Topical drug products are a convenient method for delivering medications directly to affected areas of the body. They also make up an important sector of the pharma industry. The topical drug delivery market totalled over $125.75 billion in 2025 and is forecast to reach $176.43 billion by 2030.
The nature of a topical product varies depending upon its use. Protective and barrier ointments are intended to protect healthy skin from harmful influences, whereas wound ointments are for use on acutely or chronically diseased skin. Absorption through the upper layers of skin is the primary focus in these products. However, there are also transdermal preparations that can be absorbed through the skin, such as transdermal hormone therapies and rheumatism ointments. In the prescription-only market, products are mainly glucocorticoid-containing creams, antifungals, and antibiotics. For over-the-counter products, there is a wide range of applications, including topical cold creams, herpes treatments, and anti-inflammatory preparations. Both small molecules and plant-based substances/extracts can be formulated into these products.
Semi-solid preparations, such as ointments, creams, gels, and pastes, can be either hydrophobic or hydrophilic, depending on their nature. A cream contains both a hydrophilic and an aqueous phase, whereas a gel is a liquid formulated with specific gelling agents.
Formulation and testing considerations
Developing a topical pharmaceutical product requires extensive research, testing, and expertise in a wide range of disciplines, including formulation, analysis, packaging, and labelling. The goal of formulation is to combine the active ingredients with carriers, stabilizers, and other agents to create a stable, effective, and patient-friendly product. There is no one-size-fits-all solution with each product, be it a cream, lotion, gel, or ointment, meaning each product requires precision and tailoring for the specific skin concerns or application.
For skin penetration to occur, the affinity to skin has to be greater than the affinity to the base material within the product. Solubility within the base of the product, melting point, and molecular size are all crucial to ensure a good product. The formulation must also consider stability to ensure that the cream remains stable throughout its shelf life; skin compatibility to avoid unwanted reactions from other ingredients; spreadability for ease of use; and a homogeneous appearance.
As with other delivery methods, such as oral dosing or injectables, bioavailability is important because it defines the rate at which the active product being absorbed into the skin reaches the desired target. The skin acts as a natural barrier to protect patients, which makes the challenge of topical delivery significant, but the skill of a formulator is to use the experience they have in product design to create products that can penetrate effectively.
There are several techniques in the formulation toolkit that can help improve bioavailability in topical formulations, as well as improve stability. Microemulsions can enhance bioavailability as they can penetrate through both the hydrophobic and hydrophilic pathways into the skin, and allow higher concentrations of API to be formulated without affecting stability. Additionally, liposomes can improve stability and act as carriers, and potentially aiding the delivery of actives to a specific site. Another technology involves the use of nanoparticles, which are typically less than 100 nm in size, to allow for easier penetration into the skin and increase the absorption and bioavailability of products.
As with every pharmaceutical product, rigorous testing is necessary. For topical products, these include skin compatibility tests, API release studies, and stability tests. Testing should determine diffusion capacity, dissolution rate, and dissociability, as well as parameters such as the distribution of the API between the phases of the base, the partition coefficient – which shows the distribution behavior between the ointment and skin – the solubility in skin fat and how much the active ingredient binds to skin proteins, and the particle size and distribution of the active ingredient. Of course, microbiological testing must also be undertaken.
Additional considerations: manufacture and packaging
Before large-scale production, small batches should be produced for initial testing – and to ensure that the process is robust and yields a consistent formulation. Based on the results, adjustments can be made before continuing. Scale-up manufacturing, with greater volumes, can bring about other challenges, which will vary depending upon the nature of the preparation and the specific raw materials that are needed. Typically, challenges arise from the miscibility of the formulation and the solubility of the raw materials and active ingredients, but these can be overcome by precise control of the temperature and mixing times. For creams, the level and selection of the correct emulsifiers is important. For gels, adequate gelling time must be allowed. In certain situations, specialized dispersion technology must be used.
When developing topical products, don’t forget to consider packaging design. This plays a crucial role because it can affect the stability, shelf-life and user-friendliness of the product. Squeeze tubes protect against contamination and allow for easy dosing, while jars allow easy access but may pose a higher risk of contamination. The choice of packaging should support the properties of the formulation and the nature of the end user. There is also a number of labelling regulations set by regulatory bodies that must be considered.
Because the topical drug product market is complex, access to specialized knowledge and resources is crucial. The understanding of the formulation, ingredient sourcing, manufacturing, testing, and packaging selection has great implications for the final result. Different disciplines will need to work together to achieve success. Innovators and manufacturers alike must be aware of the changing needs of the patients and the markets, and how to use innovations where possible to ensure that patients have access to the highest quality products.
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