The popularity of topical formulations are gaining popularity in the pharmaceutical industry. They have successfully delivered the drugs to a specific site or area on the body as well as avoid fluctuations in the drug levels, intra, and inter-patient variations, and improve the patient’s cooperation or acceptance to the drugs.
In the topical formulation, the skin acts as the right medium for delivering the drugs that have both local as well as systemic effects. At the same time, the skin also acts as a mechanical barrier for the penetration of the drugs.
This is a result of topical drugs when applied, react among themselves as well as with the skin of the patient. For example, the drug used in the treatment of psoriasis could be effective because of the hydrating or soothing effects of the formulation.
The potency and purity of the molecules in the drugs depend on the ingredients used to prepare it. The transportation or delivery of the drug from the formulation to the site of action depends on both the mechanical barrier properties of the skin as well as the physicochemical properties of the drug. Therefore, it is essential to use the correct amount of formulation in topical drug development. Many pharmaceutical contract manufacturing companies provide formulation services.
Even a minute change in the formulation leads to significant differences in the efficacy of topical drugs. It is important that the molecules maintain the required properties such as dosage integrity, active duration, drug transportation, and other factors to ensure the delivery of the drug to the specified area or site.
Other major properties include pH, droplet nature, ionic size, relative amounts of water, and oil, viscosity, and stabilizers. Further, even the method of preparation of the drug has an impact on skin absorption and efficacy.
The selection of the right excipients for topical drug development is essential. Although the drug substance are efficient, their interaction with excipients may alter or affect the following:
- Ability to penetrate through the skin
- Ability to non metabolize in the skin
- Ability to stay dissolved at the right concentrations
- Capability to achieve the desired release rate once it enters the body
- Stability through shelf life
Apart from the excipients, there should be a focus on the choice of permeation enhancers while the topical formulation development is in their early stages. The major factors to be considered while choosing these are the dermis and epidermis. Dermatology pharmaceutical companies mostly develop these formulations. Another critical factor is the pH level of the formulation. The pH level should be carefully balanced and maintained as they can have severe side effects.
Say, it the formulation happens to be too acidic, it might burn the skin, and if it is too basic, it might have other types of effects on the skin. It is vital to take into consideration the reaction of pH at different layers in the skin.
On the whole, the right formulation of topical drug development is when all its ingredients like drug substance, excipients, and the target area are all in the required proportion. The formulation can be improvised or altered based on the skin type or properties and the properties of the drug substances.
The right formulation in topical drug development plays a crucial role and can either be a success or a complete failure. Additionally, getting the preparation right and as per the proportions or formulation saves a lot of money and time for the pharma manufacturing companies.