Penetration of ASM 981 in canine skin: a comparative study

Label-Free Quantification of Pharmacokinetics in Skin with Stimulated Raman Scattering Microscopy and Deep Learning

The treatment of inflammatory skin conditions relies on a deep understanding of how drugs and tissue behave and interact. Although numerous methods have been developed that aim to follow and quantify topical drug pharmacokinetics, these tools can come with limitations, assumptions, and trade-offs that do not allow for real-time tracking of drug flow and flux on the cellular level in situ. We have developed a quantitative imaging toolkit that makes use of stimulated Raman scattering microscopy and deep learning-based computational image analysis to quantify the uptake of specific drug molecules in skin without the need for labels. Analysis powered by trained convolutional neural networks precisely identified features such as cells, cell junctions, and cell types within skin to enable multifactorial analysis of skin pharmacokinetics. We imaged and quantified the flow and flux of small molecule drugs through the layers and structures of ex vivo nude mouse ear skin and extracted pharmacokinetic parameters through convolutional neural network-based image processing, including relative area under the curve accumulation, time of maximum drug concentration, and in situ partition ratios. This approach, which facilitates the direct observation and quantification of pharmacokinetics, can be used to glean mechanistic insight into underlying phenomena in skin pharmacokinetics.

Therapeutic effectiveness of calcineurin inhibitors in canine vesicular cutaneous lupus erythematosus

BACKGROUND

Oral and topical calcineurin inhibitors (CIs) have been reported to lead to complete lesion remission in several dogs with vesicular cutaneous lupus erythematosus (VCLE).

OBJECTIVES

To report retrospectively on the effectiveness and adverse effects of systemic (ciclosporin) and/or topical (tacrolimus/pimecrolimus) CIs in 11 dogs with VCLE.

METHODS

Inclusion criteria were: (i) presence of characteristic annular, polycyclic or serpiginous ulcerations distributed over the groin, axillae and/or ventral abdomen; (ii) a histopathological diagnosis of VCLE (i.e. a lymphocyte-rich interface dermatitis with vesiculation); (iii) treatment that included CIs for at least eight weeks; and (iv) follow-up until death/euthanasia or for a minimum of 12 months post-diagnosis.

RESULTS

Initial therapy included the avoidance of excessive sun exposure, oral glucocorticoids [six of 11 dogs (55%); progressively tapered over a month] and once daily ciclosporin [11 dogs (100%); median 5.8 mg/kg]. A complete remission (CR) of signs occurred between days 35 and 70 after starting CIs in eight dogs (73%); increasing ciclosporin dosage and adding topical tacrolimus induced a CR in two additional dogs (18%). Relapses were common when doses were tapered or discontinued. With the exception of three dogs that were euthanized, clinical signs were maintained in CR with oral ciclosporin (eight of eight dogs treated, 100%) or topical tacrolimus/pimecrolimus (four of eight dogs; 50%) with a median follow-up of 2.9 years.

CONCLUSIONS AND CLINICAL IMPORTANCE

These observations support CIs as the preferable therapeutic alternatives to long-term immunosuppression with oral glucocorticoids in dogs with VCLE.