Penicillin G Potassium

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Cat Number

API0232172

CAS Number

113-98-4

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Product Detail Description Scientific Support Customer Q&A

CAS Number

113-98-4

EINECS

204-038-0

Synonyms

Pfizerpen, Benzylpenicillin potassium, Potassium benzylpenicillin, Penicillin G potassium salt

Molecular Formula

C16H17KN2O4S

Molecular Weight

372.48

Smiles

CC1([C@@H](N2[C@H](S1)[C@@H](C2=O)NC(=O)CC3=CC=CC=C3)C(=O)[O-])C.[K+]

Appearance

Colorless or white crystal, or white crystalline powder

Melting Point

214-217℃

General Description

Penicillin G potassium is the potassium salt of natural penicillin G (benzylpenicillin), formulated as a white crystalline powder for parenteral administration. It is supplied as a sterile powder for reconstitution and is intended for intramuscular or intravenous use due to its poor oral absorption and acid lability. Each million units contains approximately 1.7 mEq of potassium, requiring consideration in patients with electrolyte imbalances or renal impairment.

Mechanism of Action

Penicillin G exerts bactericidal activity by binding to penicillin-binding proteins and inhibiting the final transpeptidation step of bacterial cell wall synthesis, thereby blocking cross-linking of peptidoglycan. This results in osmotic instability and cell lysis, with activity limited to actively multiplying organisms. The drug is susceptible to inactivation by bacterial beta-lactamases and demonstrates poor penetration through the outer membrane of gram-negative rods.

Application

Penicillin G potassium is indicated for serious infections caused by susceptible organisms including streptococci, pneumococci, meningococci, and Treponema pallidum. Specific indications include streptococcal endocarditis, pneumococcal pneumonia, meningococcal meningitis, anthrax, diphtheria, tetanus, gas gangrene, and neurosyphilis. Dosing ranges from 2 to 30 million units daily divided every 4 to 6 hours depending on infection severity, with dosage adjustment required in renal impairment.

Padari H, et al. characterized penicillin G disposition in neonates with gestational age ≥32 weeks and postnatal age <72 hours, combining noncompartmental analysis (n=16) with population modeling that included extremely preterm neonates. Probability of target attainment simulations, accounting for 40% protein binding, demonstrated that a 25,000 IU/kg dose administered every 12 hours achieves >90% target attainment (unbound concentration above MIC for 40% of the dosing interval) for MIC values ≤2 mg/L.

Fig. 1 Goodness-of-fit plots from the final population pharmacokinetic model. (Padari H, et al., 2018)

References

Padari H, et al. Pharmacokinetics of Penicillin G in Preterm and Term Neonates. Antimicrob Agents Chemother. 2018;62(5):e02238-17.

Is Penicillin G Potassium extremely moisture-sensitive during storage?

Yes, it is highly hygroscopic and susceptible to hydrolysis, which destroys the beta-lactam ring. It must be stored in airtight, moisture-proof containers with desiccant.

What is the recommended storage temperature for maintaining Penicillin G Potassium potency?

Storage at 2-8°C is recommended for long-term stability. At room temperature, degradation accelerates significantly, leading to loss of potency and increased impurities.

Does Penicillin G Potassium require special handling due to its allergenic potential?

Absolutely. It is a known sensitizer. Personnel handling the API should wear appropriate PPE, and spills must be cleaned immediately to prevent airborne dust exposure.

How is the potency of Penicillin G Potassium verified microbiologically?

We use both HPLC for chemical purity and a validated microbiological assay to confirm its biological activity against a standard test organism, ensuring therapeutic efficacy.