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imipenem/cilastatin (Rx)Brand and Other Names:Primaxin

 
 
 

Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

imipenem/cilastatin

powder for injection

  • 250mg/250mg
  • 500mg/500mg
more...

Lower Respiratory Tract, Skin/Skin Structure, & Gynecologic Infections

Mild to moderate: 500-750 mg IV q12hr

Intra-abdominal Infections

Mild to moderate: 250-500 mg IV q6hr

Severe: 500 mg IV q6hr or 1 g q8hr for 4-7 days, provided that infection is brought under control

Pseudomonas Infections

500 mg IV q6hr; higher dosages may be administered, depending on organism sensitivity

Urinary Tract Infections

Uncomplicated: 250 mg IV q6hr

Complicated: 500 mg IV q6hr

Dosing Considerations

Dosages are based on imipenem component

Dosages given are for patients weighing >70 kg; use lower dosages in patients weighing <70 kg

Susceptible organisms

  • Acinetobacter spp, Alcaligenes xylosoxidans, Bacteroides spp, Citrobacter spp, Clostridium spp, Enterobacter spp, Escherichia coli, Gardnerella vaginalis, Haemophilus influenzae, Haemophilus parainfluenzae, Klebsiella spp, Morganella morganii, Nocardia spp, Propionibacterium spp, Proteus vulgaris, Providencia rettgeri, Pseudomonas aeruginosa, Rhodococcus equi, Serratia marcescens, Staphylococcus aureus (penicillinase-producing), Staphylococcus epidermidis, enterococci, group B/D streptococci, Streptococcus pyogenes, Streptococcus pneumoniae

Mild infections (rarely used)

  • Fully susceptible organisms: 250 mg IV q6hr
  • Moderately susceptible organisms: 500 mg IV q6hr

Moderate infections

  • IV: Fully susceptible organisms: 500 mg IV q6-8hr
  • Moderately susceptible organisms: 500 mg IV q6hr or 1 g IV q8hr

Severe infections

  • Fully susceptible organisms: 500 mg IV q6hr
  • Moderately susceptible organisms: 1 g IV q6-8hr; not to exceed 50 mg/kg/day or 4 g/day, whichever is lower

Dosing Modifications

Renal impairment

  • CrCl ≥71 mL/min/1.73 m²: 250 mg IV q6hr
  • CrCl 41-70 mL/min/1.73m²: 250 mg IV q8hr
  • CrCl 21-40 mL/min/1.73 m²: 125-250 mg IV q12hr
  • CrCl ≤20 mL/min/1.73 m²: 125-250 mg IV q12hr
  • CrCl <5 mL/min/1.73 m²: Use IV only if hemodialysis is instituted within 48 hours
  • Hemodialysis: Give supplemental dose after each dialysis, then q12hr

Dosage Forms & Strengths

imipenem/cilastatin

powder for injection

  • 250mg/250mg
more...

Dosages based on imipenem component

<1 week, >1.5 kg: 25 mg/kg IV q12hr for non-CNS infections  

1-4 weeks, >1.5 kg: 25 mg/kg IV q8hr for non-CNS infections

4 weeks-3 months, >1.5 kg: 25 mg/kg IV q6hr for non-CNS infections

>3 months: 15-25 mg/kg IV q6hr for non-CNS infections; not to exceed 2 g/day for fully susceptible organisms or 4 g/day for moderately susceptible organisms

>12 years: 10-15 mg/kg IV q6hr for mild-to-moderate infections

Cystic fibrosis patients: Up to 100 mg/kg/day IV divided q6hr; not to exceed 4 g/day (in older children)

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Interactions

Interaction Checker

imipenem/cilastatin and

No Results

     
     activity indicator 
    No Interactions Found
    Interactions Found

    Contraindicated

      Serious - Use Alternative

        Significant - Monitor Closely

          Minor

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            Adverse Effects

            1-10%

            Phlebitis (2-5%)

            Eosinophilia (4%)

            Miscellaneous dermatologic effects (<3%)

            Potentially false-positive Coombs test (2%)

            Miscellaneous hematologic effects (<2%)

            Transient increase in blood urea nitrogen (BUN) or serum creatinine (<2%)

