Pharmaceutical Lotion

Lotions are usually liquid suspensions or dispersions intended for external application to the body. They may be prepared by:

(1) Triturating the ingredients to a smooth paste and then cautiously adding the remaining liquid phase or in larger quantities by the use of high-speed mixers or homogenizers. Classical example is the Calamine Lotion, which consists of finely powdered insoluble solids held in more or less permanent suspension by the presence of suspending agents and/or surface active agents.

(2) By chemical interaction in the liquid. Example – White Lotion which must be freshly prepared and does not contain a suspending agent. The second type of lotion recognized by the USP XVII is the O/W type stabilized by a surface active agent. Example of this is Benzyl Benzoate Lotion.

(3) Some Lotions are clear solutions and in fact, the active ingredients of one official lotion, Dimethisoqun Hydrochloride Lotion, is a water soluble substance.

Lotions are usually applied without friction. The insoluble matter should be finely divided as particles approaching colloidal dimensions are more soothing to inflamed areas and are more effective in contact with infected surfaces. A wide variety of ingredients may be added to the preparation to produce better dispersion or to accentuate the cooling, soothing, drying, or protective properties of the lotion. A good example of suspending agent is bentonite. Methylcellulose or sodium carboxymethylcellulose will localize and hold the active ingredient in contact with affected site. A formulation containing glycerin will keep the skin moist for a considerable period of time. Addition of alcohol to the formula will accentuate the drying and cooling effects.

Dermatologist frequently prescribe lotions containing anesthetics, antiseptic, astringents, germicides, protective or screening agents, to be used in treating and preventing various types of skin disease and dermatitis. Antihistamines, benzocaine, calamine, resorcin, steroids, sulfur, zinc oxide, and zirconium oxide are common ingredients in unofficial lotions.

Lotions tend to separate or stratify on long standing, so a “shake well” label is required for them. All lotions should be labeled “For External Use Only”.

Preparations of Lotions

Benzyl Benzoate Lotion, USP, BP

Other Names: Lotio Benzylis Benzoatis; Benzyl Benzoate Application.

Formula:

Benzyl Benzoate              250ml

Triethanolamine                  5g

Oleic Acid                          20g

Water                                750ml

          To make about      1000ml

Preparation:

Mix together the triethanolamine and oleic acid add the benzyl benzoate and mix well. Transfer the mixture to a suitable container of about 2000ml capacity, add 250ml of water and shake thoroughly. Add the remaining 500ml of water and shake again.

Uses: Scabicide. It is applied with a brush after the entire body has been thoroughly scrubbed with soft soap and hot water. A second coating is applied when the first is dry and the lotion is left on the body for 24 hours. Then the body is again bathe thoroughly and dressed in clean clothes.

Application: Adults require from 120 – 180ml. Children require from 60 – 90ml.

Caution: Do not apply to the face!

Calamine Lotion, USP

Other Name: Lotio Calaminae

Formula:

Calamine                                               80g

Zinc Oxide                                            80g

Glycerin                                               20ml

Bentonite Magma                                20ml

Calcium Hydroxide Solution q.s.     ________

                 To make                            1000ml

Preparation:

Dilute the bentonite magma with an equal volume of calcium hydroxide solution. Mix the powders intimately with the glycerin and about 100ml of the dilute magma, triturating until smooth, uniform paste is formed. Gradually incorporate the remainder of the diluted magma. Finally add enough calcium hydroxide solution to make 1000ml and shake well.

Uses: Astringent and protective.

Note: Shake lotions thoroughly before dispensing. If a more viscous consistency is desired, the quantity of bentonite magma may be increased to not more than 400ml.

Phenolated Calamine Lotion, USP

Other Names: Lotion Calaminae Phenolata; Lotion Calaminae Composita; Compound Calamine Lotion.

Formula:

Liquefied Phenol             10ml

Calamine Lotion             990ml

              To make           1000ml

Preparation:

Mix the ingredients thoroughly.

Uses: Astringent and protective for skin diseases. Shake well before using.

White Lotion, USP

Other Names: Lotio Alba; Lotio Sulfurata

Formula:

Zinc Sulfate                         40g

Sulfurated Potash                40g

Purified Water, q.s.       __________

           To make                 1000ml

Preparation:

Dissolve the zinc sulfate and the sulfurated potash separately, each in 450ml of purified water, and filter each solution. Add slowly the sulfurated potash solution to the zinc sulfate solution with constant stirring. Then add sufficient amount of purified water and mix.

Uses: Topically as astringent and protective.

Note: Lotion should be freshly prepared and shaken thoroughly before dispensing.

The lotion is a result of the chemical reaction between zinc sulfate and sulfurated potash and can be illustrated as follows:

 

ZnSO4       +      K2S3                            K2SO4           +         ZnS           +      2 S

Zinc Sulfate                Sulfurated Potash            Potassium Sulfate       Zinc Sulfate           Sulfur

The sulfurated potash solution should be added to zinc sulfate solution with constant stirring. This ensures a fine dispersion of the insoluble precipitates, upon long standing tends to become lumpy and yellowish in color.