A three-year-nine-month-old uncastrated male French bulldog (13.1 kg body weight) that had developed skin pruritis came to the authors’ veterinary hospital after medication with a generic drug of ciclosporin capsule formulation for one week. Skin symptoms at the first examination were erythema, pigmentation, and alopecia in the lower jaw, and erythema on the palm or sole of every foot. Based on results of various dermatological examinations, this condition was considered probably as atopic dermatitis and pyoderma. Medication with the ciclosporin generic drug was continued for an additional three weeks. Cefalexin was administered additionally for three weeks. The pyoderma was cured, but the atopic dermatitis symptoms were not improved by these medications. The blood level (trough value) of ciclosporin was found: it was under the detection limit or 30 ng/mL. Ciclosporin was then withdrawn. A cream formulation of prednisolone was applied externally, but the symptoms worsened thereafter. Therefore, ciclosporin was re-administered to achieve a good remission with the brand-name product, which contained a microemulsion preconcentrate of the drug. Results suggest that, in some dogs, different drug designs and products with different ciclosporin formulations (microemulsion or not) exhibited different pharmacokinetics
