CVC Highlight: Clearing it all up: A review of new dermatology drugs - Veterinary Medicine
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CVC Highlight: Clearing it all up: A review of new dermatology drugs
Are you aware of the front-line treatments dermatologists are using and investigating?


VETERINARY MEDICINE


IMMUNE-MODIFYING DRUGS

Treatment of immune-mediated skin diseases generally requires immunosuppressive drugs, such as corticosteroids. However, some medications are now available to lessen that need or to replace corticosteroids for long-term management of these conditions. While generic products for some of these medications are available, their bioavailability is not always equivalent to that of the parent product. The cost of the branded product is the most common reason why clients wish to use a generic form. It is recommended to initiate therapy with a branded product and, once full effect has been achieved, then a generic product may be used if requested by the client. The client must be informed that these generic drugs may not work as well and dosing may need to be adjusted.

Cyclosporine

Cyclosporine (Atopica—Novartis Animal Health) has both anti-inflammatory and immunosuppressive properties. It targets cell-mediated immunity, and with its other properties, it results in fewer side effects than corticosteroids. It is used to treat perianal fistulas and canine atopic dermatitis and can also be an effective maintenance drug for patients with autoimmune diseases such as pemphigus foliaceus. A double-blinded, randomized study of 29 cats comparing the efficacy of once-daily dosing of cyclosporine (1 mg/kg) to prednisolone (5 mg/kg) in cats with atopic dermatitis concluded that there was no significant difference in response.7 Atopica has just been FDA-approved as an oral solution for cats.

Given that this drug is metabolized in the liver, take caution when using it in patients with liver disease. Many other drugs use the same enzyme system in the liver, and their use can reduce the metabolism of cyclosporine. For example, giving 5 mg/kg/day ketoconazole orally can help to reduce the cyclosporine dose by up to 50%. By reducing the dose, the risk of side effects is also reduced. The most common side effects associated with cyclosporine include vomiting, diarrhea, and anorexia.

Cyclosporine is generally given without food, resulting in rapid absorption and the risk of gastrointestinal side effects. Giving with food, freezing the capsules, splitting the dose (twice daily), or giving with metoclopramide or ketoconazole, which allows a further reduction in dose, may be effective in reducing the risk of adverse effects. Long-term management requires finding the lowest effective dose, and patients should have blood work evaluated every three months during the treatment of active disease and, once stable, at least once a year.

Pentoxifylline

The human product pentoxifylline (Trental—Sanofi-Aventis) is a vasoactive agent with anti-inflammatory properties. It has been used to treat vasculitis, atopy, and dermatomyositis in dogs. It can take several weeks of treatment with pentoxifylline to be effective. One study in dogs with familial canine dermatomyositis showed a median response time to treatment of six weeks.8

This medication should be given with food, and the side effects, while rare, include vomiting, diarrhea, and central nervous system excitement.

Trilostane

Trilostane (Vetoryl—Dechra Veterinary Products) is indicated for treating Cushing's disease. This synthetic steroid analogue reduces the synthesis of cortisol, aldosterone, and adrenal androgens. This inhibition is reversible and dose-dependent. Trilostane significantly reduces the production of progesterone, so it should not be used in breeding animals.

In addition to treating Cushing's disease, trilostane has been used effectively in the treatment of alopecia X. While this is not considered a severe disease but more of a cosmetic problem, owners may elect to treat it. In one study involving 18 Pomeranians with alopecia X given a high dose of trilostane (11 mg/kg/day), 85% demonstrated improvement of clinical signs within four to eight weeks, and no adverse effects were reported.9

The clinical dose for the treatment of alopecia X ranges from 2 to 6.7 mg/kg given orally once daily with food. The recommended initial dose is 2 mg/kg given once or twice daily. Response may take several months, at which time the dose should be tapered to the lowest effective dose. Side effects are rare and can include diarrhea, vomiting, and lethargy. Patients receiving trilostane should be monitored with regular ACTH simulation tests.


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Source: VETERINARY MEDICINE,
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