Therapeutic Classification: anti-infectives
Pharmacologic Classification: aminopenicillins
Absorption: Moderately absorbed from the duodenum (30–50%).
Distribution: Diffuses readily into body tissues and fluids. CSF penetration is ↑ in the presence of inflamed meninges.
Metabolism/Excretion: Variably metabolized by the liver (12–50%). Renal excretion is variable (25–60% after oral dosing; 50–85% after IM administration).
Half-Life: Neonates: 1.7–4 hr; Children and Adults: 1–1.5 hr (↑ in renal impairment).
Respiratory and Soft-Tissue Infections
- PO (Adults and Children ≥20 kg): 250–500 mg every 6 hr.
- PO (Children <20 kg): 50–100 mg/kg/day in 3–4 divided doses (not to exceed 2–3 g/day).
- IM IV (Adults and Children ≥40 kg ): 500 mg–3 g every 6 hr (not to exceed 14 g/day).
- IM IV (Children <40 kg): 100–200 mg/kg/day in 3–4 divided doses (not to exceed 12 g/day).
Bacterial Meningitis Caused by H. influenzae, Streptococcus pneumoniae, Group B streptococcus, or N. meningitidis; Septicemia
- IM IV (Adults ): 500 mg–3 g every 6 hr (not to exceed 14 g/day).
- IM IV (Children >1 mo): 200–400 mg/kg/day in 4 divided doses (not to exceed 12 g/day).
- IM IV (Neonates ≤7 days): 200 mg/kg/day in 3 divided doses.
- IM IV (Neonates >7 days): 300 mg/kg/day in 4 divided doses.
GI/GU Infections other than N. gonorrhoeae
- PO (Adults and Children >20 kg): 250–500 mg every 6 hr (larger doses for more serious/chronic infections).
- PO (Children ≤20 kg): 50–100 mg/kg/day in 4 divided doses.
N. gonorrhoeae
- PO (Adults ): 3 g as single dose with 1 g probenecid.
- IM IV (Adults and Children ≥40 kg ): 500 mg every 6 hr.
- IM IV (Children <40 kg): 100–200 mg/kg/day in 3–4 divided doses.
Urethritis Caused by N. gonorrhoeae in Men
- IM IV (Adults and Children ≥40 kg ): 500 mg, repeated 8–12 hr later; additional doses may be necessary for more complicated infections (prostatitis, epididymitis).
Prevention of Bacterial Endocarditis
- IM IV (Adults ): 2 g 30 min before procedure (gentamicin may be added for high-risk patients); additional 1 g may be given 6 hr later for high-risk patients.
- IM IV (Children ): 50 mg/kg (not to exceed 2 g) 30 min before procedure (gentamicin may be added for high-risk patients); additional 25 mg/kg may be given 6 hr later for high-risk patients.
Renal Impairment
- (Adults and Children ): CCr ≤10 mL/min: ↑dosing interval to every 12 hr.
