Ointments, Creams, Pastes and Gels Lecture 11 Spring 2024 PDF

1 Learn different types of topical dosage forms Learn about different types of ointment bases Differentiate between ointments, creams, pastes and gels 2 Ointments are soft, semisolid preparations intended for external application. Ointments may be medicated or non-medicated ✓ Medicated - those with...

1 Learn different types of topical dosage forms Learn about different types of ointment bases Differentiate between ointments, creams, pastes and gels 2 Ointments are soft, semisolid preparations intended for external application. Ointments may be medicated or non-medicated ✓ Medicated - those with medicaments for treatments of cutaneous (skin diseases). Examples: Sulfur Ointment, Zinc Oxide Ointment ✓ Non-medicated - also referred to as “ointment bases” : Use as such for their emollient or lubricating effect or use as vehicles in medicated ointments. Example: White Ointment 3 The ointment bases are used as: ✓ Emollient or lubricating agent: to make skin soft and more pliable ✓ Protective barriers: Serve as physical barrier ✓ Vehicles in the preparation of medicated ointments. 4 Classification of ointment bases: 1).Hydrocarbon (Oleaginous) base 2).Absorption bases (Anhydrous) 3).Water-removable bases 4).Water-Soluble Bases 5 Oleaginous/Hydrocarbon bases Emollient effect: hydrates skin due to sweat accumulation Occlusive dressing Difficult to wash-off/remove Small amount of water can be incorporated into it with difficulty and can be protective to water labile drugs such as tetracycline and bacitracin. Is greasy and can stain clothing. *From S. Hoag, U Maryland 6 (a) Petrolatum, USP: This is a mixture of semisolid hydrocarbons obtained from petroleum. Melting point 38o-60oC. White petrolatum is decolorized Petrolatum (Commercial Product: Vaseline) (b)Yellow ointment, USP-95% (w/w) petrolatum and 5% (w/w) yellow wax (c) White ointment USP 95% (w/w) white petrolatum and 5% (w/w) white wax (bleached and purified yellow wax) (d) Paraffin, NF – It is a purified mixture of solid hydrocarbons obtained from petroleum. It is used to stiffen oleaginous semisolid ointment bases. (e) Mineral oil, USP – It is a mixture of liquid hydrocarbons obtained from petroleum. It is used as levigating agent. Commonly known as liquid petrolatum. 7 There are two types of absorption bases: a. Those that permit the incorporation of aqueous solutions to become water in oil emulsions. Examples: i. Hydrophilic petrolatum, USP (3% cholesterol in white petrolatum) ii. Anhydrous Lanolin, wool-wax iii. Aquaphor (6 parts wool-wax alcohols and 99 parts of aliphatic hydrocarbons). 8 (b) Absorption bases are already water in oil emulsions which have the ability to absorb additional water. Example: Cold Cream (w/o emulsions) 9 Absorption bases (anhydrous) Emollient Occlusive Absorbs water Greasy W/O emulsion Emollient Occlusive Contains water, absorbs additional water Greasy 10 O/W emulsion These bases can be diluted with water or with aqueous solution. The water removable bases consist of 3 parts: an oil phase, water phase and emulsifiers. Example: Acid Mantle Cream® Vanishing cream: o/w emulsion contains large % of water and humectant. An excess of stearic acid in the formula helps to form a thin film when the water evaporates. 11 Water-washable, easier to remove Non/less greasy Can be diluted with water Non/less occlusive Better cosmetic appearance Better compliance 12 Water-soluble bases contain only water-soluble substances, they are water removable and “greaseless”. Example: Polyethylene Glycol Ointment USP 13 Water soluble and washable Non-greasy Non/less occlusive Lipid free Synthetic base Relatively inert Does not support mold growth Little hydrolysis, stable May dehydrate skin and hinder percutaneous absorption 14 The following factors should be checked: 1. Release rate of the particular drug from the ointment base. 2. Enhancement of percutaneous absorption. 3. Stability and incompatibility of the drug in the ointment base. 4. Drug influence on the consistency or other features of the ointment base. 5. Desirability of occlusion 6. Desire for easy removable 15 1. Non-irritating, non-dehydrating, non-greasy 2. Compatible with common medicaments 3. Stable 4. Easily removable with water 5. Should have good absorptive properties (water and other aqueous liquids) 6. Good release properties of the drug from the base. 16 1. Mechanical incorporation: components are mixed until a uniform preparation is attained. 