Sulphonamides and Diaminopyrimidines

Question 1

Sulphonamides and Diaminopyrimidines: Overview

Answer 1

• bad solubility in acidic environment
• Selective to bacterial enzymes
• Bacteriostatic on their own administered together: Bactericidal

Question 2

Sulphonamides

Answer 2

• Compete with PABA for dihydropteroate SYNTHATASE
• preventing incorporation PABA into the folic acid (bacteria - need to synthesize folic acid ,mamillians can get it from food)
• worse tissue penetration
• Bacteriostatic
• Spectrum: G+ , G- , aerobic and several anaerobic
• anti-protozal: Coccidia, Toxoplasma
• resistancy is frequent: dec. penetration, PABA specific and overproduction

Question 3

Diaminopyrimidines

Answer 3

• Bacteriostatic
• inhibit THF synthesis from DHF by combining with the enzyme dihydrofolate reductase.
• G+ G- (aerobic)
• not good for anaerobes, chlamydia mycobacterium and mycolplasma.
• antiprotozoal
• plasmid resistance
• PO
• inhibited by purulent material
• good for meningitis
• kidney excretion, mainly active form
• SE: relatively non-toxic , folic acid def. in high doses

Question 4

Diaminopyrimidine combinations

Answer 4

• Bacteriocidal
• Synergistic with Sulphonamides
• less frequent resistance
• SE: Eq:fatal adverse reaction after IV administration (possible respiratory failure). *Diarrhea after PO application
• Indications: systemic infections, resp/GI , Idiopathic colitis, UTI, metritis,foot rot, prostatitis
• Special: Nocardiosism Toxoplasmisis, Coccidoisis, Sacrocystosis,Cryptosporidiosis, Chalmydiosis, Malaria

Question 5

Diaminopyrimidine drugs

Answer 5

Ormetoprim, aditoprim, baquiloprim.

*Aditoprim and Baquiloprim - hepatotoxic