Cell Wall Synthesis Inhibitors Flashcards
What is the classification of Penicillin G?
penicillin
bactericidal
beta-lactam antibiotic
What is the mechanism of action of Penicillin G?
Cell wall synthesis inhibition - Inhibits transpeptidase enzyme which leads to the disruption of peptidoglycan (cell wall) synthesis, these defects in the cell wall leads to rupturing.
What is the spectrum of activity of Penicillin G?
narrow
What are the therapeutic indications of Penicillin G? (6)
- G+ cocci - tonsillitis, Pneumococci
- G- cocci – meningitis, gonorrhoea
- G+ bacilli/rod - tetanus, gangrene
- Bacteroides fragilis (oropharyngeal infections)
- Treponema (syphilis)
- Actinomyces (abscesses)
Why can Penicillin G not be administered orally?
It is acid labile (inactivated by gastric acid) which causes it to have a poor absorption in the GIT
How is Penicillin G administered?
intramuscular (IM) and intravenous (IV)
What % of Penicillin G is bound to plasma proteins?
50-60%
What is the T1/2 of Penicillin G and how does this affect excretion
Short (30 mins), so rapidly eliminated unchanged via kidneys
In which 3 ways can the effect of Penicillin G be prolonged?
- Higher doses
- Combined with probenecid
- IM administration in depot form
What are 3 Disadvantages of Penicillin G?
- Narrow spectrum of action
- Acid-labile (so only parental administration)
- beta-lactamase sensitive (inactivated by bacterial enzymes)
What are the 2 major adverse effects of Penicillin G?
Hypersensitivity reaction and Neurotoxic effects (convulsions)
What is the classification of Penicillin V
beta-lactam antibiotic
penicillin
What is the mechanism of action of Penicillin V?
Cell wall synthesis inhibition
What is the spectrum of activity of Penicillin V?
narrow
What are the therapeutic indications of Penicillin V?
- less severe infections
- follow-up antibiotic after successful parenteral treatment of severe infections
How is Penicillin V administered?
orally (acid stable)
How is the % of Penicillin V oral-dose that is absorbed impaired?
impaired by food intake
What is the half-life of Penicillin V?
30min
What % of Penicillin V is bound to plasma proteins?
80%
Where is Penicillin V metabolised?
liver
By which organ is unchanged Penicillin V excreted?
kidneys
What are the adverse effects of Penicillin V?
Similar to Penicillin G
What is the classification of Cloxacillin/ Flucloxacillin?
beta-lactam antibiotic
Isoxazolyl penicillin
semisynthetic penicillin
What is the mechanism of action of Cloxacillin/ Flucloxacillin?
Cell wall synthesis inhibition
What are the therapeutic indications of Cloxacillin/ Flucloxacillin?
They are sensitive to beta-lactamase- resistant isolates of S aureus (normally resistant to Penicillin G)
How is Cloxacillin/ Flucloxacillin administered?
Orally (acid stable), otherwise IM and IV
How is the % of Cloxacillin/ Flucloxacillin oral-dose that is absorbed impaired?
impaired by food intake
What is the half-life of Cloxacillin/ Flucloxacillin?
30-60min
By which organ is Cloxacillin/ Flucloxacillin excreted?
kidneys
What are the adverse effects of Cloxacillin/ Flucloxacillin?
Similar to Penicillin G
What is the classification of Ampicillin?
beta-lactam antibiotic
aminopenicillin
What is the mechanism of action of Ampicillin?
Cell wall synthesis inhibition
What is the spectrum of activity of Ampicillin?
broad-spectrum of activity
What are the therapeutic indications of Ampicillin? (3)
- gram-positive bacteria
- gram-negative cocci
- gram-negative bacilli : H. influenzae, Salmonella, Shigella, Proteus mirabilis and Entamoeba coli.
How is Ampicillin administered?
orally (acid stable), also parentally
How is the % of Ampicillin that is absorbed impaired?
impaired with food intake
What % Ampicillin is bound to plasma proteins?
17-20%
What is the half-life of Ampicillin?
80min