15. TOPICAL PREPARATIONS

TOPICAL PREPARATIONS: A TEACHER’S COMPREHENSIVE GUIDE

Welcome, future pharmaceutical scientists and healthcare professionals!

Topical preparations are meant to be applied on the external surfaces of the body, such as skin and other body cavities. They are used to treat pain and inflammation on the body surfaces, provide soothing effect to the skin, and nourish the skin. They include various types of preparations, such as ointments, creams, pastes, gels, liniments, lotions, suppositories, and pessaries.

As a pharmacy educator with years of experience teaching pharmaceutics, I have observed that students often find topical preparations challenging due to their diverse formulations and bases. Let me tell you: Topical preparations are essential for dermatological therapy—they deliver drugs directly to the site of action with minimal systemic side effects.

In this comprehensive guide, I will walk you through the fundamentals of topical preparations—ointments, creams, pastes, gels, liniments, lotions, and suppositories. I will cover their classifications, formulation, preparation methods, advantages, disadvantages, and differences. By the end of this article, you will have a thorough understanding of topical dosage form technology. Let us begin!

Dpharmguru’s exam insights:

Topical preparations are frequently tested in pharmacy exams. Remember: Ointments are semisolid with less powder content. Pastes have high powder content. Creams are emulsions (o/w or w/o). Gels are aqueous colloidal suspensions. Liniments are applied with friction. Lotions are applied without friction. Suppositories are inserted into body cavities. These are classic exam questions!

5.8. TOPICAL PREPARATIONS

5.8.1. Ointments

Ointments are semisolid formulations carrying medicaments that are designed for topical application. The ointment should be of such consistency that it can be easily rubbed on the skin. The ointment base contains the medicament in solution, suspension, or emulsion form.

5.8.1.1. Types of Ointments

• Hydrophobic/Lipophilic Ointments: Anhydrous, absorb only small quantities of water; use water-insoluble hydrocarbons like soft, hard, and liquid paraffin
• Water-Emulsifying Ointments: Hydrous, can absorb large quantities of water; contain hydrophobic fatty base with w/o agent (wool fat, wool alcohols, sorbitan esters)
• Hydrophilic Ointments: Blend of solid polyethylene glycols (PEG/macrogols) and liquid; water-miscible bases

5.8.1.2. Classification and Selection of Ointment Bases

Ideal Requirements of an Ointment Base:

• Physical Properties: Smooth texture, elegant appearance, non-dehydrating, free from gritty particles, non-greasy, non-staining, non-hygroscopic
• Physiological Properties: Non-irritating, should not affect skin function, compatible with skin secretions, low sensitisation index
• Application Properties: Easy to apply, washable with water, releases appropriate concentration of drug

Classification of Semisolid Bases:

• Oleaginous/Hydrocarbon Bases: Anhydrous, hydrophobic, non-washable (e.g., white petrolatum, white ointment, hard and liquid paraffin)
• Absorption/Emulsifiable Bases: Anhydrous, maintain consistency after absorbing water (e.g., wool fat, wool alcohol, beeswax, cholesterol, hydrous wool fat/lanolin)
• Emulsifying Bases: w/o emulsion bases (cold cream type, hydrous lanolin) and o/w emulsion bases (carbowaxes, PEG, hydrated gums)
• Water-Soluble (Greaseless) Bases: Oil-free, completely soluble in water (e.g., polyethylene glycol, polysorbates, macrogols)

5.8.1.3. Preparation of Ointments

• Trituration: Using mortar and pestle (small scale), ointment slab, or ointment mill (large scale)
• Fusion: Ingredients melted together with continuous stirring until congealed
• Chemical Reaction: Formation of ointments through chemical reactions (e.g., strong iodine ointment)
• Emulsification: Combining oily phase, aqueous phase, and emulsifying agent

5.8.1.4. Advantages of Ointments

• Easy to handle
• Chemically more stable than liquid dosage forms
• Directly applied to target area
• Preferred by patients sensitive to parenteral and oral routes
• Enhanced contact time between medicament and applied area
• Drugs undergoing first-pass metabolism can be given as ointments

5.8.1.5. Disadvantages of Ointments

• Bulkier than solid dosage forms
• Less stable than solid dosage forms

5.8.2. Creams

Creams are semi-solid dosage forms of medicaments consisting of one or more drug substances dissolved or dispersed in an appropriate base. They are semi-solid emulsions of oil and water with a soft consistency and light texture as compared to ointments.

Types of Creams

• Oil-in-Water (O/W) Creams: Oil dispersed in continuous aqueous phase; less greasy, easily washable; used as emollients
• Water-in-Oil (W/O) Creams: Water dispersed in continuous oily phase; more moisturizing, provide oily barrier; difficult to handle (e.g., cold creams)

5.8.2.1. Cold Cream

Cold creams are w/o type emulsions added with fats (generally beeswax) and perfuming agents. They are applied on skin to provide smoothness and remove makeup.

