Penicillin G
PFIZERPEN, BICILLIN L-A
What it isNatural beta-lactam inhibiting PBPs, given parenterally; syphilis and susceptible streptococcal or enterococcal infection.
Why this oneBenzathine penicillin G is the only accepted treatment for syphilis in pregnancy.
What limits itA very short half-life for the aqueous form requires frequent dosing. Jarisch-Herxheimer reaction in syphilis; beta-lactamase producers escape it.
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Serious streptococcal infections (septicemia, pneumonia, endocarditis, meningitis) | adult | 12-24 million units/day divided q4-6h | ||
| Serious staphylococcal infections | adult | 5-24 million units/day divided q4-6h | ||
| Meningococcal meningitis/septicemia | adult | 24 million units/day as 2 million units q2h | ||
| Neurosyphilis | adult | 12-24 million units/day (2-4 MU q4h) x10-14 days | ||
| Anthrax | adult | min 8 million units/day divided q6h | ||
| Serious infections (strep/meningococcus) | pediatric | 150,000-300,000 units/kg/day divided q4-6h | ||
| Meningitis (pneumococcus/meningococcus) | pediatric | 250,000 units/kg/day divided q4h x7-14 days | 12-20 million units/day |
Renal CrCl <10 mL/min/1.73m2: full loading dose then 1/2 loading dose q8-10h. CrCl >10 (uremic): full loading dose then 1/2 loading dose q4-5h.
Hepatic Additional dose modification needed when hepatic disease coexists with renal impairment.
Do not give <1 million units per dose to pediatric patients.
Instructions
- Administer by IV infusion
- Give in divided doses (short half-life), usually q4-6h (q2h for meningococcal meningitis)
- Inspect for particulate matter and discoloration before use
Contraindications
- History of anaphylactic (hypersensitivity) reaction to any penicillin
- Dextrose-containing solutions in patients with known corn allergy
Cautions
- Serious/fatal hypersensitivity and anaphylaxis
- Jarisch-Herxheimer reaction in spirochetal infections
- Electrolyte disturbances (hyperkalemia; 1 MU contains 1.7 mEq K+) with large IV doses
- Neurotoxicity - seizures, myoclonus - with massive doses or renal impairment
- C. difficile / pseudomembranous colitis
- Interstitial nephritis; Coombs-positive hemolytic anemia at high doses
Adverse reactions
- Hypersensitivity reactions (urticaria, angioedema, anaphylaxis, serum sickness)
- Jarisch-Herxheimer reaction
- Neutropenia; Coombs-positive hemolytic anemia
- Hyperkalemia and electrolyte disturbance
- Seizures/neurotoxicity with massive IV doses
- Phlebitis, thrombophlebitis, injection-site pain
- Interstitial nephritis
Pregnancy Animal studies show no fetal harm; no adequate controlled human studies - use only if clearly needed.
Lactation Undefined
⚠ BOXED WARNING
- Not for intravenous use; inadvertent IV injection has caused arrest
Cost, est. cash$20–$1,500/dose or month
Generic entry1988
Classes and tags
Clinical profile
Legacy pregnancy categoryB
Defining liabilityAllergy, gastrointestinal effects and agent-specific renal, hepatic, hematologic or interaction risks.
Mechanism of action: Penicillin G ballicule
Open Penicillin G in the interactive console ↗
Memory aids: mascots and interaction avatars
