Antibiotics

Question 1

What are concentration dependent and time dependent killing?

Answer 1

To do with:
MIC: minimum inhibitory concentration required to completely inhibit growth in vitro
MBC: as above but kill.

Three important factors: peak serum level (Cmax), Cmin and AUC.

Concentration dependent killing = maximise time in effective concentration
Time dependent = maximise duration of exposure

Question 2

Give a basic overview of penicillin?

Answer 2

Thiazolidine ring attached to a B lactam ring. Attached to a different amino acid side chain for each different agent. Beta lactam ring binds to bacterial cell wall proteins and inhibits formation of peptidoglycan cross links. These maintain cell wall stability and disruption causes cytolysis and death

Question 3

How does penicillin resistance develop?

Answer 3

Drug inactivation! Beta lactamase
Alteration of pen binding proteins
Alteration of bacterial cell wall permeability

Question 4

Penicillin side effects?

Answer 4

Hypersensitivity: beta lactam ring. 10% have cross sensitivity to other beta lactams. Cephalosporins, monobactams and carbopenems
Encephalopathy in renal failure
Rash