The activities needed for a permeation study include: bibliographic research, procurement, handling and preparation of materials and samples, test setup, material data collection, analysis, material discard, report writing and delivery. It often accounts for a significant portion of the overall expense. The expertise and experience of the personnel involved also influence the labour rate. In a simple study without validation with ex vivo membranes for 1 analyte and 1 formulation it may contribute to the 35-45% of the final price.
Most of the permeation studies require Franz cells, a thermostatic system, a chromatographic method and standard labware. Sometimes, more specialized instrumentation is necessary for the detection, as for instance, special HPLC columns or a more sophisticated gas-chromatography coupled with mass spectroscopy (GC-MS). In the latter case, the costs associated with the equipment have a significant impact on the final price. In a simple study without validation with ex vivo membranes for 1 analyte and 1 formulation it may contribute to the 20-30% of the final price. If special equipment is required it can increase its contribution up to 50-60%.
The materials involved in a permeation study or IVPT are samples and consumables. The samples refer to the product and the pure compounds used as standards, while the consumables refer to either the chemicals (solvents, acids, bases, buffers, reactants, and others) and the membranes. The cost of samples and chemicals usually has a marginal incidence on the study, while the membranes can significantly influence the final price. The membranes are the core of the whole study and can be either artificial (cheaper but less representative) or ex vivo (more expensive and more representative). Among the ex vivo membranes, the humans are more expensive than animal ones. Among animals, swine ones are the most expensive and more rappresentative. The choice of the membranes has to be driven by the goal of the study. During formula development, artificial membranes could represent a budget option. Ex vivo swine membranes better suit the requirements for product approval. Finally, IVPT studies for bioequivalence require human membranes. In a simple study without validation with ex vivo membranes for 1 analyte and 1 formulation, sample and chemicals may contribute to the 10-15% of the final price, while the membranes for a further 15-30% and in case of an IVPT up to 50%.
It refers to facilities expenses, such as laboratory fees, utilities, administrative expenses and insurances, which also contribute to the overall cost of permeation studies. These costs are often allocated as a flat rate proportional to the time the facilities are dedicated to the study. They are calculated as 5-10% of the final price.