Chloramphenicol

Question 1

Gray baby syndrome adverse effect is produced by the following drug:

a. Tetracyclin
b. Clindamycin
c. Chloramphenicol
d. Vancomycin

Answer 1

Chloramphenicol

Question 2

Sourses ?

Answer 2

Is an antibiotic produced by streptomyces venzelae and can be chemically synthesized

Question 3

Chemically ?

Answer 3

It contains a nitrobenze ring and is aderivative of dichloracetic acid

Question 4

Spectrum ?

Answer 4

Broad spectrum

Question 5

Mode of action ?

Answer 5

Chloramphenicol acts by inhibition of protein synthesis in bacteria (and to a lesser extent in Eukaryotic cells). The inhibition is mainly by binding reversibly to the 50S Ribosomal subunit, leading to prevention of binding of the amino acid containing end of the aminoacyl t RNA to the acceptor site on the 50 S ribosomal subunt. Thus peptide bond formation is blocked. So, the action of chloramphenicol is Bacteriostatic

Question 6

Pharmacokinetics?

Answer 6

Well absorbed by oral oral route , parentral absorption is also rapid when administered in form of chloramphenicol sodium succinate . Bioavailabitity is about 70%, distribution is good and reaches all tissues including CSF , hepatically metabolized to inctive metabolite chloramphenicol glucouronide .Exeretion is mainly urinary .T 1/2 is 4 hours.

Question 7

Adverse reactions ?

Answer 7

1/Hypersensitivity reactions:-Not common, may include skin Rashes, fever, Angioedema
2/Haematologic toxicity: the most important effect is on the bone marrow. It casuses anemia, leukopenia, or thrombocytopenia ,the most dangerous effect is Aplastic anemia leading to fatal pancytopenia.
3/GIT toxicity:- nausea, vomitting ,unpleasant taste, diarrhea .
N.B :toxicity of chloramphenicol is more prominent in neonates due to delayed excretion

Question 8

Gray baby syndrome adverse effect is produced by the following drug:

a. Tetracyclin
b. Clindamycin
c. Chloramphenicol
d. Vancomyc

Answer 8

Chloramphenicol

Question 9

Antimicrobial spectrum?

Answer 9

• Salmonoella typhi
• Haemophillus
• Strep.peneumonia
• klebsella spp
• Vibrio cholera
• Entrrobacter spp
• Chlamydia spp
• Brucella
• Clostridium spp
• staphy.aureus
• pseudmonas auriginosa
• shigella spp
• Rickettsia
• Mycoplasma

Question 10

Therapeutic uses ?

Answer 10

1- Typhoid fever :- used if more safe drugs ( e.g Amoxicillin and Co-Trimoxazole )are not suffientlly effective .
Dose : 1 gram 6 hourly for 4 weeks
2- bacterial meningitis : preferred in treating meningitis caused by H.influenza .given by lumbar puncture for 2-3 day in a doseof 100 mg/ kg body weight per day
3- Anaerobic infections : especially of bowel and pelvis in dose of 250-500 mg 6 hourly for at least 4 days
4- Brucellosis : used when tetracyclines are ineffective ,in dose of 750mg - 1 gram 6 hourly for at least 4 days
5- Richettsial diseases resistant to tetracyclines.
6- Topically used for eye, ear and skin infection.