1. SULFONAMIDES & POTENTIATED SULFAS
AKA Sulfa drugs, enteric sulfas, systemic sulfa
Resistance is seen because of overuse
Often potentiated to increase efficacy and make them bactericidal (otherwise Bacteriostatic)
Trimethoprim and ormetoprim
Commonly used sulfa drugs:
Sulfadimethoxine (Albon, combined with ormetoprim in Primor)
Sulfadiazine (combined with trimethoprim in Tribrissen
Sulfamethoxazole (combined with trimethoprim in Septra- human drug)
Sulfachlorpyridazine
Sulfasalazine
SULFONAMIDES & POTENTIATED SULFAS

2. MECHANISM OF ACTION and PHARMACOKINETICS
BACTERIOSTATIC: organisms that make their own folic acid needed for protein and nucleic acid metabolism. Sulfonamides block an enzyme needed for this process. Potentiators block different enzymes, but still those that are required for folic acid. When combined, the compound is BACTERICIDAL.
Broad spectrum: many G+ and G- bacteria, coccidian, and Toxopasma
All but sulfasalazine are well absorbed from GI tract of monogastric animals.
Lipophilic and able to cross the BBB
Metabolized by liver, excreted by the kidneys, often used for UTIs.
MECHANISM OF ACTION and PHARMACOKINETICS

3. Sulfonamides are known to produce keratoconjunctivitis sicca in dogs
Sulfonamides are known to produce keratoconjunctivitis sicca in dogs. It is often not reversible.
Skin reactions may be seen.
Thrombocytopenia and Leukopenia in small animals can occur.
Crystalluria can occur which can damage renal tubules and lead to renal failure.
Carnivores are more likely than herbivores.
Likeliness increases if dehydrated
Oral sulfa can cause salivation in cats if tablet breaks in mouth.
PRECAUTIONS FOR USE

4. Clindamycin (Antirobe), lincomycin (Lincosin), pirlimycin (Pirsue)
Bacteriostatic or bactericidal by affecting protein synthesis. Action depends on concentration at infection site.
Gram +, anaerobes, and Toxoplasma
Contraindicated to use in horses, ruminants, hamsters, guinea pigs, rabbits. Can cause serious GI issues and death.
Clindamycin is often used for dental infections, deep pyodermas, accesses, bite wounds, osteomyelitis
LINCOSAMIDES

5. Erythromycin, azithromycin (Zithromax), tilmicosin (Micotil), tylosin (Tylan)
Tylosin and tilmicosin are primarily used in cattle.
Bacteriostatic by inhibiting protein synthesis
Excreted in bile
Stimulates intestinal motility so cramping is common
Erythromycin can cause fatal diarrhea in horses
MACROLIDES

6. METRONIDAZOLE AKA Flagyl
Bactericidal, possibly by effecting DNA synthesis
Effective against protozoa, including Giardia and Trichomonas. Not very effective against aerobic bacteria. Good for treating infections in bowel or deep wounds.
Neurological side effects can be seen with high doses or prolonged treatment.
METRONIDAZOLE

7. Low concentrations are bacteriostatic, high are bactericidal
Disrupts protein synthesis
Cannot be used in food animals
Can cause aplastic anemia in humans
Avoid inhaling powder, wash hands, wear gloves
Use with caution in cats and neonates as the liver is unable to effectively metabolize the med
Can inhibit the metabolism of phenobarbital if given simultaneously
CHLORAMPHENICOL

8. GRISEOFULVIN: oral med used to treat dermatophytes (ringworm)
Known for being teratogenic in cats. Do not use in pregnant animals. Use caution when handling if pregnant.
AMPHOTERICIN B: IV med for deep or systemic infections
Rapid onset of action
Nephrotoxicity is extremely common and dose related. Monitor BUN and creatinine every time.
AZOLES: oral (ketoconazole, itraconazole, and fluconazole) or topical (miconazole, clotrimazole) meds for deep or systemic infections
Usually used before Amphotericin B because side effects are fewer
Topical meds are used for dermatophytosis, topical yeast infections
GI side effects are common with oral meds
Hepatotoxicity is an issue with ketoconazole
ALT is commonly elevated in many animals without causing concern
ANTIFUNGALS