Ciclosporin and the cat: Current understanding and review of clinical use

Pharmacokinetics of a single orally administered therapeutic dosage of cyclosporine A in healthy cats

This study aimed to determine a pharmacokinetic profile for a single dosage of cyclosporine A (CsA) clinically used for immunosuppression in cats. Blood-CsA-concentrations were measured before and 1, 2, 4, 6, 8, 12 and 24 h after oral administration of 7 mg/kg body weight (BW) CsA (Atopica® oral solution) to 8 healthy adult cats using high-performance liquid chromatography coupled to mass spectrometry. Pharmacokinetic parameters were calculated using WinNonLin software based on a 1-compartment-model. The median maximum plasma-concentration of 1466 ng/ml (530-2235 ng/ml; minimum-maximum) was reached after 2.0 h (1.0-4.7 h). The area under the curve was 12,568 h x ng/ml (5732-20,820 h x ng/ml) and the apparent total clearance of the drug from plasma was 557 ml/h/kg (336-1221 ml/h/kg). Half-life of absorption into the central compartment was 0.6 h (0.4-2.6 h), half-life of elimination from the central compartment was 4.6 h (1.4-7.5 h).

The Pharmacokinetic and Absolute Bioavailability of Cyclosporine (Atopica for Cats®) in Cats

This study aimed to evaluate the absolute bioavailability of cyclosporine in cats by investigating the pharmacokinetic profile after intravenous and oral administration, respectively. Twenty-four clinically healthy cats were enrolled in this study and randomly divided into four groups, namely the intravenous group (3 mg/kg), low oral group (3.5 mg/kg), medium oral group (7 mg/kg), and high oral group (14 mg/kg). Whole blood was obtained at the scheduled time points after a single dose administration and cyclosporine was determined using ultra-performance liquid chromatography-tandem mass spectrometry technology (UPLC-MS/MS). Pharmacokinetic parameters were calculated using the WinNonlin 8.3.4 software via compartmental and non-compartmental models. As a result, the bioavailability values for the low, medium, and high oral groups were 14.64%, 36.98%, and 13.53%, respectively. The nonlinear pharmacokinetic profile was observed in the range from 3.5 mg/kg to 14 mg/kg in cats following oral administration. Whole blood concentrations taken 4 h after oral administration were better correlated with the area under the blood concentration-time curve AUC_0-24 with a high regression coefficient (R² = 0.896). This concentration would be a greater predictor in the following therapeutic drug monitoring. No adverse effect was observed in the whole study process.

Pharmacokinetics and bioequivalence of two cyclosporine oral solution formulations in cats

The pharmacokinetic profiles and bioequivalence of two cyclosporine oral solutions were investigated in cats. Twenty-four cats were randomly allocated to two equally sized treatment groups in a randomized four-cycle, and dual-sequence cross-over design. Test and reference articles were orally administered in a single dose of 7 mg/kg Bodyweight. Serial blood samples were collected, and blood cyclosporine concentration was determined by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS/MS). No significant differences were present in the major pharmacokinetic parameters (Cmax, AUC0−last,) between the two formulations. The blood profiles of cyclosporine following the administration of both formulations were similar. The findings of the study suggested that the two articles were bioequivalent for cyclosporine oral solution.

Vaccination of Immunocompromised Cats

Immunocompromise is a common condition in cats, especially due to widespread infections with immunosuppressive viruses, such as feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV), but also due to chronic non-infectious diseases, such as tumours, diabetes mellitus, and chronic kidney disease, as well as treatment with immunosuppressive drugs, such as glucocorticoids, cyclosporins, or tumour chemotherapy. In this review, the European Advisory Board on Cat Diseases (ABCD), a scientifically independent board of experts in feline medicine from eleven European countries, discusses the current knowledge and rationale for vaccination of immunocompromised cats. So far, there are few data available on vaccination of immunocompromised cats, and sometimes studies produce controversial results. Thus, this guideline summarizes the available scientific studies and fills in the gaps with expert opinion, where scientific studies are missing. Ultimately, this review aims to help veterinarians with their decision-making in how best to vaccinate immunocompromised cats.

