When is nitrofurantoin most effective?
What specific organisms tend to be highly resistant to sulfa drugs? (5)
Therapeutic Use - Sulfadimethoxine
More soluble + less toxic
How are sulfa drugs excreted from the body?
renal excretion of unchanged drugs + metabolites
Via glomerular filtration + active secretion + passive tubular reaborption
Therapeutic use - Orbifloxacin + Marbofloxacin
Dermal + Respiratory + Urinary infections - dogs and cats
Why are sulfonamides safe for mammals?
Mammals require formed folic acid and do not require synthesis of it.
How are fluoroquinolones distributed throughout the body?
Including CNS, bone, and prostate
Therapeutic use - Danofloxacin
Bovine respiratory infections
What are the sulfoamides derivitives of?
Produced by substitution of the amino group
What are the side effects of trimethoprim or ormetoprim?
Decrease in plasma levels of thyroid hormones
Why is rifampin combined with erythromycin?
Treatment of rhodococcus equi infections in foals
What are the three sulfonamide mixtures that are used?
Sulfadiazine + trimethoprim
Sulfamethoxazole + trimetoprim
Sulfadimethoxine + ormetoprim
What are the side effects seen with sulfa drugs?
Hypoprothrombinemia + Thrombocytopenia
Reduced sperm counts
Therapeutic use - Orbifloxacin only
Gram (-) infections in horses
What is the specific mechanism of action for fluoroquinolones?
Inhibit bacterial DNA gyrase + topoisomerase enzymes that control DNA supercoiling
How do sulfa drugs cause renal crystalluria?
Precipitaion of sulfonamides in neutral or acidic urine
Occurs more often with large or prolonged doses w/ inadequate water intake
How is nitrofurantonin used?
lower urinary tract infections in dogs and cats
What are the three other drugs that interfere with nucleic acid synthesis but do not belong to a group?
Therapeutic use - Enrofloxacin
Dermal + respiratory + urinary infections
Dogs - cats - brids
(only respiratory infections in cattle)
What can metronidazole be combined with? Why?
Prevent pseudomembranous colitis
What protozoas does metronidazole act against?
What does enrofloxacin work for in regards to bovine respiratory disease?
How is rifampin distributed throughout the body?
Wide distribution to cells and tissues
How is rifampin excreted?
Primarily in the bile
up to 30% can be excreted in the urine
Parent drug can also be excreted
How are potentiated sulfa drugs handled in the body?
Transcellular fluid = 80% of plasma concentration
Bind to albulmin
How is rifampin adminstered?
Foals + Dogs + Cats
What adverse effects are seen with fluoroquinolone use?
Reversible erosion of articular cartilage in dogs and foals
Retinal degeneration in cats
What is the protocol for Enrofloxacin use in cattle?
Can be given for up to 5 days in cattle
Single high dose for respiratory infections
What type of inhibtion does sulfa drugs cause with PABA?
What are the adverse effects of rifampin?
Hepatotoxicity with pre-existing liver disease
Re-oranged colored urine, sweat, and saliva but not harmful
How two drugs can be mixed with sulfa drugs to make potentiated sulfonamides?
What is the specific mechanism of rifampin?
Inhibits DNA-dependent RNA polymerase
Prevents initiation of RNA synthesis
What happens with elmination rate with rifampin after repeated doses? why?
induces microsomal enzymes
What happens to the bacteria if folic acid is decreased?
Cannot multiply, grow, and survive
How does elimination of the parent drug and metabolite differ with rifampin?
Parent drug is reabsorbed in the gut while the metabolite is not
How can nitrofurantoin be adminstered?
Water-soluble wound dressing
What do potentiated sulfa drugs allow for?
Sequential blockade of folate synthesis
How is sulfasalazine processed in the gut?
Cleaved into sulfapyridine + 5-ASA via the gut bacteria
How are fluoroquinoles metabolized?
Where do potentiated sulfa drugs tend to concentrate in the body?
Prostate, making it a good therapy for praostatitis
What is different about sulfa drug metabolism in dogs?
There is no acetylation
What type of bacteria tend to be resistant to fluoroquinolones?
What type of respiratory infections in cattle does danofloxacin work for?
What breed of dog is most susceptible to arthritis from sulfa drugs? what is the most common drug that causes this?
Therapeutic Use - Sulfasalazine
Enteric sulfa drug
Colitis + IBD in dogs and cats
How does resistance against fluoroquinolones occur?
How are fluoroquinolones excreted?
Parent drug (15 to 50%)
and metabolites excreted in bile and urine
Why is rifampin combined with antifungal agents?
Treat fungal infections like aspergillous or histoplasmosis in dogs and cats with CNS infections
Therapeutic Use - Sulfamethazine
Cattle + Sheep + Swine
What so the metabolites of sulfasalazine do?
Sulfapyridine = antibacterial agent
5-ASA = anti-inflammatory
How is the Rifampin metabolized?
Metabolite is antibacterial as well
What is the structure of sulfasalazine?
Linked to a molecule of 5-ASA
What is PABA important for?
Intergral part of folic acid synthesis
What is the use of metronidazole?
Dogs, horse, + cats = severe infections caused by anaerobic pathogens
most importantly - brain abcesses + pelvic/genitourinary tract/respiratory infections
When are sulfoamides bactericidial?
Urinary tract infections due to the fact that the drug concentrates there and reaches high enough levels
Therapeutic Use - Sulfachlorpyridazine
Rapidly absorbed + excreted
Orally in Cattle under 1m
Swine - respiratory + enteric infections (colibacillosis)
How is nitrofurantoin processed in the body?
Reduced by bacteria to reactive intermediates that inhibit nucleic acid synthesis
What is the specific mechanism of action for metronidazole?
Anaerobic bacteria + protozoa takes up drug
Reduces to cytotoxic metabolite = DNA disruption
How are potentiated sulfa drugs adminstered?
How are potentiated sulfa drugs metabolized in the body?
Via actylation + glucuronide conjugation
What organism is metronidazole most bactericidal against?
What is Rifampin bactericidal against?
Gram + pathogens
What adverse effects are seen with Enrofloxacin specifically?
Seizures in dogs who are on phenobarbital
What groups of bacteria do sulfa drugs kill?
Gram positive and negative
What is folic acid important for?
Purine + DNA synthesis
What are the three groups of drugs that interfere with nucleic acid synthesis?
Therapeutic use - Difloxacin
Dermal + Respiratory + Urinary infections in dogs
Therapeutic Use - Sulfacetamide
Only one prepared as a salt at neutral pH
What is the protocol for Nitrofurantoin use in food-producing animals?
What is important so that sulfonamides have antibacterial action?
Free para-amino group is essenstial
What does enrofloxacin work for in regards to swine respiratory disease?
What are the upsides to using potentiated sulfonamides?
Reduced rate of resistance
What is the protocol for fluoroquinolone use in food animals?
Extra label use is not allowed
How is danofloxacin used?
Single dose or twice 48 hours apart
What specific organisms are highly sensitive to sulfa drugs? (8)