1. Fusion: All or some components are combined by being melted together and cooled with constant stirring until congealed The choice of a method depends upon the drug used and the physical properties of the constituents of the base. 17 Involves both solid and liquid incorporation A spatula with a long, broad blade should be used Insoluble substances should be powdered finely in a mortar and mixed with an equal amount of base until a smooth mixture is obtained. The rest of the base is added in increment. Levigation of powders into small portion of base is facilitated by the use of levigating agents. 18 Levigating agents: ✓ Mineral oil for oily bases or bases where oil are the external phase ✓ Glycerin for bases where water is the external phase. ✓ Levigating agent should be equal in volume to the solid material. 19 Used when the base contains solids that have higher melting points. Used for solid medications that are readily soluble in melted bases. The oil phase should be melted separately, starting with materials having the highest melting point. The ingredients in the water phase are combined and heated separately to temperature equal to or above that of the oil phase. The two phases are them combined. If a w/o system is desired, the hot aqueous phase is incorporated into the hot oil phase with agitation. Volatile materials are added after the melted mixture cools to desired temperature. 20 Microbial Content: ✓ Meet acceptable standard for microbial ✓ Must contain antimicrobial preservatives Minimum Fill Test – net weight and volume Packaging, Storage, and Labeling – metal, plastic tubes, jar ✓ Well close containers, light sensitive, light resistant ✓ Labeling- type of base used (water soluble or insoluble) Additional Standards ✓ Examine the viscosity ✓ In-vitro drug release to ensure within lot and lot-to-lot uniformity 21 Two different types of containers are most commonly used for packaging of ointments: Ointment jars Tubes 22 Creams are semisolid emulsion systems with a creamy white appearance. Creams are intended to be applied to the skin or certain mucous membranes for protective ,therapeutic, or prophylactic purposes especially when occlusive effect is not necessary Creams can be classified as: (i) Oil-in-water (O/W) creams (ii) Water-in-oil (W/O) creams 23 1) Oil-in-water (O/W) creams foundation creams hand creams shaving creams 2) Water-in-oil (W/O) creams cold creams emollient creams 24 Properly designed O/W creams make a good topical drug delivery system with: (i) pleasing appearance (ii) good feeling after application (iii) non greasy and washable (iv) suitable for oozing wounds 25 Composition: An ointment normally consists of 80% oil and 20% water. Whereas the percentage ratio of water to oil in creams is 50:50 However, there are some topical cream products, which may have much lower oil component as well. Spreadability: Ointments are greasier in nature and also have thicker consistencies Hence, you may find it difficult to spread ointments over large areas of the skin Creams on the other hand are lighter in consistencies, hence often work better to cover large areas 26 Absorption through skin: Creams are absorbed into the skin. Whereas ointments stay longer on the surface of the skin and not get absorbed into the skin. Hence ointments are often prescribed for dry skin, as they keep the skin moist for a longer period of time, thereby promoting healing faster. Whereas due to high water content in creams, they cause the skin to dry up faster. Therefore, they are a better option for greasy and oily skin. 27 Pastes are ointment-like preparations into which high percentages of insoluble solids have been incorporated. This percentage can be as high as 50% by weight. Pastes are usually stiffer (due to the presence of solids), less greasy and more absorptive than ointments. Starch, zinc oxide, calcium carbonate, and talc are generally used as solid phases in a paste. 