Management of Severe Oral Inflammatory Conditions in Dogs and Cats

Severe oral inflammatory disease is not uncommon in the mouths of canine and feline patients. An approach to oral diagnosis is offered. This article discusses a brief review of important points in the oral diagnosis and management of main canine (canine chronic ulcerative stomatitis (CCUS), eosinophilic stomatitis, and Wegener's granulomatosis (WG)) and feline diseases (feline gingivostomatitis/caudal stomatitis, oral eosinophilic lesions, pyogenic granuloma, and autoimmune diseases with oral manifestations), and-whereby possible-information about the current understanding of disease pathogenesis and treatment is offered.

Cytokine expression in feline allergic dermatitis and feline asthma

BACKGROUND

The pathogenesis of feline allergic dermatitis (FAD) is unclear, with several differences from allergic dermatitis in dogs and humans.

HYPOTHESIS/OBJECTIVES

To survey cytokine expression levels in healthy cats and cats affected with allergic dermatitis or asthma.

ANIMALS

Formalin-fixed, paraffin-embedded skin biopsies from 22 cats with allergic dermatitis and 21 cats without allergic dermatitis were used for cutaneous assays. Serum was obtained from 17 healthy cats, 18 cats with allergic dermatitis, and 18 cats with a presumptive diagnosis of asthma.

METHODS AND MATERIALS

Cutaneous mRNA expression was evaluated with quantitative PCR [interleukin (IL)-31 and IL-31 Receptor A] and RNA in situ hybridisation (ISH) [IL-5, IL-31, IL-31RA, IL-33 and Oncostatin M receptor (OSMR)-β]. IL-31 protein concentrations were evaluated in serum with an enzyme-linked immunosorbent assay. Serum levels of 19 additional cytokines were evaluated using a Luminex panel.

RESULTS

IL-31, IL-31RA, IL-5 and IL-33 mRNA expression were either expressed in low quantities or undetectable in most samples. By contrast, OSMR-β expression was significantly higher in the skin of allergic versus healthy cats (P < 0.0001). Although serum IL-31 was detected in a larger number of cats with allergic dermatitis than healthy cats, and concentrations appeared to be higher in cats with allergies, this difference was not statistically significant. Cats affected by asthma also exhibited insignificantly higher concentrations of IL-31 in the serum.

CONCLUSIONS AND CLINICAL RELEVANCE

Our results suggest that feline allergic diseases may exhibit different pathomechanisms from allergic diseases affecting other species. These findings are useful in guiding further therapeutic development toward targets that may have a role in the pathogenesis of feline allergic skin disease.

Cyclosporine reduces the spleen dimensions in rabbits

Purpose

To assess the influence of prolonged cyclosporine use on the macro- and microscopic morphology of the spleen.

Methods

16 adult rabbits were divided into two groups (n = 8): group 1 – a placebo group, which was followed-up over a period of nine months; group 2 – which had taken an oral dose of cyclosporine (10 mg·kg^–1·day^–1) over nine months. At the end of this period, the splenic histoarchitecture of all animals was evaluated and the splenic corpuscles were measured.

Results

The spleens of the first group presented normal characteristics and dimensions. The second group, however, had a reduction in all dimensions and its tissue texture had become soft. The white pulp and the perivascular sheath had become reduced in size and the number of lymphoid follicles had also fallen (p = 0.002), manifesting less splenic corpuscles (p = 0.0012) and lymphocyte nuclear pigments (p = 0.03).

Conclusions

Prolonged use of cyclosporine reduces the spleen size, transforming it into a soft organ associated with a decrease in white pulp, perivascular sheath, lymphoid follicles and nuclear pigments in rabbits.

