DURACILLIN A.S.
Clinical safety rating: caution
Comprehensive clinical and safety monograph for DURACILLIN A.S. (DURACILLIN A.S.).
Penicillin G procaine is a beta-lactam antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), leading to cell lysis and death.
| Metabolism | Primarily renal excretion as unchanged drug; minor hepatic metabolism. |
| Excretion | Primarily renal (60-90% unchanged via tubular secretion and glomerular filtration); minor biliary/fecal elimination (<10%) |
| Half-life | 0.5-1 hour in adults with normal renal function; prolonged to 7-10 hours in end-stage renal disease |
| Protein binding | 60-80% bound primarily to albumin |
| Volume of Distribution | 0.3-0.4 L/kg; limited distribution into CSF, eyes, and prostate unless inflamed |
| Bioavailability | Intramuscular: 100% (complete absorption from depot); Oral: not applicable (not orally administered) |
| Onset of Action | Intramuscular: 1-2 hours for detectable serum levels; clinical effect within 12-24 hours due to slow release from depot |
| Duration of Action | Intramuscular: 12-24 hours for procaine penicillin; single dose provides therapeutic concentrations for 24 hours, requiring daily dosing for most infections |
| Molecular Weight | 356.47 |
600,000 units intramuscularly once daily; or 1.2 million units intramuscularly every 12 hours for severe infections.
| Dosage form | INJECTABLE |
| Renal impairment | No adjustment required; drug is minimally renally excreted. |
| Liver impairment | No adjustment required; drug is not hepatically metabolized. |
| Pediatric use | Neonates: 50,000 units/kg intramuscularly once daily; Infants and children: 50,000 units/kg intramuscularly once daily (maximum 2.4 million units/day). |
| Geriatric use | No specific adjustment; use with caution due to increased risk of adverse effects. |
| 1st trimester | Penicillin G procaine crosses the placenta. No well-controlled studies in humans; however, penicillin antibiotics are generally considered safe during pregnancy. Risk cannot be excluded. |
| 2nd trimester | Penicillin G procaine crosses the placenta. No well-controlled studies in humans; however, penicillin antibiotics are generally considered safe during pregnancy. Risk cannot be excluded. |
| 3rd trimester | Penicillin G procaine crosses the placenta. No well-controlled studies in humans; however, penicillin antibiotics are generally considered safe during pregnancy. Risk cannot be excluded. |
Clinical note
Comprehensive clinical and safety monograph for DURACILLIN A.S. (DURACILLIN A.S.).
| Placental transfer | Penicillin G crosses the placenta. Transfer is low to moderate, with fetal concentrations typically less than maternal serum levels. |
| Breastfeeding | Penicillin G is excreted into breast milk in small quantities. The American Academy of Pediatrics considers penicillin G compatible with breastfeeding. However, potential for modification of bowel flora or allergic sensitization in the infant exists. Use with caution. |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
Hypersensitivity to penicillinHypersensitivity to procaine
| Precautions | Severe hypersensitivity reactions (anaphylaxis) can occur, Use caution in renal impairment (requires dose adjustment), Risk of neurotoxicity with high doses or prolonged use, Procaine reactions (anxiety, confusion, hallucinations) may occur, Monitor for superinfection |
| Food/Dietary | No significant food interactions. Alcohol should be avoided as it may increase the risk of adverse reactions such as nausea, vomiting, and headache. |
| Clinical Pearls |
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| Lactation Rating | L2 |
| Teratogenic Risk | Penicillin G procaine (Duracillin A.S.) is classified as FDA Pregnancy Category B. Animal studies have not demonstrated fetal risk, and there are no adequate well-controlled studies in pregnant women. However, penicillin antibiotics are generally considered safe in pregnancy. No specific teratogenic effects have been reported in first, second, or third trimester. Use only if clearly needed. |
| Fetal Monitoring | Monitor for allergic reactions, including anaphylaxis. In prolonged therapy, monitor renal and hematologic function. Fetal monitoring is not specifically required but standard obstetric care applies. |
| Fertility Effects | No known adverse effects on fertility. Animal studies have not shown impaired fertility. Clinical data insufficient to conclude any impact on human fertility. |
| Always rotate injection sites to reduce the risk of sterile abscess formation. Use a separate syringe and needle for each injection. Never administer IV; for IM use only. Observe patient for 30 minutes post-injection for immediate hypersensitivity reactions. In adults, inject deep into the upper outer quadrant of the gluteus maximus; in children under 2, use the mid-lateral thigh. Before each injection, ascertain penicillin allergy history and perform skin testing if indicated. For syphilis treatment, administer benzathine penicillin G 2.4 million units IM once; ensure patient receives all doses scheduled. Procaine penicillin is no longer recommended for syphilis due to resistance concerns. Benzathine penicillin is the preferred form for syphilis. |
| Patient Advice | Inform your healthcare provider immediately if you experience any signs of an allergic reaction, such as rash, hives, itching, difficulty breathing, or swelling of the face, lips, tongue, or throat. · This medication must be given as a deep intramuscular injection by a healthcare professional; it should never be injected into a vein or given orally. · Complete the full course of injections even if you feel better to ensure the infection is completely treated. · Rotate injection sites if multiple doses are needed to prevent tissue damage. · Tell your provider about all other medications you are taking, including over-the-counter drugs and supplements. · Avoid alcohol consumption while on treatment to reduce the risk of adverse effects. · Contact your doctor if you develop severe muscle pain, redness, or swelling at the injection site. · If you are pregnant or breastfeeding, discuss the risks and benefits with your healthcare provider. · Store medication in the refrigerator, do not freeze, and protect from light. |