PENICILLIN G POTASSIUM IN PLASTIC CONTAINER
Clinical safety rating: safe
Probenecid may decrease excretion Serious and occasionally fatal hypersensitivity reactions have been reported.
Penicillin G is a beta-lactam antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), inhibiting transpeptidation and activating autolytic enzymes.
| Metabolism | Penicillin G is primarily metabolized by hydrolysis to penicilloic acid, which is inactive. It is also metabolized via renal tubular secretion and glomerular filtration. |
| Excretion | Renal: 60–90% unchanged via tubular secretion and glomerular filtration. Biliary/fecal: <10%. |
| Half-life | 0.5–1 hour (normal renal function). Prolonged in renal impairment (up to 7–10 hours in anuria). |
| Protein binding | Approximately 60% bound to serum albumin. |
| Volume of Distribution | 0.3–0.5 L/kg; limited distribution, primarily extracellular fluid. |
| Bioavailability | IM: 60–80% due to partial degradation at injection site. Oral: Not applicable (acid-labile, not orally administered). |
| Onset of Action | IV: Immediate (minutes). IM: 15–30 minutes. |
| Duration of Action | IV: 4–6 hours (rapidly cleared). IM: 6–8 hours due to slower absorption. |
| Molecular Weight | 372.49 |
2-4 million units IV every 4 hours for moderate to severe infections; up to 24 million units/day for serious infections (meningitis, endocarditis).
| Dosage form | INJECTABLE |
| Renal impairment | CrCl >50 mL/min: no adjustment; CrCl 10-50 mL/min: administer every 6-8 hours; CrCl <10 mL/min: administer every 8-12 hours. |
| Liver impairment | No dose adjustment required for hepatic impairment. |
| Pediatric use | Neonates: <7 days, 50,000 units/kg/dose IV every 12 hours; 7-28 days, 75,000 units/kg/dose IV every 8 hours. Infants and children: 100,000-250,000 units/kg/day IV divided every 4-6 hours; maximum 24 million units/day. For meningitis: 250,000-400,000 units/kg/day IV divided every 4-6 hours. |
| Geriatric use | Adjust dose based on renal function; consider lower initial doses due to age-related decline in GFR; monitor for electrolyte disturbances (hyperkalemia) and neurotoxicity. |
| 1st trimester | Penicillin G is generally considered safe during the first trimester. Studies have not shown an increased risk of major birth defects. |
| 2nd trimester | Safe for use during the second trimester. No evidence of fetal harm. |
| 3rd trimester | Safe for use during the third trimester. However, caution is advised due to potential alteration of gut flora in the newborn. |
Clinical note
Probenecid may decrease excretion Serious and occasionally fatal hypersensitivity reactions have been reported.
| FDA category | Human |
| Placental transfer | Penicillin G crosses the placenta readily, achieving therapeutic concentrations in fetal tissues and amniotic fluid. |
| Breastfeeding |
■ FDA Black Box Warning
WARNING: SERIOUS HYPERSENSITIVITY REACTIONS, INCLUDING ANAPHYLAXIS, HAVE BEEN REPORTED IN PATIENTS ON PENICILLIN THERAPY. BEFORE INITIATING THERAPY, CAREFUL INQUIRY SHOULD BE MADE CONCERNING PREVIOUS HYPERSENSITIVITY REACTIONS TO PENICILLINS, CEPHALOSPORINS, OR OTHER ALLERGENS. IF AN ALLERGIC REACTION OCCURS, DISCONTINUE PENICILLIN G AND INSTITUTE APPROPRIATE THERAPY.
| Common Effects | Diarrhea |
| Serious Effects |
Hypersensitivity to penicillinsHistory of severe allergic reaction to beta-lactam antibiotics
| Precautions | Hypersensitivity reactions including anaphylaxis, Clostridium difficile-associated diarrhea, Electrolyte disturbances (hyperkalemia with potassium salt), Neurologic adverse effects (seizures) with high doses or renal impairment, Thrombophlebitis at injection site, Use with caution in patients with renal impairment or history of allergies |
| Food/Dietary |
Loading safety data…
| Penicillin G is excreted into breast milk in low concentrations. It is generally considered compatible with breastfeeding, but may cause diarrhea or allergic reaction in the infant. |
| Lactation Rating | L1 (Safe) |
| Teratogenic Risk | Penicillin G potassium is generally considered safe during pregnancy. No teratogenic effects have been reported in human studies across all trimesters. However, as with all medications, use only if clearly needed. |
| Fetal Monitoring | Monitor maternal vital signs and for signs of hypersensitivity reactions. Fetal monitoring not routinely required unless maternal condition warrants. |
| Fertility Effects | No known adverse effects on fertility in animal or human studies. |
| No significant food-drug interactions. However, avoid alcohol consumption during treatment as it may exacerbate side effects or reduce efficacy. No dietary restrictions required. |
| Clinical Pearls | Penicillin G potassium in plastic container is a first-line agent for syphilis, group A streptococcal infections, and prophylaxis for rheumatic fever. It is inactivated by gastric acid, so it must be administered parenterally (IV or IM). Monitor potassium levels in patients with renal impairment due to potassium content (~1.7 mEq per million units). Use caution in patients with history of severe allergy to penicillins; cross-reactivity with cephalosporins is low but possible. For neurosyphilis, high-dose IV therapy is required. Record via IV infusion over 1-2 hours to avoid vein irritation. In neonates, use only after cultures confirm need. |
| Patient Advice | This medication is given as an injection or infusion into a vein or muscle, not by mouth. · Complete the entire course of therapy even if you feel better to prevent resistance. · Notify your doctor immediately if you experience rash, hives, difficulty breathing, or swelling of the face or throat. · This formulation contains potassium; if you have kidney problems, your doctor will monitor your potassium levels. · Do not stop treatment early without consulting your healthcare provider. |