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Vehicles and Formulations in Dermatology
- 1. VEHICLES AND FORMULATIONS IN DERMATOLOGY Dr. Nishkarsh Chugh PGJR1 Dermatology
- 2. INTRODUCTION • A vehicle is a substance incorporated into a topical preparation in order to facilitate drug delivery by bringing the drug in contact with the skin.
- 3. IMPORTANCE • The type of vehicle may determine the effectiveness of the drug since the bioavailability of a drug may depend on its vehicle formulation • Drugs are incorporated in vehicles in concentrations which are maximally effective • Vehicles themselves may have therapeutic effects such as occlusion, protection, cooling, emollient, or astringent effect
- 4. PREREQUISITES • Physically and chemically stable • Nonirritating • Nonallergenic • Easily applicable • Should not inactivate the drug • Cosmetically and therapeutically acceptable to the patient
- 5. CONSTITUENTS Constituents Examples Lipids Petrolatum, Glycerin, Cetyl Alcohol, Stearyl Alcohol, Isopropyl Myristate, Squalene, Stearic Acid, Lanolin, and Shea Butter Emulsifying Agents Cholesterol, Polysorbates, Lanolin, Sodium Lauryl Sulfate, Sodium Laureth Sulfate, and Polyethylene Glycol Humectants Propylene Glycol and Sorbitol Solvents Alcohol, Acetone, Ether, Glycerin, and Water Stabilizers and Preservatives Benzyl Alcohol, Chlorocresol, Parabens, and Potassium Sorbate Thickening Agents Bee’s wax, Carbomer, and Polyethylene
- 6. FORMULATIONS Based on the composition of vehicles and ingredients, various topical formulations and drug delivery systems have evolved
- 7. CLASSIFICATION OF FORMULATIONS Liquids Solutions (a) Aqueous solutions: Wet dressings, soaks, and baths (b) Alcoholic solutions: Tinctures, paints, varnish, sprays Lotions Solid-in-liquid (shake lotions) and liquid-in-liquid Liniments Semisolids Creams Lipophilic creams, hydrophilic creams, ambiphilic creams, barrier creams Ointments Hydrophobic, water-absorbing, Hydrophilic Gels Pastes Hard pastes, soft pastes, drying pastes Solids Powders, poultices, tapes, and plasters
- 8. WET DRESSINGS • Actions: 1. Antipruritic 2. Vasoconstrictive 3. Cleansing 4. Keratolytic • Types: 1. Open 2. Closed 3. Wet-wrap therapy, LIQUIDS – AQUEOUS SOLUTIONS
- 9. SOAKS AND BATHS • They are used for the treatment of more widespread and less exudative lesions. • Types: 1. General cleansing baths 2. Medicated baths 3. Baths for specific body areas • Bathing for a prolonged period may cause hydration of the stratum corneum with resultant maceration of the skin. Hence, the period of each bath should not be for more than 30 minutes. Prolonged bathing also causes drying of the skin with resultant irritation. LIQUIDS – AQUEOUS SOLUTIONS
- 10. TINCTURES • Topical alcoholic solutions, which enable the delivery of a considerable amount of active ingredients at a particular site without causing any unwanted cosmetic side effect. • They are applied to skin sites such as scalp which cannot be irritated very easily. • Prolonged use may cause drying. LIQUIDS – ALCOHLIC SOLUTIONS
- 11. PAINTS/ COLLODION • Paints are liquid preparations applied to the skin with a brush. • It leaves an adherent film on the skin after drying, which allows the dissolved drug to remain in contact with the skin for a prolonged period, e.g., collodion flexide used as a vehicle for salicylic acid and lactic acid for the therapy of warts. • They may stain the skin and mucosa. LIQUIDS – ALCOHLIC SOLUTIONS
- 12. VARNISHES/LACQUERS • Special types of tinctures in which the alcohol leaves a thick film after evaporation • Advantages: 1. Better adherence 2. Localized action 3. Easy preparation 4. It is preferable in case of elder patients and patients receiving multiple medications so as to avoid drug-drug interactions LIQUIDS – ALCOHLIC SOLUTIONS
- 13. SPRAYS/AEROSOLS • They are used to deliver droplets of a drug over a wide surface area. • The drug is left behind after evaporation of the carrier. • Advantage: 1. Ease of application, specially on hair bearing areas • Disadvantages: 1. Expensive 2. Not Eco Friendly LIQUIDS – ALCOHLIC SOLUTIONS
