PHARMACO - Chloramphenicol Flashcards
?S ribosomes in bacteria
70
?S ribosomes in mammalians
80
Basis for selective toxicity against microorganisms without causing major effects on mammalian cells
3 Differences
Ribosomal subunits
Chemical composition
Functional specificities of component nucleic acids and proteins
General MoA
Bactericidal
General binding at what ribosome
50S except for tetracycline
Inhibits transpeptidation (catalyzed by peptidyl transferase)
chloramphenicol
Blocks the binding of aminoacyl moiety of tRNA to mRNA complex so the peptide at the donor site cannot be transferred to the amino acid acceptor
chloramphenicol
Bind at 50S-block translocation of peptidyl-tRNA from the acceptor site to the donor site
Macrolides, telithromycin, and clindamycin
Bind to 30S
Tetracyclines
Blocks the binding of amino-acid-charged tRNA to the acceptor site
Tetracyclines
Constrict the exit channel on the ribosome through which polypeptides are extruded tRNA synthase activity is inhibited
Streptogramins
inhibits tRNA synthase activity
Streptogramins
bactericidal AB which bind to the 50S
Streptogramins
Bacteriostatic
Binds to a unique site at 50S
Blocks formation of tRNA-ribosome-mRNA complex
Linezolid
Broad spectrum
chloramphenicol
tetracycline
moderate spectrum
macrolides
ketolides
narrow spectrum
lincosamides
streptogramins
linezolid
newer antibiotics
streptogramins
linezolid
Are there other antimicrobial drugs in chloramphenicol class
No
RoA of Chloramphenicol
Oral as well as parenteral
Tissue distribution of Chloramphenicol
Distributed throughout all tissues
Crosses placental and blood-brain barriers
Chloramphenicol
Undergoes enterohepatic cycling
Chloramphenicol
tetracycline
Enzyme that inactivates chloramphenicol
hepatic glucoronosyltransferase
Does Chloramphenicol undergo enterohepatic cycling
Yes
Fraction excreted in urine unchanged or changed in chloramphenicol?
unchanged
MoA of Chloramphenicol
Bacteriostatic
When does Chloramphenicol become bactericidal
H. influenzae
N. meningitidis
Bacteroides
Is chloramphenicol effective for chlamydia
No
Resistance to chloramphenicol
Plasmid mediated-formation of acetyl- transferases that inactivate the drug
chloramphenicol is Rarely used as a systemic drug because
of its toxicity
Backup drug for severe infections caused by salmonella
chloramphenicol
Treatment of pneumococcal and meningococcal meningitis in beta-lactam-sensitive persons
chloramphenicol
Commonly used as topical agent
chloramphenicol
Sometimes used for ricketssial infections
Infections caused by anaerobes like B. fragilis
chloramphenicol
GI disturbances occur from
direct irritation and superinfection which may lead to candidiasis
toxicity of chloramphenicol in the bone marrow
Inhibition of red cell maturation-decrease in circulating RBC
Dose dependent and reversible
toxicity of chloramphenicol
Rare idiosyncratic reaction
Irreversible and maybe fatal
aplastic anemia
toxicity of chloramphenicol
Premature infants
Deficiency of hepatic glucoronyltransferase
Tolerated in older infants
Decreased RBC, cyanosis and cardiovascular collapse
gray baby syndrom
enzyme only present in mature liver
hepatic glucoronosyltransferase
disease in which all formed elements decrease in level
caused by chloramphenicol
pancytopenia
prototype drug of tetracycline
tetracycline
drug that must be taken before meals as its absorption is impaired by food and multivalent cation
tetracycline
tissue distribution of tetracyclines (narrow or wide)
wide
crosses the placental barrier
tetracycline
contraindicated in pregnancy because it crosses the placental barrier
tetracycline and chloramphenicol
mode of elimination
urine except for ____
All tetracycline drugs eliminated in the urine except for
Doxycycline
tetracyline drugs with longer half lives
doxycycline and minocycline
what kinds of bacteria do tetracyclines cover
