Cream: Topical Preparation
Pharmaceutical preparations for the treatment of conditions such as rashes, skin irritation, stings, fungal infections, etc. are normally supplied in the form of a cream or ointment as this provides an effective means of delivering the active ingredient directly to the required area
Pharmaceutical Creams (topical preparation) are homogeneous, semi-solid or viscous preparations that possess a relatively fluid consistency and are intended for external application to the skin or certain mucous membranes for protective, therapeutic or prophylactic purposes especially where an occlusive effect is not necessary.
They are semisolids usually consisting of solutions or dispersions of one or more medicaments in suitable bases. They are formulated using hydrophilic or hydrophobic bases to provide preparations that are essentially miscible with the skin secretion.
Creams can be also used for administering drugs via the vaginal route.
Type of Creams
Difference between Cream & Ointment
Classification of Creams
The Creams can be classified on various basis
- According to function, e.g. cleansing, foundation, massage, etc
- According to characteristics properties, e.g. cold creams, vanishing creams, etc.
- According to the nature or type of emulsion
- o/w emulsion type cream
- Vanishing creams
- Foundation creams.
- w/o emulsion type creams
- Cleansing cream,
- Cleansing milk,
- Cleansing lotion
- Cold cream or moisturizing creams/Winter cream
- o/w emulsion type cream
- Others creams
- All-purpose cream and general creams.
- Night cream and massage creams.
- Skin protective cream
- Hand and body creams.
It is a W/O emulsion cream which when applied to skin, a cooling effect is produced due to slow evaporation of water present in the emulsion.
Cold cream are an O/W type of emulsion but after application on the skin, sufficient water evaporates to permit phase inversion to w/o emulsion.
Cleansing creams are used to remove facial makeup & to improve the healthy/good appearance of the skin. It is used frequently to remove grime, sebum & other secretion, dead cells and applied makeup.
Pepsin is added to cleansing cream to make the facial skin smooth.
Cleansing cream are three types
- Liquefying cleansing cream
- Emulsified creams of o/w type
- Emulsified creams of w/o type
Creams spread easily & seem to disappear rapidly when rubbed on the skin are termed as vanishing creams.
Vanishing creams are an o/w type of emulsions which when applied to the skin leave an almost invisible layer on it so-called vanishing creams.
Vanishing creams can be quickly washed off with water due to the presence of o/w emulsifiers
These are applied to the face to provide a smooth emollient base for the application of facial makeup.
Foundation creams act as skin protectives to prevent the damage caused by environmental factors like sun, wind, dirt, etc.
Mostly O/W type emulsion
These creams are designed to be left on the skin. An occlusive layer of these creams slows the rate of transepidermal water loss, thus having a moisturizing effect & hence prevent the dry condition of the skin.
The base for Cream should:
- not produce irritation or sensitization of the skin,
- not retard wound healing;
- smooth, inert, odorless or almost odourless,
- physically and chemically stable and compatible with the skin and with incorporated medicaments.
Antimicrobial preservatives in creams
Creams may contain suitable antimicrobial preservatives unless the active ingredients or the bases themselves have sufficient bactericidal or fungicidal activity. They may contain other suitable auxiliary substances such as antioxidants, stabilizers, thickeners and emulsifiers.
Formulation of Creams
Pharmaceutical Cream can be either water in oil (w/o) or oil in water (o/w) emulsion, consisting of waxes, emollients and lubricants dispersed in an oil phase, and a water phase containing emulsifying, stabilizing and thickening agents, preservatives and in some cases, colorant. Active ingredients are dispersed in either phase or added when the emulsion has been formed and allowed to cool.
A typical manufacturing process breaks down into four individual operations
- Preparation of the oil phase:- Flake/powder ingredients, sometimes dry blended in advance, are dispersed into mineral oil or silicone oil. Heating may be required to melt some ingredients.
- Hydration of aqueous phase ingredients:- Emulsifiers, thickeners and stabilizers are dispersed into water in a separate vessel. Heating may be required to accelerate hydration.
- Forming the Emulsion:-The two phases are blended under vigorous agitation to form the emulsion.
- Dispersion of the Active Ingredient:-The active ingredient often makes up only a small proportion of the formulation; this must be efficiently dispersed to maximize yield and product effectiveness.
Using conventional agitators a number of problems can be encountered:
- When added to water, thickening, stabilizing and emulsifying ingredients can form agglomerates which agitators cannot break down.
- Similarly, oil phase ingredients can form lumps which require shear to disperse.
- Ingredients must be fully hydrated to obtain the required viscosity and develop yield.
- Partially hydrated materials can build up on the vessel wall, in-tank baffles and parts of the agitator.
- Agitators cannot sufficiently reduce droplet size to form a stable emulsion.
- Active ingredients can be temperature sensitive. Cooling of the product before adding the active ingredient further increases processing time.
- Poor dispersion of the active ingredient impairs product effectiveness.
- Long mixing times and additional equipment may be required to obtain a homogeneous and stable finished product
- Overcome of these problem by using Silverson mixer.
- A Silverson mixer can rapidly disperse solids into liquids, hydrate thickening and stabilizing agents, break down agglomerates, and finely reduce particle and globule size to form stable emulsions and suspensions
Packaing & Labelling of Creams
- Creams should be packed in well-closed containers fitted with closures that minimize contamination with micro-organisms
- Creams should be packed in collapsible tubes of suitable metal or plastic.
- The cream is sterile, where necessary;
- The name and concentration of any added antimicrobial preservative
- The storage conditions.
- Storage. Store at temperatures below 25″ unless otherwise directed. Do not freeze.
Test For Evaluation of Cream
- Uniformity of weight
- Sterility (For Sterile cream)
- Irritancy study
- Determination of pH
- Physical appearance
- Saponification value & Acid value (If oily base is used)
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