluble salts, such as calomel, mercury salicylate, etc., for hypodermic injection. Liquid paraffin is used as an emollient to the skin in irritable conditions, and to remove desquamative crusts; it is erroneously regarded as a nutritive application for the hair, and forms the basis of many brilliantines. It is used with oil immersion lenses in place of cedar wood oil. Liquid paraffin is administered internally as a substitute, for cod-liver oil, in phthisis and other conditions of malnutrition (see Emulsio Petrolei cum Hypophosphitibus). It is incapable of saponification, but may be emulsified and absorbed through the intestinal wall without actually becoming incorporated with the tissues. It acts as a lubricant during excretion, and has been found of service in colitis, chronic constipation, and other intestinal disorders, for which doses of 15 mils (4 fluid drachms) or more may be given. It is not a food, and cannot, therefore, act as a substitute for cod-liver oil, but it may assist the absorption of saponifiable fats. Liquid paraffin can be sterilised by heating it for half an hour at 120° to 140°, in small flasks or bottles, the necks of which are tightly plugged with cotton wool.
Dose.—2 to 8 mils (½ to 2 fluid drachms).
- Emulsio Petrolei cum Glycerophosphatibus, B.P.C.—EMULSION OF PETROLEUM WITH GLYCEROPHOSPHATES.
- This preparation contains 30 per cent. of liquid paraffin, with the glycerophosphates of calcium, magnesium, iron, potassium, and sodium, together with flavouring agents. It is used for the same purposes as Emulsio Petrolei cum Hypophosphitibus. Dose.—4 to 15 mils (1 to 4 fluid drachms).
- Emulsio Petrolei cum Hypophosphitibus, B.P.C.—EMULSION OF PETROLEUM WITH HYPOPHOSPHITES.
- This preparation contains 30 per cent. of liquid paraffin with the hypo. phosphites of calcium and sodium, together with flavouring agents. It is used in phthisis, where cod-liver oil disagrees. Doubt has, however, been expressed as to whether liquid paraffin is absorbed, and the hypophosphites being excreted as such, their action does not differ from that of other inorganic salts. Dose.—4 to 15 mils (1 to 4 fluid drachms).
- Parenol Liquidum, B.P.C.—LIQUID PARENOL. 7 in 10.
- A neutral liniment, which is readily absorbed by the skin. It possesses properties similar to those of solid parenol, and will be found especially useful in the treatment of skin diseases, for lubricating catheters, on as a vehicle for injections.
- Parogenum. B.P.C.—PAROGEN. Syn.—LIQUID PAROGEN; VASOLIMENT; OXYGENATED PARAFFIN.
- Liquid paraffin, 40; oleic acid, 40; ammoniated alcohol (5 per cent.), 20. Parogen is readily absorbed by the skin, and forms a useful vehicle for medicaments, when it is desired that their action shall not be merely superficial; parenol or liquid parenol may, however, sometimes be found preferable.
- Parogenum Spissum, B.P.C.—THICK PAROGEN. Syn.—Thick Vasoliment.
- Liquid paraffin, 48; hard paraffin, 12; oleic acid, 30; ammoniated alcohol (10 per cent.), 10. Thick parogen may be used as all ointment basis when absorption of a drug by the skin is required, but the use of parenol may sometimes be found preferable.