Amoxicillin (amoxycillin)

Amoxicillin (aka amoxycillin)

[one tablet 6 cents; 1 vial for IV injection $2.17]

ADMINISTRATION ROUTES:

  • IV, PO, NG

ALTERNATIVE NAMES:

  • Apo-Amoxi , Ospamox, Ranbaxy-Amoxi, Ibiamox

ICU INDICATIONS:

  1. treatment of infections caused by susceptible organisms
  2. empirical treatment to cover enterococcus

PRESENTATION AND ADMINISTRATION:

  • IV:
    1g vial (powder). Dilute to total of 5ml if part dose is required (making concentration of 200mg/ml). Inject slowly over 3-4 minutes or in 100ml of compatible fluid over 30-60 minutes.
    Compatible for 6 hours with normal saline, 3 hours with Hartmanns, 1 hour with D5W and glucose and sodium. (note that amoxicillin is less stable in solutions that contain glucose so it is preferable to avoid these solutions).
    Store at room temperature
  • PO / NG:
    Apo-Amoxi 250mg tablets & 500mg tablets (red/gold, marked APO and strength), Ospamox capsules 500mg capules (yellow), Ospamox suspension (125mg/5ml and 250mg/ml), Ranbaxy-Amoxi (125mg/5ml and 250mg/5ml), Amoxil paediatric drops (125mg/1.25ml), Ospamox paediatric drops (100mg/ml). administration.
  • DOSAGE:
    IV:

    1-2gm IV Q6hrly
    PO:

    500mg-1gm Q8hrly
    Liquid is preferred for NG

DOSAGE IN RENAL FAILURE AND RENAL REPLACEMENT THERAPY:

  • Dose in renal impairment [GFR (ml/min)]
    <10: 500mg every 8 hours
    10-20: dose as in normal renal function
    >20-50: dose as in normal renal function
  • Dose in renal replacement therapy
    CAPD: 500mg every 8 hours
    HD: 500mg every 8 hours
    CVVHDF: dose as in normal renal function

DOSAGE IN PAEDIATRICS:

  • IV:
    Severe infections:
    1st week of life 50mg/kg 12hrly; otherwise 50mg/kg 6hrly

CLINICAL PHARMACOLOGY:

  • Amoxicillin is bactericidal against susceptible organisms during the stage of active multiplication. It acts through the inhibition of biosynthesis of cell wall mucopeptide.
  • Amoxicillin has been shown to be active against most strains of the following microorganisms:
    Aerobic Gram-Positive Microorganisms:
    Enterococcus faecalis. Staphylococcus spp*. (beta-lactamase-negative strains only). Streptococcus pneumoniae.
    *Staphylococci which are susceptible to amoxicillin but resistant to methicillin/oxacillin should be considered as resistant to amoxicillin.
    Aerobic Gram-Negative Microorganisms:
    Escherichia coli (beta-lactamase-negative strains only). Haemophilus influenzae (beta-lactamase-negative strains only). Neisseria gonorrhoeae (beta-lactamase-negative strains only). Proteus mirabilis (beta-lactamase-negative strains only).
  • Amoxicillin diffuses readily into most body tissues and fluids, with the exception of brain and spinal fluid, except when meninges are inflamed.

CONTRAINDICATIONS:

  1. A history of allergic reaction to any of the penicillins is a contraindication.

WARNINGS

  • Anaphylaxis:
    Penicillins are a common cause of anaphylactic reactions
  • Pseudomembranous colitis:
    Pseudomembranous colitis has been reported with nearly all antibacterial agents, including amoxicillin, and may range in severity from mild to life-threatening. Therefore, it is important to consider this diagnosis in patients who present with diarrhoea subsequent to the administration of antibacterial agents.

PRECAUTIONS

  • General:
    Prescribing Amoxicillin in the absence of a proven or strongly suspected bacterial infection or a prophylactic indication is unlikely to provide benefit to the patient and increases the risk of the development of drug resistant bacteria.
  • Laboratory Tests:
    No tests in addition to routine ICU tests are required.
  • Drug/Laboratory Test Interactions:
    None noted.

IMPORTANT DRUG INTERACTIONS FOR THE ICU

  • None of significance

ADVERSE REACTIONS

  • Body as a Whole:
    Serum sickness like reactions, Anaphylaxis
  • Digestive System:
    Nausea, vomiting, diarrhea, and hemorrhagic/pseudomembranous colitis. Hepatic dysfunction including cholestatic jaundice, hepatic cholestasis and acute cytolytic hepatitis have been reported.
  • Nervous System:
    Reversible hyperactivity, agitation, anxiety, insomnia, confusion, convulsions, behavioral changes, and/or dizziness have been reported rarely.
  • Skin:
    Stevens-Johnson Syndrome, exfoliative dermatitus, toxic epidermal necrolysis, acute generalized exanthematous pustulosis, hypersensitivity vasculitis and urticaria have been reported
  • Haematological System:
    Anaemia, including hemolytic anaemia, thrombocytopaenia, thrombocytopenic purpura, eosinophilia, leukopaenia, and agranulocytosis have been reported during therapy with penicillins.

Critical Care Drug Manual

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