4 - Sulfonamide, Trimetoprim, Quinolones, Nitrofurantion, and Miscellaneous Antibiotics

Question 1

sulfonamides class of drug has been used as…

Answer 1

as antibiotic, as diuretic and to lower blood glucose

Question 2

In terms of chemical properties they are relatively weak acidic hence have limited solubility in water, therefore they can be more soluble in…

Answer 2

alkaline conditions

Question 3

what is the moa of sulfonamides?

Answer 3

sulfonamide could compete with PABA to be converted into the dihydrofolic acid (due to structure similarity); so instead of the enzyme dihydropteroate synthase convert PABA into dihydrofolic acid, the enzyme actually binds to sulfonamides

Question 4

Sulfonamide is often combined with trimethoprim or pyrimethamine to produce…

Answer 4

synergistic activity

Question 5

one unique properties of sulfonamides is..

Answer 5

when sulfonamides are used against Rickettsiae, it can stimulate the growth of Rickettsiae instead of inhibiting it

Question 6

3 major groups classification of sulfonamides:

Answer 6

Oral absorbable, Oral non absorbable and Topical

Question 7

what is the main differences between Trimethoprim and pyrimethamine?

Answer 7

Trimethoprim has activity against bacteria while pyrimethamine has activity against protozoa

Question 8

what is the moa of Trimethoprim?

Answer 8

selectively inhibits bacterial dihydrofolic acid reductase (DHFR)

Question 9

why the antibacterial activity of trimethoprim in prostatic and vaginal fluids is higher?

Answer 9

in vaginal area the pH is usually more acidic while the properties of trimethoprim itself has basic properties hence it can accumulate in vaginal area

Question 10

First quinolone discovered is called…

Answer 10

nalidixic acid

Question 11

what is the moa of fluoroquinolones?

Answer 11

1. the fluoroquinolone inhibit the DNA gyrase and prevents prevents the relaxation of positively supercoiled DNA that is required for normal transcription and replication
2. the fluoroquinolones also inhibit the topoisomerase IV that interferes with separation of replicated chromosomal DNA into the respective daughter cells during cell division (so topoisomerase IV can actually help in the separation of replicated DNA)

Question 12

the classification of Fluoroquinolones is based on…

Answer 12

the antibacterial activity and the pharmacokinetics properties

Question 13

Most fluoroquinolones are eliminated by renal mechanisms and there is one that is excreted via non-renal renal mechanism which is…

Answer 13

moxifloxacin

Question 14

Nitrofurantoin is used as …

Answer 14

Second-line of agent for the prevention and treatment of UTI

Question 15

classification of Miscellaneous antibiotics based on the action are…

Answer 15

those that act on cell on synthesis and those that disrupt cell membrane structure

Question 16

vancomycin is used for…

Answer 16

Used to treat infection against bacteria that has already develop resistance to other antibiotics

Question 17

what is the moa of vancomycin?

Answer 17

as their main action is to inhibit cell wall synthesis, the moa is via binding to dipeptide D-alanyl-Dalanine terminus of nascent peptidoglycan, thereby inhibits transglycosylase, preventing further elongation of peptidoglycan and cross-linking

Question 18

what is the moa of fosfomycin?

Answer 18

fosfomycin need to be transported into the bacterial cell by glycerophosphate or glucose 6-phosphate transport systems and once it is inside the bacteria the fosfomycin Inhibits the cytoplasmic enzyme enolpyruvate transferase (MurA) by covalently binding to the cysteine residue of the active site thereby blocking the addition of phosphoenolpyruvate to UDP-N Acetylglucosamine (precursor of N -acetylmuramic acid)