Tape stripping, suction blister, and skin biopsy are the common methods to study dermal penetration of topical formulations, but they are usually inconvenient for the patients. On February 10th 2014, Dr. Grazia Stagni was the guest speaker at Center for Dermal Research. She is a professor of Pharmaceutics at the Arnold and Marie Schwartz College of Pharmacy, Long Island University in Brooklyn, NY. Dr. Stagni has extensive experience in cutaneous microdialysis, so she was invited to talk about skin microdialysis and its applications for topical and transdermal drug delivery. Fifteen people attended this seminar at the Life Sciences Building on the Busch Campus of Rutgers University.
Dr. Stagni began her talk by describing theoretical basis of microdialysis, which included history of its uses, different components (pump, membrane, probe, and perfusate) and their roles in the successful skin microdialysis. The techniques that she describer are simple, minimally invasive (using local anesthesia is optional). When collected, the samples are ready to be injected into HPLC.
Next, she talked about the practical issues related to uses of microdialysis in dermaceutics. Limited numbers of drug candidates is the main drawback of this technique. The reason for this is that the drug of interest must be hydrophilic enough to dissolve in the perfusate- usually an aqueous buffer- to be recovered by microdialysis. One solution to this problem is adding substances like lipids, or albumin to the perfusate. However, this approach may compromise other parameters and may add the step of purification to this technique.
In conclusion, Dr. Stagni brought some examples for application of this method. Her group was able to successfully analyze dermal concentration of acyclovir and dexamethasone, which were delivered, with the aid of iontophoresis.