Comparison of high performance liquid chromatography and immunoassay methods for measurement of cyclosporine A blood concentrations after feline kidney transplantation

Effects of multiple oral dosing of itraconazole on the pharmacokinetics of cyclosporine in cats

Itraconazole (Icz) has been known to increase the cyclosporine (CsA) trough level in human transplant patients. However, the interaction of Icz with CsA has not been reported in cats. In this study, the effect of multiple dosing of Icz on the pharmacokinetics of CsA in three healthy cats was investigated. The treatments included CsA 5mg/kg alone and CsA 5mg/kg+multiple-dose of Icz 10mg/kg. Co-administration of Icz with CsA resulted in significant increases of oral bioavailability of CsA. The results of our study suggest that administration of multiple therapeutic doses of Icz may decrease the required CsA dosage in CsA-based immunosuppressive therapy used for renal transplantation in cats.

Use of Capecitabine to Prevent Acute Renal Allograft Rejection in Dog Erythrocyte Antigen-Mismatched Mongrel Dogs

OBJECTIVE

To assess efficacy and toxicity of a capecitabine (CAP)-based regimen for preventing rejection of renal allografts in dog erythrocyte antigen (DEA)-mismatched mongrel dogs.

STUDY DESIGN

Prospective, pilot study.

ANIMALS

Eight healthy, unrelated, DEA mismatched, adult mongrel dogs.

METHODS

All dogs received CAP, starting at 50 mg/m2 PO b.i.d. 4 days preoperatively, increasing to 200 mg/m2 PO b.i.d. by the day of surgery. All dogs received cyclosporine-A (CsA) and prednisolone starting 2 days preoperatively. Standard heterotopic renal transplantation with native nephrectomy was performed. After 90 days, surviving dogs were euthanatized and histopathologic examination was performed.

RESULTS

Two of 8 dogs developed acute neurotoxicity leading to death or euthanasia within 5 days of surgery. For the 6 remaining dogs, there were no statistically significant changes in complete blood count or serum biochemical values. No opportunistic infections developed during the study period. Five of 6 dogs had no to minimal evidence of graft rejection. Two of 6 dogs developed superficial and pigmentary keratitis. Significant histopathologic findings in all dogs included mild lymphoplasmacytic gastroenteritis, steroid hepatopathy, and corneal epithelial thinning. One dog had moderate interstitial nephritis and pyelitis.

CONCLUSIONS

In this experimental model, a CAP-CsA-prednisolone immunosuppressive regimen was effective in preventing rejection of allografts in DEA-mismatched dogs. Severe, unpredictable neurotoxicity and variable ocular toxicity significantly limit clinical applications at this time.

CLINICAL RELEVANCE

A CAP-CsA-prednisolone protocol is an effective, oral immunosuppressive regimen for prevention of allograft rejection in DEA-mismatched mongrel dogs. For clinical application, identification of patients susceptible to toxic side effects would be necessary.

Evaluation of the Effect of Two Dose Rates of Cyclosporine on the Severity of Perianal Fistulae Lesions and Associated Clinical Signs in Dogs

OBJECTIVE

To investigate the effect of cyclosporine (2 or 5 mg/kg every 24 hours) on perianal fistulae (PAF) lesions.

STUDY DESIGN

Blinded randomized, prospective trial.

ANIMALS

Dogs (n = 20) with perianal fistulae.

METHODS

Dogs were randomly assigned to administration of either 2 mg/kg (n = 10) or 5 mg/kg (n=10) of cyclosporine orally every 24 hours for 8 weeks. Lesion surface area was measured, lesion severity was graded using a visual analog scale, and the presence and severity of clinical signs recorded every 2 weeks.

RESULTS

Lesion variables were significantly reduced in both groups after 8 weeks and owners also reported a reduction in clinical sign severity. The 5 mg/kg dose rate significantly accelerated lesion resolution compared with 2 mg/kg. In the 2 mg/kg group, 20% of dogs had complete resolution of clinical signs and 10% had resolution of lesions. In the 5 mg/kg group, 40% of dogs had complete resolution of clinical signs and 60% had resolution of lesions.

CONCLUSIONS

A dose rate of 5 mg/kg every 24 hours was more effective at reducing the surface area and severity of PAF lesions than 2 mg/kg every 24 hours but less effective at resolving PAF lesions than previous studies using dose rates > or =5 mg/kg every 12 hours.

CLINICAL RELEVANCE

Cyclosporine at 5 mg/kg every 24 hours may be useful for the palliation of PAF lesions.

Evaluation of once daily treatment with cyclosporine for anal furunculosis in dogs

Twenty-four dogs with anal furunculosis were treated with cyclosporine once daily for 13 weeks at dosages of 1.5, 3.0, 5.0 or 7.5 mg/kg, and re-examined after six and 12 months. After 13 weeks the disease in six of the dogs was in remission, 11 were controlled or improved and seven had failed to respond. The response of the dogs given the highest dose was significantly better than the response of the other groups taken together (P < 0.014), and better than the responses of the groups given 1.5 mg/kg and 5 mg/kg (P < 0.05). The dogs improved clinically during the treatment, most rapidly during the first five weeks. Of the six dogs that were in remission after 13 weeks, three relapsed after one, two and six months. The 11 dogs that were improved or controlled after 13 weeks were either left untreated or were continued on cyclosporine medication for one to three months at a dosage of 1.5 to 7.5 mg/kg; the disease went into remission in four cases and remained controlled in the other seven, but four of the 11 cases relapsed during the 12 months following the treatment. The side effects observed included increased coat turnover and transient vomiting.

Cyclosporin and ketoconazole interaction for treatment of perianal fistulas in the dog

OBJECTIVE

To assess the use of concurrent ketoconazole and low dose cyclosporin administration in a group of dogs with clinical evidence of perianal fistulas, and to determine if this combination could be used to manage perianal fistulas effectively.

DESIGN

Prospective clinical trial

PROCEDURE

Sixteen dogs with clinical evidence of perianal fistulas were given ketoconazole (10 mg/kg once daily) and cyclosporin (1 mg/kg twice daily initially) for 16 weeks. Blood cyclosporin assays were performed regularly and cyclosporin doses were altered to achieve a stable blood level above 200 ng/mL. Regular examinations assessed the dogs' general health, changes in clinical behaviour, fistula size and number. A complete blood count and serum biochemical analysis was performed in all dogs before and after the treatment period, and after 8 weeks of treatment in 12 dogs. Dogs were assessed for recurrence of lesions at 1, 3 and 12 months after the trial.

RESULTS

All dogs showed marked improvement in lesions and behaviour within 14 days of the medication. Fourteen dogs completed the trial. Two dogs were excluded due to concurrent disease. Thirteen dogs (93%) showed complete resolution of fistulas during the treatment period. Seven dogs (50%) had no recurrence after 12 months. Recurrence was seen in three dogs (21%) at 8, 10 and 12 months after treatment, and in three dogs (21%) within 1 month of treatment. The medication was well tolerated. Side effects included transient anorexia, vomiting and lethargy in some dogs, increased shedding of hair and gingival hyperplasia. Ketoconazole administration allowed a dramatic reduction in cyclosporin dose (over 90% in 12 dogs and 80% in the other two) compared to previously reported cases treated with cyclosporin alone.

CONCLUSION

The use of combined ketoconazole and cyclosporin provided an effective treatment for perianal fistulas. Outcomes were similar to those seen with cyclosporin alone, but allowed a significant reduction in cyclosporin dose and, therefore, cost. The use of immunosuppressive therapy in the treatment of perianal fistulas was effective and avoided many of the problems associated with surgical treament.