What is the protocol for administering intramuscular (IM) penicillin after a failed oral antibiotic trial?

From the Guidelines

Intramuscular penicillin is an appropriate next step after a failed oral penicillin trial, with the recommended regimen being benzathine penicillin G administered as a single dose of 1,200,000 U for patients weighing 60 lb (27 kg) or more, and 600,000 U for those under 60 lb. This recommendation is based on the guidelines for managing group A streptococcal pharyngitis, which provide a strong, high-quality evidence base for the use of intramuscular penicillin in such cases 1. When administering, it is crucial to use proper technique, including injecting into the upper outer quadrant of the buttock or the ventrogluteal site, and aspirating before injection to avoid intravascular administration.

The choice of benzathine penicillin G is supported by its ability to provide higher and more sustained blood levels than oral formulations, which is particularly beneficial for patients with poor medication adherence, absorption problems, or infections caused by organisms with reduced susceptibility to oral agents. Although other studies, such as those related to sexually transmitted diseases, recommend different dosages, such as 2.4 million units IM in a single dose 1, the most recent and relevant guideline for the context provided prioritizes the dosage based on patient weight as outlined in the 2013 guideline 1.

Key considerations for the administration of intramuscular penicillin include:

• Using the appropriate dose based on patient weight
• Administering the injection correctly to minimize discomfort and risk of adverse effects
• Monitoring patients for 30 minutes after injection due to the risk of anaphylaxis
• Recognizing the potential for pain at the injection site as a common side effect, which can be mitigated with proper technique and by allowing the medication to reach room temperature before administration.

From the FDA Drug Label

DOSAGE AND ADMINISTRATION Streptococcal Infections Group A—Infections of the upper-respiratory tract, skin and soft-tissue infections, scarlet fever, and erysipelas. The following doses are recommended: Adults and pediatric patients over 60 lbs. in weight: 2,400,000 units. Pediatric patients from 30 to 60 lbs.: 900,000 units to 1,200,000 units. Pediatric patients under 30 lbs. : 600,000 units. Method of Administration Bicillin C-R is intended for Intramuscular Injection ONLY. Do not inject into or near an artery or nerve, or intravenously or admix with other intravenous solutions. Administer by DEEP INTRAMUSCULAR INJECTION in the upper, outer quadrant of the buttock In neonates, infants and small children, the midlateral aspect of the thigh may be preferable. When doses are repeated, vary the injection site.

The protocol for administering intramuscular (IM) penicillin after a failed oral antibiotic trial is:

• Dose:
  • Adults and pediatric patients over 60 lbs: 2,400,000 units
  • Pediatric patients from 30 to 60 lbs: 900,000 units to 1,200,000 units
  • Pediatric patients under 30 lbs: 600,000 units
• Administration:
  • Administer by DEEP INTRAMUSCULAR INJECTION
  • Inject in the upper, outer quadrant of the buttock (or the midlateral aspect of the thigh in neonates, infants, and small children)
  • Vary the injection site when doses are repeated 2

From the Research

Protocol for Administering Intramuscular (IM) Penicillin

• The protocol for administering IM penicillin after a failed oral antibiotic trial is not explicitly stated in the provided studies, but the studies suggest that IM penicillin G benzathine is an effective treatment for streptococcal pharyngitis 3, 4, 5.
• The dosage of IM penicillin G benzathine varies, but a common dosage is 600,000 U for children who weigh less than 60 pounds, and 1.2 million U for children who weigh more than 60 pounds 4.
• The studies also suggest that combining IM penicillin G benzathine with procaine penicillin G can reduce the incidence of local reactions and improve patient compliance 4.
• In terms of reducing injection pain, the studies suggest that administering local anesthetics such as lidocaine or mepivacaine with IM penicillin G benzathine can be effective in reducing post-injection pain scores 6.
• The American Heart Association recommends that patients with a history of rheumatic fever receive IM penicillin G benzathine every 3-4 weeks for 10 years, or until age 40, or lifelong 3, 6.

Considerations for Administration

• The studies highlight the importance of considering the patient's weight and medical history when administering IM penicillin G benzathine 4, 5.
• The use of local anesthetics to reduce injection pain is also an important consideration, particularly for patients who require long-term treatment with IM penicillin G benzathine 6.
• The studies also emphasize the need for proper technique and sterile procedures when administering IM injections to minimize the risk of adverse reactions 6.