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
- Directly inhibits penicillin-binding proteins
Spectrum of Activity
- Generally active against Gram-positive cocci, especially streptococci but some strains of Staphylococcus aureus, most clostridia, Neisseria, and some Haemophilus influenzae
- Not active against aerobic Gram-negative bacilli
- Penicillin G is generally more active than penicillin V across all bacteria
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
- Can cause any type of hypersensitivity reaction (I to IV)
- Type I: anaphylaxis and urticaria
- Type II: autoimmune hemolytic anemia
- Type III: serum sickness-like reaction
- Type IV:
- Delayed maculopapular drug rash
- Usually after 7 to 10 days of starting and up to 1 to 3 days after stopping)
- Progresses over days, with lesions that are relatively fixed
- Can worsen over a few days after stopping, then resolves over 1 to 2 weeks
- Pruritis is variable
- Most commonly occur in the context of a viral infection
- Contact dermatitis
- Delayed maculopapular drug rash