Formulation: White beeswax (20gm), Mineral oil (50gm), Distilled water (28.8gm), Borax (0.7gm), Perfume (0.5gm)

5.8.2.2. Vanishing Cream

Vanishing creams are o/w type emulsions, also known as day creams. They spread as thin oil-less film when applied on the skin, providing emollient and protective action.

Formulation: Stearic acid (24%), Potassium hydroxide (1%), Water (64%), Glycerine (10.5%), Perfume (0.5%)

5.8.2.3. Advantages of Creams

• Provide prolonged contact time at application site
• Non-irritating
• Easily washed off with water
• Easily spread at application site

5.8.2.4. Disadvantages of Creams

• Not as stable as ointments
• More hydrophilic than other semi-solid preparations
• Greater chance of contamination

5.8.3. Pastes

Pastes are semisolid preparations intended for external use on the skin to provide a protective covering. They contain high powder content which provides a stiff and thick consistency.

5.8.3.1. Bases of Pastes

• Hydrocarbon Bases: Soft paraffin and liquid paraffin (e.g., Compound zinc paste, Coal tar paste)
• Water Miscible Bases: Emulsifying ointment (e.g., Resorcinol and sulphur paste, Zinc and coal tar paste)
• Water-Soluble Bases: Used for extra pharmacopoeial formulations (e.g., Dental pastes)

5.8.3.2. Preparation of Pastes

• Trituration Method: Used when active drug is not soluble in the base
• Fusion Method: Used when different ingredients with varying melting points are added

5.8.3.3. Difference between Ointments and Pastes

5.8.4. Gels or Jellies

Gels or jellies are semisolid gels having suspensions containing either small inorganic particles or large organic molecules interpenetrated by a liquid. They are transparent or translucent non-greasy semisolid gels.

5.8.4.1. Types of Gels/Jellies

• Medicated Jellies: Contain extensive amount of water; used as vehicles for water-soluble medicaments
• Lubricants: Used for catheters, electrodiagnostic equipment, and rubber gloves
• Miscellaneous Jellies: Patch testing, electrocardiography

5.8.4.2. Formulation of Gels/Jellies

• Tragacanth: 2–3% for lubricants, ~5% for dermatological vehicles
• Sodium Alginate: 1.5–2% as lubricant, 5–10% as dermatological vehicle
• Pectin: Used with glycerol as dispersing agent and humectant
• Starch: Starch glycerine B.P.C. product
• Gelatin: 2% gelatin forms a gel on cooling

5.8.4.3. Advantages of Gels

• Easily washed off
• Non-toxic
• Non-greasy
• Easily spread on application site

5.8.4.4. Disadvantages of Gels

• Slow and sustained action
• May irritate skin due to gelators and additives
• Require proper packaging to maintain stability

5.8.4.5. Differences between Gels and Creams

5.8.5. Liniments

Liniments are liquid or semisolid dosage forms applied with friction over unbroken skin. They are either massaged on the skin to produce counterirritant or stimulant action, or applied on a warm dressing to produce analgesic and soothing effect.

5.8.5.1. Classification of Liniments

• Based on Therapeutic Effects: Analgesic, Irritant, Anti-inflammatory, Astringent, Fungicidal
• Based on Dispersion Medium: Fatty, Alcohol, Soap-alcohol
• Based on Disperse Systems: Homogenous, Heterogeneous

5.8.5.2. Advantages of Liniments

• Quickly absorbed by the skin
• High bioavailability
• Easily applied
• Less expensive

5.8.5.3. Disadvantages of Liniments

• May cause redness, inflammation, rash
• May cause permanent thinning of the skin

5.8.6. Lotions

Lotions are liquid preparations intended to be applied externally on broken skin without friction. They possess low to medium viscosity and provide local cooling, soothing, or protective actions.

5.8.6.1. Examples of Lotions

• Calamine Lotion I.P.: Calamine (15g), Zinc oxide (5g), Bentonite (3g), Sodium citrate (0.5g), Liquefied phenol (0.5ml), Glycerine (5ml), Rose water q.s. (100ml)
• Salicylic Acid Lotion B.P.: Salicylic acid (2g), Castor oil (1ml), 95% Alcohol q.s. (100ml)

5.8.6.2. Advantages of Lotions

• Provide hydration and moisturising effect
• Provide anti-aging effect
• Prevent skin from drying and cracking
• Protect skin from harmful UV radiation

5.8.6.3. Disadvantages of Lotions

• May cause skin allergies due to synthetic chemicals
• Long term use may clog pores
• May cause breathing problems from synthetic fragrances

5.8.6.4. Difference between Lotions and Liniments

5.8.7. Suppositories and Pessaries

Suppositories are medicated solid or semisolid dosage forms meant for insertion into body cavities like rectum, vagina, or urethral tract. They melt, disintegrate, or dissolve at body temperature. Pessaries are suppositories designed for insertion into the vagina.

