AMPICILLIN

Antibacterial Activity

Effective against most gram-positive including enteroccoci
Effective against some gram-negative (eg. H. influenza, E. coli, salmonella, shigella, P. mirabilis)
Effective against some anaerobes
Not effective against  b-lactamase producing organisms

Pregnancy Risk Factor

Category B

Contraindication/Precaution

Hypersensitivity to ampicillin or any penicillins or any component
Do not use if Pseudomembranous colitis
Use caution with patient who are allergic to cephalosporin, they could have an hypersensibility to penicillins
Use caution if EBV, CMV or LLA: may develop rash
Use caution if impaired renal function

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: 
1 hour, change with renal function.
Elimination: 
excreted  in urine

Dosage

Children: (max 12 g/day) (doses are higher for meningitis Tx: see Meningitis, Bacterial)

Body weight < 2000 g 0-7 days old: 50 mg/kg/day IM/IV div q12h 8-28 days old: 75 mg/kg/day  IM/IV div q8h Body weight > 2000 g
0-7 days old: 75 mg/kg/day  IM/IV div q8h
8-28 days old: 100 mg/kg/day  IM/IV div q6h
> 28 days old: 50-300 mg/kg/day IM/IV div q6h

Adults: 

250-2000 mg IM/IV/PO q6h

Dosage In Renal Failure

Creatinine clearance (ml/min):
<10: same dose but q12-24h 10-50: same dose but q6-12h 50-80: unchanged >80: unchanged
Dialysis
Hemo: post dialysis dose=250 mg IM/IV/PO
CAPD: 250 mg IM/IV/PO q12h