OINTMENTS

Ointments

Ointments are soft semi-solid preparations containing medicaments meant for external application to the skin or mucous membrane.

Ointments are semisolid dosage forms designed for topical application.

They consist of a drug or active ingredient dissolved, suspended, or dispersed in a suitable base.

Ointments are used to treat skin conditions, deliver medications, and provide moisture to the skin.

Types/classification of ointments:

Ointments can be classified based on their composition and use:

Medicated Ointments

These contain active pharmaceutical ingredients (APIs) for therapeutic purposes, such as antibiotic ointments for infection treatment.

Non-Medicated Ointments

These are used for cosmetic purposes or to provide a protective barrier, like moisturizing or emollient ointments.

Eye Ointments

Formulated for ophthalmic use, these are applied to the inner surface of the lower eyelid to treat eye conditions.

Nasal Ointments

These are applied within the nostrils for local effects, such as decongestants or antiseptics.

Rectal ointment

Ointment applied in the rectum

Ointment base

Ointment base is a soft semisolid vehicle in which medicaments is incorporated or dispersed or suspended.

Requirements of ideal ointment base:

1. The absorption and penetration should be high.

2. It is compatible with skin secretions.

3. It is miscible with skin secretions.

4. It should be compatible with many ingredients.

5. It should be smooth & pourable.

6. It should chemically stable & physiologically inert.

7. It should be non-toxic, non-irritant & non-sensitive.

8. It should be easily washable.

9. It should be non-staining.

10.  It should release the incorporated medicament readily.

Types of ointments bases:

 The ointment various bases are classified into

1. Oleaginous bases

2. Absorption bases

3. Emulsion bases

4. Water soluble bases

Oleaginous bases:

These consist of water insoluble hydrophobic oils & fats. They may contain a single hydrophobic substances or combination of two & more substances.

They are: Non-greasy, Anhydrous, Hydrophobic, Insoluble in water, Non-washable

               They do not release the medicament easily.

               They are very difficult to remove the skin.

Ex: Soft paraffin, Hard paraffin, Liquid paraffin, Castor oil, Coconut oil

Absorption bases:

They can absorb a large amount of water due to their high water number they are: Anhydrous, Hydrophilic (water can be incorporated)

Insoluble in water, Not water washable

  Ex: Wool fat, Wool alcohol, Cholesterol, Bees wax

Advantages:

            1. They are compatible with majority of medicament.

            2. They are heat stable.

            3. These bases may be used either in anhydrous form or in emulsified form.

            4. They can absorb a large quantity of water or aqueous substances.

Emulsion bases:

Emulsions bases are classified into

1. Oil in water type:

This type of ointment base is hydrous, hydrophilic, and insoluble in water & water washable. Ex: Emulsifying wax, Sodium lauryl sulphate.

2. Water in oil type:

This type of ointment base is hydrous, hydrophilic, and insoluble in water & not water washable. Ex: Wool alcohol, Wool fat and bees wax

3. Water soluble bases:

They are anhydrous, hydrophilic, and soluble in water & water washable.Ex: Poly ethylene glycol, Sodium carboxyl methyl cellulose, Glycerol mono-stearate.

Factors which govern the selection of an ideal base for ointments:

There are two factor:

I. Dermatological factors 

II. Pharmaceutical factors 

I) Dermatological factors:

1. Absorption & penetration: Absorption is systemic absorption & entry into the stream while penetration means passage through the skin.

Ex: Cutaneous absorption, Penetration of the ointment occurs through

      1. Hair follicle.

      2. Sebaceous glands.

      3. Non keratinized cells.

2. Effect of skin function: The greasy base interferes with normal skin functions. They are irritant to the skin. O/w emulsion bases are more compatible with skin function & having cooling effect rather than healing effect & mix readily with skin secretions. The ointment base should not interfere with normal skin functions.

3. Miscibility with skin secretions: The skin secretions are oily as well as aqueous. Emulsion bases are readily miscible with secretions.