            Seizures (1.5%)

            Nausea, diarrhea, vomiting (1-2%)

            <1%

            Abnormal urinalysis

            Agitation

            Anaphylaxis

            Anemia

            Confusion (acute)

            Dizziness

            Dyskinesia

            Emergence of resistant strains of Pseudomonas aeruginosa

            Fever

            Hypersensitivity

            Hypotension

            Elevated liver function test (LFT) results

            Increased prothrombin time (PT)

            Neutropenia (including agranulocytosis)

            Palpitations

            Pruritus

            Pseudomembranous colitis

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            Warnings

            Contraindications

            Hypersensitivity to imipenem or cilastatin

            Cautions

            History of hypersensitivity to penicillins

            Use with caution in CNS disorders (eg., history of seizures); adjust dosage in renal impairment to avoid risk of seizures; carbapenem use has been associated with seizures

            Prolonged use increases risk of superinfections

            Use with caution in renal impairment; adjust dosage in moderate to severe renal dysfunction

            Carbapenem use may decrease serum levels of divalproex sodium or valproic acid

            Combination with aminoglycosides may thwart resistant P aeruginosa

            Not for use in children with CNS problems

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            Pregnancy & Lactation

            Pregnancy category: C

            Lactation: Drug distributed in breast milk; use with caution

            Pregnancy Categories

            A:Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

            B:May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

            C:Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

            D:Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

            X:Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

            NA:Information not available.

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            Pharmacology

            Mechanism of Action

            Imipenem inhibits bacterial cell-wall synthesis by binding to penicillin-binding proteins; cilastatin prevents renal metabolism of imipenem

            Distribution

            Distributed rapidly and widely to most tissues and fluids, including sputum, pleural fluid, peritoneal fluid, interstitial fluid, bile, aqueous humor, reproductive organs, and bone; highest concentrations in pleural fluid, interstitial fluid, peritoneal fluid, and reproductive organs; low concentrations in CSF; crosses placenta; enters breast milk

            Protein bound: Imipenem, 13-21%; cilastatin, 40%

            Metabolism

            Imipenem is metabolized in the kidney by dehydropeptidase 1; activity is blocked by cilastatin

            Elimination

            Half-life (both drugs): 60 min; prolonged with renal impairment

            Excretion (both drugs): Urine (~70% as unchanged drug)

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            Administration

            IV Incompatibilities

            Solution: D5/LR, LR, sodium bicarbonate, sodium lactate (D5W and NS causes some activity loss but are recommended for short-term use)

            Y-site: Allopurinol, amiodarone, amphotericin B cholesteryl sulfate, azithromycin, etoposide phosphate, fluconazole, gemcitabine, lorazepam, meperidine, midazolam, sargramostim, sodium bicarbonate

            IV Preparation

            Reconstitute infusion bottles with 100 mL of compatible diluent

            Reconstitute vials with a portion (usually 10 mL) of IV fluid withdawn from the IV container, dissolve, and return to container; repeat

            Reconstituted solutions are stable for 4 hours at room temperature and 24 hours refrigerated (4 C) in NS

            Normal color ranges from clear to yellow; these variations do not affect potency, but solution should be discarded if brown

            Imipenem is inactivated at acidic or alkaline pH

            IV Administration

            Do not administer by IV push

            Final concentration should not exceed 5 mg/mL

            Infuse ≤500 mg over 20-30 minutes (15-30 minutes in children); infuse >500 mg over 40-60 min

            Vial contents must be transferred to 100 mL of infusion solution

            If nausea or vomiting occurs during administration, reduce infusion rate

            Drug must not be mixed or physically added to other antibiotics; however, it may be administered concomitantly

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            Images

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            Formulary

            FormularyPatient Discounts

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            The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

            Tier Description
            1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
            2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
            3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
            4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            NC NOT COVERED – Drugs that are not covered by the plan.
            Code Definition
            PA Prior Authorization
            Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
            QL Quantity Limits
            Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
            ST Step Therapy
            Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
            OR Other Restrictions
            Drugs that have restrictions other than prior authorization, quantity limits, and step therapy associated with each prescription.
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