Sulfonamides

Question 1

MOA?

Answer 1

Inhibits folic acid synthesis by binding to the active site of dihydropteroate synthetase in the place of PABA

Question 2

Bacteriocidal or bacteriostatic?

Answer 2

Bacteriocidal

Question 3

What is it usually potentiated with?

Answer 3

Trimethoprim or ormetrprim

Question 4

What bacterial is it used against?

Answer 4

G(+) and G(-)

Variable with Pseudomonas, nocardia, chlamydia, some protozoa (coccidia, toxoplasma)

Question 5

What isnt it very useful against?

Answer 5

Anaerobes

Question 6

Indications for use?

Answer 6

RTI (horses), UTI, wound infections/foot-rot, soft tissue infections (pyodermas), protozoal infections (toxoplasmosis, coccidiosis and equine protozoal myeloencephalitis)

Question 7

Resistance?

Answer 7

Stap, corynebacterium, Bacteriodes, Enterococcus, Pseudomonas

Question 8

Describe Absorption, Distribution and Excretion?

Answer 8

A - more soluble in alkaline pH, oral and topical are well absorbed –> variable oral absorption in horses and ruminants
D - most body tissues and fluids (CNS, CSF, pleural and synovial prostate) lipophilic
E - metabolised primarily hepatic oxidation and conjugation and excretion is renal

Question 9

Adverse effects?

Answer 9

Crystalluria (dogs) NaCO3
Keratoconjuntivitis sicca (dry eye)
Hypersensitivity (type 3): idiopathic
Haematopoietic toxicity seen with Sulfaquinoxaline due to inhibition of Vit K epoxide reductase and thrombocytopenia 
Thyroid metabolism disorders 
Diarrhoea in horses following oral admin
Carcinogenesis

Question 10

Name some drugs?

Answer 10

Sulfamethoxine

Sulfamethoxazole