PENICILLIN G

Antibacterial Activity

Effective against gram-positive cocci
Effective against most anaerobe
Not effective against gram-negative aerobe or b-lactamase producing organisms

Pregnancy Risk Factor

Category B

Contraindication/Precaution

Hypersensitivity to penicillin G or any penicillins or any component 
Use caution with patient who are allergic to cephalosporin, they could have an hypersensibility to penicillins
Use caution if  seizure disorder
Use caution if impaired renal function or other nephrotoxic agents are used

Mechanism of Action

Selective inhibitors of bacterial cell wall synthesis, by binding to penicillins binding proteins (PBP'S)

Pharmacodynamics/Kinetics

Metabolism: 
liver (partially)
Half-life: 
0.5 hour, change with renal function.
Elimination: 
excreted  in urine

Dosage

Children:

Body weight < 2000 g 0-7 days old: 50000 u IV q12h 8-28 days old: 75000  u IV q8h Body weight > 2000 g
0-7 days old: 50000 u IV q8h
8-28 days old: 50000 u IV q6h
> 28 days old: 50000 u IV q6h

Adults: 

0.5-4 million u IV q4h

Dosage In Renal Failure

Creatinine clearance (ml/min):
10: give 20-50% of normal dose
10-50: give 75% of normal dose
50-80: unchanged
>80: unchanged
Dialysis
Hemo: after dialysis: give 20-50% of normal dose
CAPD: give 20-50% of normal dose