- 14. LOTIONS • Lotions have a soothing, cooling, drying, and anti-inflammatory effect on the skin. They may protect, relieve itching, and cleanse the skin. • Hence, they are indicated in acute and subacute dermatoses which are not oozing and weeping. • Types: 1. Solid in liquid lotions (shake lotion) 2. Liquid-in-liquid lotion (oil-in-water) • They are suitable for use on oily skin and in intertriginous areas. • However, because of their drying effect, they are unsuitable for application on dry and ichthyotic skin as well as in chronic dermatitis. LIQUIDS – LOTIONS
- 15. LINIMENTS • Liniments or balms are nonalcoholic solutions of drugs in oil or alcoholic solutions of soaps. • They are used as emollients, analgesics, astringents, antipruritics, and counterirritants. LIQUIDS – LINIMENTS
- 16. CREAMS • Creams are two-phase, semisolid emulsions where one immiscible liquid is dispersed in another. 1. Lipophilic creams (water-in-oil), e.g., cold creams: • The inner, watery phase is dispersed as fine droplets within the lipophilic outer phase. The oily outer phase prevents mixing with water, hence they cannot be easily washed off. • They are moderately occlusive and hence act as emollients. However, the occlusive effect can worsen acute inflammatory dermatoses. • When cold creams are applied to the skin, the emulsion is disrupted by the warmth of the skin. A greasy residue is left behind and the released water evaporates to provide the cooling effect. • Lipophilic creams also lubricate the skin and soften scales, and are mainly used in chronic inflammatory dermatoses such as psoriasis, atopic dermatitis, and hypertrophic lichen planus. SEMISOLIDS - CREAMS
- 17. CREAMS 2. Hydrophilic creams (oil-in-water), e.g., vanishing creams • The inner phase is composed of oil or fat droplets dispersed in the outer watery phase. • When the water evaporates, it has a cooling effect and the thin film of oil left behind has a drying effect. • The cooling effect is advantageous in treating inflammatory conditions. • However, the drying effect can cause tightness, pruritus or asteatotic dermatitis on long-term use. • They have a soft consistency, are minimally greasy, and can retain moisture. • Hydrophilic creams are useful in nonscaly subacute and chronic dermatoses, but are contraindicated in dry skin disorders such as ichthyosis and atopic dermatitis. SEMISOLIDS - CREAMS
- 18. CREAMS 3. Ambiphilic creams • They do not contain two clear phases and hence are neither lipophilic nor hydrophilic creams. • They can be easily spread and removed and hence are easily washable. • They are less cooling and more lubricating than hydrophilic creams. • They can be mixed with water, oils, or fats. • They can be used in various skin types and in subacute to chronic dermatoses. • However, they are not useful in weeping dermatoses or very dry skin. SEMISOLIDS - CREAMS
- 19. CREAMS 4. Barrier creams • It contain water-repellent substances such as dimethicone, which protect the skin against irritation, incontinence, or repeated hydration. • They are useful in the treatment of diaper dermatitis and decubitus ulcers. SEMISOLIDS - CREAMS
- 20. OINTMENTS • Ointments are semisolid, soft to firm, greasy formulations. • In contrast to creams, they are single phase substances in which liquid and solid substances are dispersed. • Ideal Ointment: 1. Inert 2. Smooth 3. Odorless 4. Physically and chemically stable 5. Easily spread 6. Should not produce sensitization or irritation of skin. SEMISOLIDS - OINTMENTS
- 21. OINTMENTS 1. Hydrophobic ointments • They are one-phase ointments which are water-free and not miscible with water. • They soften the stratum corneum, reduce transepidermal water loss, increase penetration by causing occlusion, and form a protective covering over the skin. • They possess uniform consistency and can easily be spread evenly. • They cause loosening of crusts and scales, and are useful for the treatment of hyperkeratotic and chronic disorders. • Their components are mostly nonallergenic. However, they may cause maceration due to swelling of the stratum corneum. They may retain heat SEMISOLIDS - OINTMENTS
- 22. OINTMENTS 2. Water-absorbing ointments • They absorb large amounts of water. • They are of two types: 1. Water-in-oil emulsions 2. Oil-in-water emulsions 3. Hydrophilic ointments • They are medications in a base containing polyethylene glycol, which acts as a lubricant. • They are completely miscible and may convert into liquids by taking up large amounts of water. • They are not only hydrophilic but also hygroscopic, by virtue of which they can be used to prepare antiseptic and antifungal ointments. SEMISOLIDS - OINTMENTS