Metabolism and pharmacokinetics of pharmaceuticals in cats (Felix sylvestris catus) and implications for the risk assessment of feed additives and contaminants

In animal health risk assessment, hazard characterisation of feed additives has been often using the default uncertainty factor (UF) of 100 to translate a no-observed-adverse-effect level in test species (rat, mouse, dog, rabbit) to a 'safe' level of chronic exposure in farm and companion animal species. Historically, both 10-fold factors have been further divided to include chemical-specific data in both dimensions when available. For cats (Felis Sylvestris catus), an extra default UF of 5 is applied due to the species' deficiency in particularly glucuronidation and glycine conjugation. This paper aims to assess the scientific basis and validity of the UF for inter-species differences in kinetics (4.0) and the extra UF applied for cats through a comparison of kinetic parameters between rats and cats for 30 substrates of phase I and phase II metabolism. When the parent compound undergoes glucuronidation the default factor of 4.0 is exceeded, with exceptions for zidovudine and S-carprofen. Compounds that were mainly renally excreted did not exceed the 4.0-fold default. Mixed results were obtained for chemicals which are metabolised by CYP3A in rats. When chemicals were administered intravenously the 4.0-fold default was not exceeded with the exception of clomipramine, lidocaine and alfentanil. The differences seen after oral administration might be due to differences in first-pass metabolism and bioavailability. Further work is needed to further characterise phase I, phase II enzymes and transporters in cats to support the development of databases and in silico models to support hazard characterisation of chemicals particularly for feed additives.

Clinical and histological recovery of non-thymoma-associated exfoliative dermatitis in a cat treated with ciclosporin A

CASE SUMMARY

A 6-year-old neutered female European Shorthair cat was referred for chronic, moderately pruritic, alopecic and exfoliative dermatosis that was unresponsive to antiparasitic, antibiotic or steroidal anti-inflammatory drugs. The cat presented with truncular alopecia and numerous whitish adherent scales covering the whole body. Differential diagnoses included sebaceous adenitis, dermatophytosis, demodicosis, exfoliative dermatitis associated or not with thymoma, drug reaction, feline immunodeficiency virus- or feline leukaemia virus-associated dermatoses, epitheliotropic T-cell lymphoma, and Malassezia yeasts and/or bacterial overgrowth. Blood tests were within normal limits and the retrovirus tests were negative. Skin scrapings, fungal culture, coat brushing and skin cytology were negative for parasitic or microbial elements. Radiographs showed no signs of a thymic mass. Histological examination of skin biopsies revealed marked orthokeratotic hyperkeratosis, lymphocytic (CD3+) interface dermatitis and mural folliculitis with absence of sebaceous glands and occasional apoptotic cells in different epidermal layers. Clinical and histological findings were consistent with non-thymoma-associated exfoliative dermatitis syndrome. Ciclosporin A (7 mg/kg) was administered once daily. A dramatic improvement was observed after 3 weeks. Ciclosporin A intake was then progressively spaced out as the clinical signs diminished. Skin biopsies revealed resolution of hyperkeratosis, disappearance of the inflammatory infiltrate and recovery of the sebaceous glands.

RELEVANCE AND NOVEL INFORMATION

T-cell infiltration with signs of epidermal cytotoxicity, in the absence of infectious agents or neoplastic process, suggests an immune-mediated process, and ciclosporin A, a calcineurin inhibitor, would be the drug of choice. This is the first report showing resolution of both the clinical and histological signs of non-thymoma-associated exfoliative dermatitis.

Effects of cyclosporine on feline lymphocytes activated in vitro

Cyclosporine A (CsA) is a calcineurin inhibitor that is known to decrease lymphocyte expression of NFAT-regulated cytokines in humans, dogs and cats, and thereby depress lymphocyte function. Less is known about the effects of CsA on lymphocytes in cats than in other species. Peripheral blood mononuclear cells (PBMCs) were isolated from 6 healthy cats. PBMCs were exposed to i) no treatment, ii) 5 μg/ml concavalin A (ConA), iii) 500 ng/ml CsA and iv) 5 μg/ml ConA and 500 ng/ml CsA. The effects of CsA on cell proliferation were assessed via live and necrotic cell counts from day 1 to day 6. Additionally, flow cytometry was utilized to determine the effect of CsA on apoptosis in feline lymphocytes at day 1 and day 5. ConA exposure resulted in increases in cell counts from day 1 to 6, peaking at day 5. CsA inhibited cell proliferation, indicated via decreased live lymphocyte cell counts in the cell cultures exposed to ConA and CsA, compared to the cell cultures exposed to ConA only. Furthermore, CsA induced early and late apoptotic changes in feline PBMCs. Differences in these responses may influence an individual cat's response to cyclosporine therapy.