Penicillin

From IDWiki

Background

Nomenclature

  • Broadly speaking, formulations of penicillin G are soluble and used for IV or IM administration, and penicillin V is used for oral administration but does not achieve high levels in the serum
Formulation Other Names Comments
sodium penicillin G sodium benzylpenicillin

crystalline penicillin

soluble, used for IV
procaine penicillin G procaine benzylpenicillin

procaine penicilli

less soluble, used for IM
benzathine penicillin G DBED penicillin less soluble than procaine, used for IM
penicillin V phenoxymethylpenicillin used for PO, but poor absorption

Mechanism of Action

Spectrum of Activity

Clinical Breakpoints

Species Breakpoints (μg/mL) Breakpoints (mm)
S I R S I R
Anaerobes except Bacteroides ≤0.5 1 ≥2
Enterococcus ≤8 ≥16 ≥15 ≤14
Neisseria gonorrhoeae ≤0.06 0.12-1 ≥2 ≥47 27-46 ≤26
Neisseria meningitidis ≤0.06 0.12-0.25 ≥0.5
Staphylococcus ≤0.12 ≥0.25 ≥29 ≤28
Streptococcus pneumoniae ≥20
Streptococcus pneumoniae IV (nonmeningitis) ≤2 4 ≥8
Streptococcus pneumoniae IV (meningitis) ≤0.06 ≥0.12
Streptococcus pneumoniae PO (pen V) ≤0.06 0.12-1 ≥2
Streptococcus (β-hemolytic) ≤0.12 ≥24
Streptococcus (viridans group) ≤0.12 0.25-2 ≥4

Dosing

  • Benzylpenicillin (penicillin G)
    • Standard dosing: 3 million units (1.8 g) IV q4h, or 4 million units (2.4 g) IV q6h
    • High dose (for critical illness, IE, and CNS penetration): 4 million units (2.4 g ) IV q4h

Renal Dosing

Benzylpenicillin (Penicillin G)

GFR (mL/min) Standard Dose High Dose
>50 3 MU (1.8 g) IV q4h, or 4 MU (2.4 g) IV q6h 4 MU (2.4 g ) IV q4h
10-50 3 MU (1.8 g) IV q6h 3 MU (1.8 g) IV q4h
<10 3 MU (1.8 g) IV load, then 2 MU (1.2 g) IV q8h 4 MU (2.4 g) IV load, then 2 MU (1.2 g ) IV q6h
CRRT 2 MU (1.2 g) IV q6h 3 MU (1.8 g) IV q6h

Safety

Adverse Reactions

Hypersensitivity Reactions