- 23. GELS • Gels are soft, semisolid preparations, translucent to transparent in appearance. • They liquefy upon coming in contact with the skin and form thin, greaseless films upon drying. • Types: 1. Lipophilic gels (oily gels) 2. Hydrophilic gels (hydrogels) SEMISOLIDS - GELS
- 24. PASTES • Pastes are prepared by incorporating fine, powdery materials such as zinc oxide, starch, talc, aluminium oxide into an ointment base such as petrolatum. • They soothe and dry the skin and are used along with dressings as paste bandages. • Pastes provide protection from mechanical forces such as rubbing and scratching and also from occlusion and hydration. • Hence, they are useful for the treatment of subacute and chronic dermatoses, psoriasis, and ulcers SEMISOLIDS - PASTES
- 25. POWDERS • Powders are solid preparations used to dry or cool the skin by increasing evaporation, reducing friction, and acting as antipruritic medications. • Powders are used to deliver antibiotics (e.g., combination of polymyxin B, bacitracin, and neomycin) or antifungals. • They can also be used for the treatment of erosions and ulcers. • They are commonly used in intertriginous areas and feet. • When applied on wounds, talc has occasionally caused formation of granulomas (talc granuloma) and starch can cause overgrowth of Candida albicans. SOLIDS - POWDERS
- 26. POULTICES • Poultices are wet, solid masses of particles applied to exudative lesions such as bed sores and leg ulcers. • They are used to cleanse the lesions and absorb the exudates. SOLIDS - POULTICES
- 27. TAPES AND PLASTERS • Tapes and plasters are delivery systems used to keep the active ingredient in close contact with the skin causing enhanced penetration. • Tapes and plasters are also used to protect wounds and speed healing. • However, tapes can cause occlusion leading to maceration and occasional irritation. SOLIDS – TAPES AND PLASTERS
- 29. CHOOSING THE IDEAL FORMULATION 1. Depending on nature of dermatosis: 1. Wet or Oozy Skin Conditions: Cream, Lotion, Drying Pastes 2. Inflamed skin: Wet Compress, Soaks followed by Creams and Ointment 3. Dry Scaly Skin: Ointments, Oil 4. Cracks and Sores: Bland Application
- 30. CHOOSING THE IDEAL FORMULATION 1. Depending on the site: 1. Palms and Soles: Ointment or Cream 2. Skin Folds: Cream, Lotion or Paints 3. Hairy Areas: Lotion, Solution, Gel, Foam, Sprays 4. Mucosal Surface: Nonirritating Formulations 5. Scalp: Tinctures
- 31. SUMMARY
- 33. MODERN DRUG-DELIVERY SYSTEMS Microsponges Microgels Liposomes Niosomes Transferosomes Ethosomes Foams
- 34. Thank You Dr. Nishkarsh Chugh PGJR1 Dermatology
Editor's Notes
- Some vehicles may have multiple properties
- Some vehicles may have multiple properties
- 1. due to evaporation and consequent cooling resulting in increased threshold for itching and pain 2. due to cooling resulting in decrease in the augmented blood flow at the inflammation sites 3. They clean the inflamed areas of exudates and debris and maintain the drainage of these areas. 4. They macerate the skin resulting in a keratolytic effect They are indicated in acute dermatoses where the inflammation is accompanied by exudation and oozing. On the other hand, dressings covered with plastic, oil cloth, or other impermeable covers are called closed wet dressings. They cause maceration by retaining heat. They are indicated in the treatment of cellulitis and abscesses. two layers of tubular bandages or gauze are applied. The first inner layer is moist and the outer layer is dry. They are used to treat particularly severe pruritic disorders and refractory atopic dermatitis
- 1. to remove dirt, debris, scales, and residues of previous medications 2. containing medications such as oatmeal, tannic acid, potassium permanganate, sulfur, or tar (useful due to their antipruritic, anti-eczematous, anti-seborrheic, anti-psoriatic, macerating, and softening actions), as also baths used for delivery of medication as in psoralen and ultraviolet A (PUVA) 3. such as hipbaths.