28 Pastes make good protective barriers on the skin. The high surface area of the solid helps to absorb the noxious chemicals before they reach the skin. This explains their use in the treatment of diaper rash. Example: Butt paste (contains zinc oxide) 29 A gel is a semi-solid, jelly-like material that can have properties ranging from soft and weak to hard and tough. Gels are crosslinked system, which may exhibit no flow when at rest. Gels are mostly liquid, yet they behave like solids due to a three-dimensional crosslinked network within the liquid. It is the crosslinks within the fluid that give a gel its structure (hardness) and contribute to stickiness. 30 Hydrogels Hydrogel (also called aquagel) is a network of polymer chains that are hydrophilic.Usually water is the dispersion medium in these gels. Flexible due to significant water content. Organogels An organogel is composed of a liquid organic phase entrapped in a three-dimensionally cross-linked network. 31 Creams are best when covering large areas of the skin or to avoid the greasiness associated with an ointment. Wet or "weeping" skin lesions, such as eczema or poison ivy, are best treated with a cream (or gel) Ointments are best when treating dry skin conditions, such as psoriasis. Ointments allow greater penetration of the active ingredient in the topical medication, whether it is an antibiotic, steroid, or anti-fungal medication. The best moisturizers are in ointment form. Ointments may be better to use on sensitive skin since many creams are manufactured with sensitizing preservative Lotions: Are applied to areas where friction may occur, between the thighs or under the armpits 32 Concept: Decision tree of topical dosage form nomenclature Ref: Basic principle and application of pharmacy practice, Dash et al., Chapter 11, page 244 33 Concept: Classification of dosage forms Ref: Basic principle and application of pharmacy practice, Dash et al., Chapter 11, page 245 34 Concept: Different ointment bases Ref: Basic principle and application of pharmacy practice, Dash et al., Chapter 11, page 245 35 The major advantages of semisolid dosage forms include their demonstrated ability to readily incorporate a wide variety of hydrophilic and hydrophobic drugs to reduce the undesirable effects arising from the presystemic metabolism, and to minimize unnecessary fluctuations in drug concentration, which in turn will significantly enhance the efficacy of the incorporated drug. Topical delivery Limited applications (Disadvantage) 36 True/False True (Usually) Topical dermatological products: deliver drug into skin in treating skin disorder, target is skin Transdermal Products: deliver drug through skin to general circulations for systemic effects 37 Ointment base capacity to accept the volume required. Example: Very small amount of aqueous water can be incorporated in oleaginous bases. Aqueous solution need to be added to hydrophilic bases than incorporated into hydrophobic bases. Final product should retain its consistency and should not become too soft. 38 Eyes Nasal cavity Vagina Rectum 39 Percutaneous absorption (Will be covered later on) Structure of skin Physicochemical properties of drugs/excipients Vehicle used in formulation Condition of skin Additional agent to increase percutaneous absorption: Penetration enhancers, Chemical methods, electrical methods, Sonophoresis (microwaves, ultrasound waves etc.) 40 Review Questions 1 Which of the following is a property of water removable bases? A) Cannot not be removed from water B) greasy C) Can be diluted with water D) Occlusive 41 Review Questions 2 Which semisolid preparation contains the larger proportion of solids (up to 50%) ? A)Ointment B) Cream C) Pastes D)Gels 42 Review Questions 3 Which is a semisolid emulsion systems with a creamy white appearance having spreadibility over large area of skin ? A)Ointment B) Pastes C) Creams D)Absorption base 43 Review Questions 4 White petrolatum is_______________base. A) Water soluble B) Oleaginous C) Water removal D) Hydrophilic 44 Pharmaceutics: Basic Principles and Application to Pharmacy Practice by Dr Dash ▪ Chapter 11- Semi solid dosage forms Ansel’s Pharmaceutical Dosage Forms and Drug Delivery Systems; ▪ Chapter 10- Ointments; Creams and Gels 45