Therapeutic Advances In Novel Drug Therapy

MUPIROCIN

• Antibiotic approved for topical use in humans and dogs
• Fermentation product of Pseudomonas fluorescens
• Bacteriacidal within 24-48 hours
• Mupirocin structure is different from all other known antibacterial molecules; no cross resistance with other antibiotics
• Mupirocin is not approved for use in cats; has polyethylene glycol base. Package insert (Pfizer) states product may cause nephrotoxicity if applied to large areas
• Mechanism of action is the inhibition of bacterial isoleucyl-transfer RNA synthase
• Excellent penetration of fibrous tissue found in chronic lesions (scarring)
• Active against a wide range of gram positive bacteria, including the staphylococci and most streptococci; moderately effective against gram negative bacteria. Very effective against Pasteurella multocida
• Reported antifungal activity against Candida sp, Pityrosporum ovale, and Trichophyton metagrophytes
• Pseudomonas is resistant to mupirocin
• Veterinary product is Bactoderm (Pfizer), 2% concentration
• Clinical indications: feline acne (White Vet Derm 1997), muzzle folliculitis and furunculosis, lip fold pyoderma, recurrent interdigital nodular dermatoses, pododemicosis, localized deep pyoderma (pressure point pyodermas, callus folliculitis and furunculosis, pyotraumatic folliculitis), and intertrigo
• Apply to affected areas twice daily; should not be used on mucosal surfaces or on large areas because of the potential of nephrotoxicity

PENTOXIFYLLINE

• Triple substituted methylxanthine
• Trental, 400 mg enteric coated tablet, also available in generic
• Increases erythrocyte flexibility, inhibits neutrophil adhesion to vasculature through modulation of complement 5a, increases polymorphonuclear cell chemotaxis, inhibits platelet aggregation and phosphodiesterase, suppresses tumor necrosis factor-alpha and interferon gamma
• Metabolized first in erythrocytes and then in liver
• Dosages 5-10 mg/kg TID
• Primary side effects are gastrointestinal: vomiting, diarrhea, anorexia
• May potentiate seizures
• Clinical indications (Pentoxifylline)
  • - Vasculitis
  • - Vasculopathy
  • - Contact dermatitis
  • - Atopic dermatitis
  • - Dermatomyositis
  • - Ischemic folliculopathy
  • - Pinnal vasculitis
  • - Traction alopecia
  • - Non-healing wounds, skin grafts/flaps

TERBINAFINE

• - Allylamine antifungal
• - Fungicidal against dermatophytes
• - Inhibits ergosterol synthesis by interfering with the enzyme squalene epoxidase
• - Dermatophytosis, Aspergillosis, Blastomycosis, Histoplasmosis; variable efficacy against Candida; no demonstrated efficacy against Malassezia
• - Do not need to administer with a meal
• - 250mg and 500mg pill size
• - No evidence of teratogenicity in rats/rabbits/cell cultures
• - Therapeutic plasma concentrations achieved in 10-14 days in humans & cats
• - Dosage is 7-15 mg/kg orally once daily (most cats receive ¼ of a 250 mg tablet once daily)
• - Concentrations greater than the minimum inhibitory concentration for most dermatophytes found in the skin (stratum corneum) and hair 24 hours after initiation of therapy
• - Hepatic metabolism, excreted in urine (adjust dosage for animals with hepatic/renal disease)
• - Minimal side effects (anorexia, vomiting at high dosages)
• - Lamisil, Novartis
• - 1% cream/spray for topical use (lipophilic)

CAPSAICIN

• - Neurotoxin
• - Depletes sensory C-fibers of neuropeptide content (Substance P)
• - Discomfort (burning) associated with initial use
• - Use initially (1^st 4 weeks of therapy) with a topical anesthetic (2% lidocaine viscous gel)
• Clinical indications
  • - Acral lick dermatitis
  • - Feline linear ulcerative dermatosis
  • - Neurodermatopathies
  • - Recent study (U of FL) demonstrated little promise for therapy of canine atopic dermatitis

TRIMEPRAZINE TARTRATE AND PREDNISONE

• - Temaril–P (Pfizer)
• - 5 mg trimeprazine tartrate with 2 mg of prednisone per tablet
• - Expensive for large breed dogs

INTRAVENOUS AMINO ACID THERAPY FOR SUPERFICIAL NECROLYTIC DERMATITIS

• - Aminosyn, a 10% solution, Abbott Laboratories, intravenous infusion
• - Need to use central intravenous catheter (jugular catheter) for infusion because of hyperosmolality
• - May cause transient encephalopathy; decrease the infusion rate if this occurs
• - Light sensitive - care in storage
• - 75% of patients respond within four infusions for variable amounts of time – repeat as indicated
• - Relatively inexpensive: hospitalization & catheter charges
• Clinical indications
  • - Hypoaminoacidemia in dogs with superficial necrolytic dermatitis