US FDA issues draft norms on Transdermal & Topical Delivery Systems for quality product development
The US FDA has issued draft norms on Transdermal & Topical Delivery Systems for product development and quality considerations. This guidance provides recommendations to applicants and manufacturers of transdermal and topical delivery systems (TDS) regarding the pharmaceutical development and quality information to include in new drug applications (NDAs) and abbreviated new drug applications (ANDAs).
The industry is expected to revert by January 2020 with their suggestions to the draft. Transdermal delivery systems are designed to deliver an active ingredient or drug substance across the skin and into systemic circulation. While the topical delivery systems are designed to deliver the active ingredient to local tissue. Both delivery systems present similar manufacturing and quality control concerns and similar risks to patients.
According to medical experts, use of skin is an effective medium from which absorption of the drug takes place and enters the circulatory system.
Transdermal delivery systems can be broadly divided into matrix type and liquid or gel reservoir type delivery systems. While the matrix type includes additional layers and complex designs, the reservoir type TDS similarly contains a variety of components in liquid or semi-solid form. However the reservoir type topical delivery systems utilise a heat-sealed area to entrap the active gel between the backing membrane and a microporous membrane. Here the active ingredients are dissolved or partially suspended in a mixture of various components, including adhesives, penetration enhancers, softeners, and preservatives. It is typically manufactured using solvent, hydrogel, or hot melt-based practices.
Topically administered liquid and semi-solid drug products without a carrier device like gels, creams, lotions, foams, ointments, or sprays are not considered to be Transdermal delivery systems and are not covered by this guidance. This is even though they can be formulated to provide local, or in some cases, transdermal delivery of the drug. Hence the regulatory authority sees the need that applicants need to consult the Office of Pharmaceutical Quality early in the development process prior to pursuing a reservoir design.
Further the Transdermal and topical delivery systems are combination products as defined by 21 CFR part 3, and must comply with Current Good Manufacturing Practice (cGMP) requirements for Combination Products.
Selection of a drug substance should be justified based on the physicochemical and biological properties of the drug substance that can influence the performance of the TDS product and its manufacturability.
When qualifying the adhesives in a TDS product, an applicant should consider the attributes like for adhesive polymers as raw material, its molecular weight, polydispersity, spectroscopic analysis or infrared radiation absorption) along with thermal analysis, complex viscosity, and measurement of residual solvents, heavy metals, catalysts, and initiators need to be looked into.