sulphonamides, cotrimoxazole , quinoles and nitromidazoles

Question 1

Brief about history and classification of sulphonamides

Answer 1

first used against streptococcal septicaemia
very first anti microbial agents
classification - short-acting - sulfadiazine
intermediate-acting sulfamethoxazole
long-acting sulfadoxine
special purpose - sulfacetamide

Question 2

Brief about the antibacterial spectrum and resistance to sulfonamides

Answer 2

sensitive ones are haemophilus influenzae vibrio cholerae
resistance is devolped by 3 mechanisims in whic organisms
Adopt a different pathway of folate synthesis
Folate synthetase enzyme has lower affinity for sulfonamides
increased amounts of PABA is produced
resistant organisms are meningococci gonococci
stph. aureus , strep . pyogenes

Question 3

Brief about pharmacokinetics of sulfonamides

Answer 3

Rapidly absorbed from the git
the highly protein bounded are long acting the free for of sulfadiazine takes up same conc in plasma and CSF
metabolism basically occurs in the liver by acetylation of n4 nitrogen by a non microsomal enzyme
the acetylated derivative is very less soluble in acidic urine and the parent drug may cause crystalluria.
excreted by both glomerular filtration and renal secretion and reabsorption

Question 4

enlist adverse effects and drug interactions of sulfonamides

Answer 4

nausea, vomiting, and epigastric pain
crystalluria is dose-related can be minimized by administration of alkalized fluid in order to dissolve the acetylated derivative
hepatitis in 1 percent of patients
topical administration is not advised due to contact sensitization
ocular use is permitted
cause haemolysis in a dose dependent manner
interactions; interfere with metabolism of tolbuamide, and warfarin
thus enhancing their action
displace methotrexate from binding , decreasing its renal secretion
causing toxicity.

Question 5

uses of sulfonamide

Answer 5

used in combination with sulphonamide and trimethoprim
second drug of choice for lymphogranuloma
suppressive therapy of urinary tract infection, pharyngitis
ocular sulfacetamide is a cheap alternative in conjunctivitis
but an additional azithromycin and tetracyclin therapy maybe required

Question 6

antibacterial spectrum of cotrimoxazole

Answer 6

Bacteria sensitive are : salmonella typhi
pneumocystis carinii 
Yersinia
Enterobacter
klebsiella 
sulfonamide resistant strains of shigella,
 haeumophilus infulenzae 
strep. pyogenes 
staph aureus

Question 7

brief the pharmacokinetics of cotrimoxazole

Answer 7

trimethoprim is generally combined with sulphamethoxazole
due to same half life ( 10 hrs) in a ratio of 20:1
trimethoprim easily crosses the blood brain barrier
trimethoprim metabolized in the liver excreted in the urine

Question 8

enlist adverse effects of cotrimoxazole

Answer 8

Nausea, vomiting headache, stomatitis and rashes.
marginal folate levels patients might develop megaloblastic anaemia
Not to be given during pregnancy high teratogenic risk
casuses neonatal haemolysis and methemoglobinemia
elderly at rsk of bone marrow toxicity
high incidence of bone marrow hypoplasia among AIDS patients
infected with pnemocysytis carinii
diuretics given with cotrimoxazole cause thrombocytopenia

Question 9

uses of cotrimoxazole

Answer 9

Tonislitis ,pharyngitis, sinusitis, otitis media, chronic bronchitis
pnemocystis carinii infection in aids patients

Question 10

brief about antibacterial spectrum of fluoroquinolones