Benzylpenicillin
General Information
A penicillin antibiotic. Do NOT use if patient is allergic to penicillin.
Formulary antimicrobial: Use in accordance with Trust guidelines
AWaRe antibiotic classification: 'Access'. Use as per guidelines.
Dosing
| Intravenous benzylpenicillin | |
| Standard dose | 1.2g QDS |
| Severe infection |
Dose can be increased up to 14.4g per day in 4-6 divided doses (e.g. 2.4g every 4 hours or 3.6g every 6 hours) |
Obesity
Dosing for penicillins should be at the upper end of recommended ranges, particularly for morbidly obese patient with severe infections, considering patient’s renal function.
Renal and hepatic impairment
Renal impairment
|
eGFR (mL/min/1.73m2) |
Intravenous benzylpenicillin |
|
More than 20 |
No adjustment |
|
10-20 |
600mg - 2.4g QDS depending on severity of infection |
|
Less than 10 |
600mg –1.2g QDS depending on severity of infection. Maximum dose in severe renal impairment 4.8g per day |
|
HD/HDF/High Flux/PD |
600mg –1.2g QDS depending on severity of infection. Maximum dose 4.8g per day HD/HDF/High Flux/PD: Dialysed; give after dialysis |
Hepatic impairment
Reduce dose to 300mg TDS, if advanced liver disease is associated with severe renal failure.
Notable Interactions
Methotrexate: Benzylpenicillin can reduce excretion of methotrexate (increased risk of toxicity).
Vitamin K antagonists: Appropriate monitoring should be undertaken. It would be prudent to monitor coagulation status within 3 days of starting or stopping a penicillin.
This is not a complete list. Please see the BNF, Summary of Product Characteristics or speak to a pharmacist.
Pregnancy and breastfeeding
Pregnancy
Safe
Breastfeeding
Safe, trace amounts in milk. Monitor infant for gastro-intestinal disturbances and oral candida infection, especially if used for prolonged periods or in high doses, although these effects are unlikely to occur. There is also a theoretical risk of hypersensitivity.
Additional information
600mg of benzylpenicillin contains 38.6mg of sodium. This is equivalent to 1.9% of the WHO recommended maximum daily intake of sodium for an adult.
References
- Benzylpenicillin Sodium 600 mg powder for solution for injection / infusion [online]. Manufacturer - Sandoz Limited – last updated: 2022 Aug 24. Accessed via: www.emc.medicines.org.uk [Accessed 2023 Aug 24].
- The Renal Drug Database. Benzylpenicillin - last updated: 2019 Sep 9. Accessed via: https://renaldrugdatabase.com [Accessed 2023 Aug 21].
- UK Medicines Information. How should antibiotics be doses in obesity – last updated 2017 Mar 1. Accessed via: https://www.gloshospitals.nhs.uk/media/documents/Obese_Dosing_2016_update.pdf [Accessed 2022 Nov 23].
- Specialist Pharmacy Service – Lactation Safety Information: Benzylpenicllin – last updated 2020 Aug 5. Accessed via: https://www.sps.nhs.uk/medicines [Accessed 2023 Aug 21].
- Briggs GG, Freeman RK, Towers CV, Forinash AB. Briggs Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk [online]. Lippincott Williams & Wilkins; 2021 Feb 18. Accessed via https://online.lexi.com [Accessed 2022 Nov 23].
- UK Teratology Information Service - USE OF PENICILLINS IN PREGNANCY – last updated 2019 Jan. Accessed via: https://www.uktis.org/ [Accessed 2023 Aug 21]