5.8.7.1. Types of Suppositories

• Rectal Suppositories: Tapered at one or both ends; adult weight ~2g, infant weight ~1g
• Vaginal Suppositories (Pessaries): Globular or oviform-shaped; weight ~5g
• Urethral Suppositories (Bougies): Cylindrical-shaped; female: 5mm × 50mm × 2g; male: 5mm × 125mm × 4g
• Nasal Bougies: Thinner, 8cm size, ~1.2g weight
• Ear Cones (Aurinaries): Cylindrical-shaped, ~1g weight

5.8.7.2. Suppository Bases and their Classification

• Oleaginous/Fatty Bases: Theobroma oil (Cocoa butter), Synthetic triglycerides
• Aqueous/Water Soluble Bases: Glycerinated gelatin, Polyethylene glycol polymers
• Emulsifying Bases: Massa Esterinum, Witepsol, Massupol

5.8.7.3. Preparation of Suppositories

• Hand Rolling and Moulding: Traditional method for small quantities using cocoa butter
• Compression Moulding: Using compression machines
• Fusion Moulding: Melting the base and pouring into moulds

5.8.7.4. Advantages of Suppositories

• Improved enzymatic drug stability
• Avoidance of hepatic first-pass metabolism
• Higher drug load
• Lymphatic delivery
• Constant and static environment
• Suitable for patients with swallowing difficulty
• Avoidance of overdosing

5.8.7.5. Disadvantages of Suppositories

• Patient acceptance and compliance issues
• Potential for non-specific drug loss
• Limited fluid in rectum
• Formulation difficulties
• Expensive compared to tablets

Dpharmguru’s exam insights:

Suppositories are frequently tested. Remember: Theobroma oil (cocoa butter) is the classic suppository base. It melts at body temperature (30–35°C). Avoid overheating as it causes polymorphism. Glycerinated gelatin is used for vaginal suppositories. PEG bases are water-soluble and dissolve in body fluids. These are classic exam questions!

SUMMARY

Topical preparations are essential dosage forms for dermatological therapy. This guide covered:

• Ointments: Semisolid formulations with less powder content; prepared by trituration, fusion, or emulsification
• Creams: Semi-solid emulsions; o/w (less greasy) and w/o (more moisturizing)
• Pastes: High powder content; stiff and thick consistency; provide protective covering
• Gels: Transparent non-greasy semisolids; aqueous colloidal suspensions
• Liniments: Applied with friction over unbroken skin; counterirritant action
• Lotions: Applied without friction on broken skin; cooling and protective action
• Suppositories: Inserted into body cavities; melt or dissolve at body temperature

As I always tell my students: “Topical preparations are the skin’s best friend—they deliver treatment exactly where it’s needed, with minimal side effects.”

REFERENCES AND FURTHER READING

• Pharmacy Council of India (PCI). (2022). Pharmaceutics Syllabus. New Delhi: PCI.
• Aulton, M. E., & Taylor, K. M. G. (2018). Aulton’s Pharmaceutics: The Design and Manufacture of Medicines (5th ed.). Elsevier.
• Allen, L. V., & Ansel, H. C. (2014). Ansel’s Pharmaceutical Dosage Forms and Drug Delivery Systems (10th ed.). Wolters Kluwer.
• Lachman, L., Lieberman, H. A., & Kanig, J. L. (2018). The Theory and Practice of Industrial Pharmacy (4th ed.). CBS Publishers.
• Subrahmanyam, C. V. S. (2019). A Textbook of Pharmaceutics. Vallabh Prakashan.

Disclaimer: This article is for educational purposes only and does not constitute medical advice. Always consult qualified healthcare professionals for medical concerns. Pharmaceutical regulations and guidelines may vary by region—always refer to your local regulatory authorities for specific requirements.

written by:
Dr. N. Sujith Kumar

Dr. N. Sujith Kumar is a pharmacy educator, Pharm.D graduate, and academic content creator from Jawaharlal Nehru Technological University Kakinada (JNTUK), where he completed his Doctor of Pharmacy (Pharm.D) degree between 2015 and 2021. He has more than 7 years of experience creating pharmacy educational content, writing study materials, and reviewing academic articles for pharmacy students. He has also contributed guest articles to pharmacy education platforms, including PharmD Guru. At D.PharmGuru, his work focuses on simplifying complex Diploma in Pharmacy (D.Pharmacy) subjects into easy-to-understand notes, practical explanations, and exam-oriented educational resources for students across India. His areas of focus include Human Anatomy and Physiology, Pharmaceutics, Pharmacology, Pharmaceutical Chemistry, Hospital and Clinical Pharmacy, and other core D.Pharmacy subjects.

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