Transcript SULFONAMIDES & POTENTIATED SULFAS

oAKA Sulfa drugs, enteric sulfas, systemic sulfa
oResistance is seen because of overuse
oOften potentiated to increase efficacy and make them bactericidal (otherwise Bacteriostatic)
o Trimethoprim and ormetoprim
oCommonly used sulfa drugs:
o Sulfadimethoxine (Albon, combined with ormetoprim in Primor)
o Sulfadiazine (combined with trimethoprim in Tribrissen
o Sulfamethoxazole (combined with trimethoprim in Septra- human drug)
o Sulfachlorpyridazine
o Sulfasalazine
SULFONAMIDES & POTENTIATED SULFAS
oBACTERIOSTATIC: 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.
oBroad spectrum: many G+ and G- bacteria, coccidian, and Toxopasma
oAll but sulfasalazine are well absorbed from GI tract of monogastric animals.
oLipophilic and able to cross the BBB
oMetabolized by liver, excreted by the kidneys, often used for UTIs.
MECHANISM OF ACTION and PHARMACOKINETICS
oSulfonamides are known to produce keratoconjunctivitis sicca in dogs. It is often not reversible.
oSkin reactions may be seen.
oThrombocytopenia and Leukopenia in small animals can occur.
oCrystalluria can occur which can damage renal tubules and lead to renal failure.
o Carnivores are more likely than herbivores.
o Likeliness increases if dehydrated
oOral sulfa can cause salivation in cats if tablet breaks in mouth.
PRECAUTIONS FOR USE
oClindamycin (Antirobe), lincomycin (Lincosin), pirlimycin (Pirsue)
oBacteriostatic or bactericidal by affecting protein synthesis. Action depends on concentration at infection site.
oGram +, anaerobes, and Toxoplasma
oContraindicated to use in horses, ruminants, hamsters, guinea pigs, rabbits. Can cause serious GI issues and death.
oClindamycin is often used for dental infections, deep pyodermas, accesses, bite wounds, osteomyelitis
LINCOSAMIDES
oErythromycin, azithromycin (Zithromax), tilmicosin (Micotil), tylosin (Tylan)
oTylosin and tilmicosin are primarily used in cattle.
oBacteriostatic by inhibiting protein synthesis
oExcreted in bile
oStimulates intestinal motility so cramping is common
oErythromycin can cause fatal diarrhea in horses
MACROLIDES
oAKA Flagyl
oBactericidal, possibly by effecting DNA synthesis
oEffective against protozoa, including Giardia and Trichomonas. Not very effective against aerobic bacteria. Good for
treating infections in bowel or deep wounds.
oNeurological side effects can be seen with high doses or prolonged treatment.
METRONIDAZOLE
oLow concentrations are bacteriostatic, high are bactericidal
o Disrupts protein synthesis
oCannot be used in food animals
oCan cause aplastic anemia in humans
o Avoid inhaling powder, wash hands, wear gloves
oUse with caution in cats and neonates as the liver is unable to effectively metabolize the med
oCan inhibit the metabolism of phenobarbital if given simultaneously
CHLORAMPHENICOL
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
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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