BUGS & DRUGS

• Amoxicillin-clavulanate

  • Formulations are not interchangeable. You must prescribe the correct formulation and dosing combination of amoxicillin-clavulanate to assure efficacy and to prevent side effects such as severe diarrhea.

    • Amoxicillin-Clavulanate Formulation-Based Dosing (amoxicillin:clavulanate) (NOTE: max dosing based on amoxicillin component)

      • 14:1 Formulation: 90 mg/kg/day divided in 2 doses, max 4000 mg per day

        • Available 14:1 formulation:

          • amoxicillin 600 mg/clavulanate 42.9 mg

      • 7:1 Formulation: 25–45 mg/kg/day divided in 2 doses, max 1750 mg per day

        • Available 7:1 formulations:

          • amoxicillin 200 mg/clavulanate 28.5 mg

          • amoxicillin 400 mg/clavulanate 57 mg

          • amoxicillin 875 mg/clavulanate 125 mg​

      • 4:1 Formulation: 20–40 mg/kg/day divided in 3 doses, max 1500 mg per day

        • Available 4:1 formulations:

          • amoxicillin 125 mg/clavulanate 31.25 mg

          • amoxicillin 250 mg/clavulanate 62.5 mg

          • amoxicillin 500 mg/clavulanate 125 mg

      • 16:1 Formulation: Extended-Release, ONLY for those >40 kg:  2000 mg every 12 hours

        • Available 16:1 formulations:

          • amoxicillin 1000 mg/clavulanate 62.5 mg

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• Vancomycin

  • Troughs should be obtained immediately (0 to 30 minutes) prior to the 4th dose (i.e., after the 3rd dose, at steady state)

    • Troughs should be repeated weekly or with any change in dose (prior to the 4th dose on a new dosing regimen) or change in renal function

  • Goal trough is 10-15 mcg/mL for most indications unless otherwise specified by infectious diseases

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• *For patients with a CrCl <75mL/min/1.73m²or acute renal impairment, administer one time dose of vancomycin and check level following this dose

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• Approach to a Patient with a History of Penicillin Allergy​​

• Incidence of penicillin reactions

  • Risk of acute penicillin allergy occurs in ~1% of the general population

    • Incidence of anaphylactic reactions: ≤0.015%

  • ~90% of patients who report an allergy to penicillin have negative skin test results and are NOT at an increased risk of an acute allergic reaction

    • A careful history is required to assess true allergy

• Rate of cross-reactivity between penicillins (e.g., penicillin, amoxicillin, oxacillin, piperacillin/tazobactam) and cephalosporins varies based on similarity of side chains

  • Risk of cross-reactivity is greater with 1st generation cephalosporins than 3rd or 4th generation cephalosporins

    • 1st and 2nd generation: <5%

    • 3rd generation: <2%

    • Carbapenems: <1%

• Any patient who has a history consistent with anaphylaxis (immediate or accelerated) should NOT receive ANY beta-lactams (penicillins, cephalosporins, or carbapenems) without undergoing skin testing first

• Beta-lactams should be avoided in patients with documented severe delayed adverse reactions such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug rash with eosinophilia and systemic symptoms syndrome (DRESS)

 

• Questions to Ask Family

1. How long after beginning penicillin did the reaction occur?

2. Was there any wheezing, throat/mouth swelling, hives, or generalized itching?

3. If a rash occurred, what was the nature of the rash? Where was it and what did it look like?

4. Was the patient on other medications at the time of the reaction?

5. Since then, has the patient ever received another penicillin or cephalosporin (ask about brand names such as Augmentin, Keflex, Ceftin, Trimox, Vantin)?

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