- The active ingredient may be corticosteroids, keratolytics, and antimicrobials.
- They may bind to the secretions causing exacerbation of disease and exposure to secondary infections if applied to oozing lesions. A shake lotion is a compound containing suspended particles. They are basically oil-in-water creams to which additional water is added. Hence, they have more similarity to creams rather than shake lotions.
- The two phases are usually a lipophilic phase and a watery phase.
- Addition of more water first results in a hydrophilic cream. Further addition of water results in the formation of an oil-in-water creamy lotion (milk). However, if oil is added to the ambiphilic cream a lipophilic cream is produced. Hence, ambiphilic creams have the advantage of being manipulated with extra oil or water to match the nature of the disease in which they are to be used.
- 1. Water-in-oil emulsions are ointments insoluble in water and difficult to wash off. Due to the presence of emulsifiers, they can take up large amounts of water. Hence, they have less occlusive properties than hydrophobic ointments and are easy to mix. They are useful for the treatment of dry skin and chronic dermatoses, but are contraindicated for application on oily skin or for treating acute inflammatory disorders. 2. Oil-in-water emulsions are ointments which take up large quantities of water and easily washed away with water. They have more spreadability than water-in-oil emulsions. Hence, they can be used to treat hairy areas or for short-period applications on normal or weeping skin. The application should be on skin that is moist. They do not occlude the skin and hence maceration is minimal. However, when applied to dry skin they may increase the dryness.
- Lipophilic gels (oily gels) are prepared from liquid paraffin or fatty oils. Their occlusive property renders them suitable for the treatment of chronic hyperkeratotic and papulosquamous disorders, atopic dermatitis, and ichthyosis. They should not be used on moist or oily skin. Hydrophilic gels (hydrogels) contain water, glycerin, or propylene glycol along with a cellulose derivative. Following application, the aqueous part evaporates depositing a thin film on the skin. They have a cooling effect when applied. Antiinflammatory and antipruritic drugs are applied as hydrogels. They are non-greasy and easily miscible with water. They are useful for the treatment of diseases on oily skin and mucosal areas. However, they cannot be used on dry skin and can cause excessive drying on prolonged use.
- Examples of commonly used plasters are salicylic acid plasters for warts and corns, and tapes containing corticosteroids
- Microsponges: It consists of porous microspheres that provide sustained release of drug, therefore reducing irritation. E.g. Antidandruff Shampoos Microgels: These are polymers that enhance stabilization and penetration of drugs and diminish irritancy. E.g. Tretinoin Gel Liposomes: These are uni-multimellar spherical shells of phospholipids in aqueous medium that may enhance percutaneous absorption. E.g. Liposomal Vitamin C Niosomes: Non-ionic surfactant based liposomes which are structurally similar to liposomes. E.g. Niosomal Methotrexate Gel TRANSFEROSOMES : a drug delivery technology based on highly deformable, ultraflexible lipid vesicles that penetrate the skin surface when applied topically. Adv- unique as it can accommodate hydrophillic , lipophic and amphiphilic drugs. e,.g. terbinafine transferosomes ETHOSOMES : soft , malleable vesicles composed of ethanol phospholipids, and water. enhances penetration by dissolving the intracellular bilayer in stratum corneum. Adv : greater penetration into deeper layers of skin. e.g. acyclovir, minoxidil FOAMS : well accepted but costly new foams have ability to deliver the active drug at increased rate because it uses “rapid permeation” pathway for delivery of drug. e.g. clofoams, betafoams.