4. Freedom for irritant effect: Ointment base should not cause any irritation to the skin.

5. Compatibility with skin secretions: The ointment base should not react with skin secretions.

6. Emollient properties: Dryness & brittleness of skin cause dis-comfort, so ointment base should have emollient. Ex: Wool fat has the good emollient property.

7. Ease of application and removal: Water miscible bases are readily removed by simple washing with water.

II) Pharmaceutical factors:

1. Stability: Fats and oils obtained from animal and vegetable sources are liable to undergo oxidation unless they are suitably preserved. Liquid paraffin is also stable but on prolonged storage it gets oxidised therefore an antioxidant like tocopherol may be incorporated. 

2. Solvent properties: Most of the medicaments used in the preparation of ointment are insoluble in the ointment bases therefore they are finely powdered and distributed uniformly through the base. 

3. Emulsifying properties: Hydrocarbon bases can absorb only a small amount of aqueous substances where as animal fats can absorb an appreciable amount of water. 

4. Consistency: The ointments produced should be of suitable consistency. They should neither be too hard nor too soft. They should be with stand the climatic conditions. The consistency of an ointment can be adjusted by incorporating a suitable proportion of high melting point substances like hard paraffin, bees wax etc.

Method of preparation of ointment:

Ointment are prepared by four methods namely

1. Fusion method: This method is prepared when the base is hard & the medicaments are soluble in  the base. All the ingredients such as white soft paraffin, stearic acid are melted together. The medicament is then added to the melted base & stirred thoroughly until the melted base cools down & a homogenous product is formed.

Ex: Simple ointment, emulsifying ointment. 

2. Triturations method: This method is preferred when the base is soft & the medicaments are insoluble in the base. All the solid ingredients are finely powdered & passed through a sieve of appropriate size. Then the medicaments are insoluble in the base. All solid ingredients are finely powdered & passed through a sieve of appropriate size. Then the medicaments are triturated with a small amount of the base on the ointment slab with the help of stainless steel spatula. To this the remaining quantities of the base are added & triturated until the medicaments are homogeneously mixed with the base. The ointment is passed (if necessary) through an ointment until mill to remove the gritty particles.

Ex: Sulphur ointment, Boric acid ointment.

3. Chemical reaction method: Certain ointments containing free iodine combined iodine are prepared by chemical reaction method.

Ex: Ointment containing free iodine: Iodine is slightly soluble in most fats & oils. But when iodine is combined with Kl, I forms poly-iodides which are more soluble in water, alcohol & glycerine. The solvent used in this preparation should be non-volatile otherwise the medicament may crystallize when the solvent evaporates. So glycerine is choosen as solvent.

Formula: Iodine, KI, Glycerine, Wool fat, Yellow bees wax, Yellow soft paraffin.

Procedure: Dissolve iodine & Kl in glycerine using a glass motor. Melt the wool fat, yellow bee’s wax & yellow soft paraffin in a china dish over a water bath & stir well. Add the iodine solution to the melted base & mix thoroughly.

Storage: It is stored in well closed container and kept in a cool place.

Use: Used in the treatment of myalgia and arthritis.

Action: Iodine acts as anti-septic, disinfectant and counter irritant. Kl increases the solubility of iodine. Glycerine acts as a solvent. Wool fat, yellow soft paraffin acts as base.

4. Emulsification method: In emulsification method, an ointment emulsion is formed if a non-fatty liquid (one which is immiscible with fats) is distributed throughout a solid fat by trituration. Ex: Wool fat emulsion, Wool alcohol emulsion, Bees wax emulsion. Soap emulsion

Storage of ointments:

Containers: Generally ointments are packed in ointment jars or collapsible tubes. Amber coloured glass jars are used for light sensitive preparation. While filling the ointment jars care must be taken to avoid the entrainment of air, packing of ointments in collapsible tubes are more hygienic. Collapsible tubes are made up of tin.

Storage: Ointments should be stored in well closed containers and in a cool place. It should be protected from light, high temperature cause deterioration of ointments.

Labelling: “for external use only”

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