gram (+) and gram (-)
type of resistance to tetracyline (2)
Plasmid-mediated resistance is widespread
Decrease activity of the uptake systems
Development of efflux pumps for active extrusion of the drug
drug of choice for vibrio cholera
tetracycline
Alternative drug for syphilis
Respiratory infections caused by susceptible organisms
tetracycline
Treatment of acne
tetracycline
most common tetracycline used for the treatment of acne
doxycycline
antibiotic for Leptospirosis
tetracycline/doxycycline
Prophylaxis against chronic bronchitis
tetracycline
Prophylaxis against malaria
tetracycline
Selective uses
Gastrointestinal ulcers caused by H. pylori
Tetracycline
Selective uses
Lyme disease
Doxycycline
Selective uses
Meningococcal carrier state
Minocycline
Selective uses
Prevention of malaria
Treatment of amoebiasis
Doxycycline
Selective uses
ADH-secreting tumors
Inhibits renal actions of ADH
Demeclocycline
Identify which drug has this toxicity TOXICITY 1. GI disturbances Mild nausea and diarrhea to severe, possibly life-threatening colitis Disturbances in the normal flora Candidiasis (oral and vaginal) Bacterial superinfection S. aureus or C. difficile Rare
tetracyclines
Identify which drug has this toxicity 2. Bony structures and teeth Fetal exposure Tooth enamel dysplasia Irregularities in bone growth Contraindicated in pregnancy Younger children (under age 8) Enamel dysplasia and crown deformation when permanent teeth appears Bind with calcium and deposit in newly formed bones (impaired long bone formation ) and teeth (discolouration of teeth)
tetracyclines
Identify which drug has this toxicity
3. Hepatic toxicity
High doses in pregnant women and those with preexisting renal disease may impair liver function
Hepatic necrosis
tetracyclines
Identify which drug has this toxicity
Hepatic toxicity - Hepatic necrosis
tetracyclines
Identify which drug has this toxicity 4. Renal toxicity Fanconi’s syndrome Renal tubular acidosis Intake of outdated tetracycline
tetracyclines
Identify which drug has this toxicity
4. Vestibular toxicity
Doxycycline and minocycline
Dose-dependent reversible dizziness and vertigo
tetracyclines
- Photosensitivity
Demeclocycline
Enhanced skin sensitivity to ultraviolet light
tetracyclines
Rare GI disturbance caused by tetracycline
bacterial superinfection
GI disturbance caused by tetracycline
Mild nausea and diarrhea to severe, possibly life-threatening colitis
Disturbances in the normal flora
Candidiasis (oral and vaginal)
Bacterial superinfection
Toxicity in Bony structures and teeth caused by tetracycline
- Bony structures and teeth
Fetal exposure
Tooth enamel dysplasia
Irregularities in bone growth
Younger children (under age 8)
Enamel dysplasia and crown deformation when permanent teeth appears
(impaired long bone formation ) (discolouration of teeth)
- Hepatic toxicity of tetracycline
hepatic necrosis
High doses in pregnant women and those with preexisting renal disease may impair liver function
renal toxicity in tetracycline
Fanconi’s syndrome
Renal tubular acidosis
Intake of outdated tetracycline
Fanconi’s syndrome
Enhanced skin sensitivity to ultraviolet light caused by which tetracycline
Demeclocycline
which 2 AB causes Dose-dependent reversible dizziness and vertigo
Doxycycline and minocycline
inhibition of transpeptidation by chloramphenicol is catalyzed by
peptidyl transferase
mode of excretion of chloramphenicol
urine
Rarely used as a systemic drug
chloramphenicol
drug that becomes bactericidal for some strains
chloramphenicol
drug that is commonly used as topical agent (As its clinical use)
chloramphenicol
cytopenia caused by chloramphenicol is ___-dependent
dose dependent
cytopenia caused by chloramphenicol is reversible or irreversible
reversible
multivalent cations
Ca, Fe, Al
if a patient has gonorrhea, he also has
chlamydia