Dermatologic Drugs

Topical Dermatologic Agents

Topical Antibacterials

  • Purpose: Used to prevent infection associated with minor skin abrasions and to treat susceptible skin infections.

  • Important Consideration: Can lead to drug sensitivity; therefore, documenting usage is essential.

  • Partial List of Dosage Forms:
      - Nystatin (Panalog, Animax)
      -     Bacitracin and Polymyxin (Mycitracin)
      -     Mupirocin (Bactoderm)
      -     Gentamicin (Gentacin Spray)

Antiseptics

  • Definition: Topical agents designed to kill or inhibit the growth of microorganisms on living tissue.

  • Important Notes:
      - Each antiseptic exhibits its own spectrum of activity, dilution values, and specific application instructions. It is critical to read labels before use.
      - Classified as:
        - Bactericidal: Kills bacteria.
        - Virucidal: Kills viruses.
        - Fungicidal: Kills fungi.
        - Sporicidal: Kills spores.

  • Dilution Instructions: When diluting any antiseptic, always begin with the quantity of water and then add the chemical to avoid splashing chemicals into the eyes.

Iodine Compounds

  • Type: Iodophores

  • Examples:
      - Betadine®
      -     Povidine®

  • Properties:
      - Moderately to highly bactericidal & fungicidal, and highly virucidal.
      - Used frequently for presurgical scrubs. Do minimum of three scrubs
      - Known to be corrosive to various surfaces and causes staining.

Biguanide

  • Example: Chlorhexidine (Nolvasan®, Hibiclens®, Virosan)

  • Applications:
      - Effective for skin wounds.
      - Commonly used as a presurgical scrub and in oral cleansing solutions.

  • Characteristics:
      - Provides residual action.
      - Highly bactericidal, moderately virucidal, and poorly fungicidal.

Alcohols

  • Example: 70% Isopropyl Alcohol.

  • Efficacy:
      - Highly bactericidal.
      - Some virucidal action.
      - Exhibits poor fungicidal properties.

  • Limitations: Affected by the presence of organic material and dirt.

Malassezia Yeast

  • General Information:
      - Malassezia spp. are associated with yeast infections in small animals.
      - Causes skin and ear infections in affected animals.

  • Pododermatitis - thrush - bacterial infection horse hoof

Dermatophytosis (Ringworm)

  • Causative Agents: Microsporum canis and others (zoonotic form).

  • Conditions: Characterized by skin infections, notably referred to as "ringworm."

  • Visual Reference: Figure 14.1 illustrates circular areas of alopecia due to Microsporum canis infection affecting hair integrity.

Topical Antifungals

  • Condition Treated: Thrush in horses.

  • Examples of Dosage Forms:
      - Panalog®
      -     Kopertox®
      -     Clotrimazole cream (generic)
      -     Tresaderm®

Topical Antiseborrheics

  • Purpose: Treatment for seborrhea. Dry, dandruff skin

  • Dosage Forms for Seborrhea Sicca:
      - Sulfur (SebaLyt shampoo, Allerseb T)
      - Salicylic Acid (SebaLyt shampoo, KeraSolv gel) - effective for hyperkeratosis.
      - Coal Tar (Lytar shampoo, Mycodex Tar and Sulfur shampoo) - caution: stains light haircoats, toxic to cats.

  • Dosage Forms for Seborrhea Oleosa:
      - Benzoyl Peroxide (Pyoben gel, OxyDex) - useful for treating acute moist dermatitis ("hot spots", superficial pyoderma).
      - Selenium Sulfide (Seleen Plus shampoo, Selsun Blue shampoo).

Topical Antipruritics

  • Definition of Pruritis: Pruritis refers to itching.

  • Function: Topical antipruritics provide temporary or mild relief from itching.

  • Dosage Forms:
      - Topical Anesthetics: Ingredients ending in –aine; examples include Xylocaine, ResiPROX.
      - Soothing Agents: Oatmeal-containing products (Epi-Sooth, Oatderm shampoos).
      - Antihistamines: Available in formulations like Histacalm shampoo and spray.
      - Corticosteroids: Included in products like Gentocin Spray, Vetalog Cream, Panolog Cream.

Fatty Acid Supplements

  • Role: Contributes to the smooth texture and luster of the coat and has anti-inflammatory effects against pruritis.

  • Types: Include omega-3 and omega-6 fatty acids.

  • Essential Fatty Acids:
      - Linoleic Acid (omega-6) and Linolenic Acid (omega-3) are not synthesized in dogs.
      - Arachidonic Acid cannot be synthesized in cats and is essential for their health.

  • Health Benefits: May provide support in conditions such as heart disease, cancer, autoimmune diseases, and rheumatoid arthritis.

Selective Immunosuppressors

  • Application: Used for treatment of atopy. - Seasonal allergies

  • Dosage Form: Cyclosporine (Atopica®).

  • Side Effects: Vomiting, commonly resolves with continued use.

Apoquel®

  • Active Ingredient: Oclacitinib.

  • Mechanism: Inhibits JAK 1 and JAK 3 receptors, targeting cytokines responsible for pruritis and inflammation.

  • Indication: Used for atopic dermatitis in dogs.

Zenrelia®

  • Active Ingredient: Ilunocitinib.

  • Mechanism: Inhibits JAK 1 and JAK 2 receptors, also targeting cytokines involved in pruritis and inflammation.

  • Indication: Indicated for atopic dermatitis in dogs.

CADI

  • Full Form: Canine Atopic Dermatitis Immunotherapeutic.

    • Cytopoint

  • Mechanism: Involves a caninized anti-cIL-31 monoclonal antibody targeting canine IL-31 cytokine.

  • Function: IL-31 sends "itch" signals to the brain.

  • Administration: Injectable subcutaneously once a month for dogs only.

Topical Antiparasitics

  • Note: Detailed discussion is reserved for the anti-parasitic lecture.