Imipenem-Cilastatin
Pronouncation: (ih-mih-PEN-em-SIGH-luh-STAT-in)
Class: Carbapenem
Trade Names:
Primaxin IV
- Powder for Injection 250 mg imipenem equivalent and 250 mg cilastatin equivalent. Contains 0.8 mEq sodium.
- Powder for Injection 500 mg imipenem equivalent and 500 mg cilastatin equivalent. Contains 1.6 mEq sodium.
Trade Names:
Primaxin IM
- Powder for Injection 500 mg imipenem equivalent and 500 mg cilastatin equivalent. Contains 1.4 mEq sodium.
- Powder for Injection 750 mg imipenem equivalent and 750 mg cilastatin equivalent. Contains 2.1 mEq sodium.
Mechanism of Action
Pharmacology
Imipenem inhibits bacterial cell wall synthesis. Cilastatin prevents metabolism of imipenem, resulting in increased urinary recovery and decreased renal toxicity.
Indications and Usage
Treatment of serious infections of lower respiratory tract and urinary tract, intra-abdominal and gynecologic infections, bacterial septicemia, bone and joint infections, skin and skin structure infections, endocarditis, and polymicrobic infections due to susceptible microorganisms.
Contraindications
IM use with hypersensitivity to local anesthetics of amide type or with severe shock or heart block.
IV use with patients with meningitis (safety and efficacy have not been established).
Dosage and Administration
Adults
IV 125, 250, or 500 mg dose over 20 to 30 min. Infuse a 750 mg or 1 g dose over 40 to 60 min. If nausea develops, slow the infusion rate. Max: 50 mg/kg/day or 4 g/day, whichever is lower.
Adults
IM 500 to 750 mg every 12 h. Max: 1,500 mg/day.
Children less than 40 kg
IM 60 mg/kg/day.
Children at least 40 kg
IM Adult dose.
Premature Infants (at least 36 wk Gestational Age)
IM 20 mg/kg every 12 h.
General Advice
- For IV administration, reconstitute with 100 mL of compatible diluent. Shake until suspension is clear; add suspension to 100 mL of appropriate infusion solution. Then add 10 mL of infusion to vial; shake well to ensure that all medication is used and transfer resulting suspension to infusion solution. Color of solution may range from colorless to yellow. Solution is stable for 4 h at room temperature and for 24 h when refrigerated. Do not administer if solution is cloudy.
- Do not mix with or physically add to antibiotics. However, it may be administered concomitantly with other antibiotics (eg, aminoglycosides).
- Do not use IM preparation for IV administration.
- For IM administration, prepare with 1% lidocaine HCl solution (without epinephrine). Prepare 500 mg vial with 2 mL and 750 mg vial with 3 mL of lidocaine. Agitate to form suspension. Color of solution may range from white to light tan. Withdraw and inject entire contents of vial IM. Use within 1 h of preparation.
Storage/Stability
Store unreconstituted powder at or below 77°F.
Drug Interactions
Cyclosporine
CNS side effects (eg, myoclonia, seizures) may be increased.
Ganciclovir
Generalized seizures may occur; avoid use.
Probenecid
Minimal increases in imipenem levels and half-life; do not give probenecid concurrently.
Incompatibility
Do not physically mix imipenem-cilastatin with other antibiotics.
Laboratory Test Interactions
May cause positive Coombs test results.
Adverse Reactions
Cardiovascular
Hypotension; palpitations; tachycardia; phlebitis; thrombophlebitis.
CNS
Seizures.
GI
Nausea; diarrhea; vomiting; pseudomembranous colitis; hemorrhagic colitis; hepatitis.
Genitourinary
Presence of RBCs, WBCs, casts, and bacteria in urine; increased BUN and creatinine.
Hematologic
Decreased Hgb and Hct; eosinophilia; increased or decreased WBCs and platelets; decreased erythrocytes.
Hepatic
Increased AST, ALT, alkaline phosphatase, and bilirubin.
Miscellaneous
Pain at injection site.
Precautions
Pregnancy
Category C .
Lactation
Undetermined.
Children
Safety and efficacy in children younger than 12 yr of age are not established with IM use. IV use in newborns to 16 yr of age (with non-CNS infections) is supported by evidence from adequate and well-controlled studies. IV use is not recommended in pediatric patients with CNS infections because of the risk of seizures, or in pediatric patients less than 30 kg with impaired renal function as no data are available.
Hypersensitivity
Administer drug with caution to penicillin-sensitive patients due to possible cross-activity.
Renal Function
Dosage reduction or alteration of dosage interval is required.
Superinfection
May result in bacterial or fungal overgrowth of nonsusceptible organisms.
Benzyl alcohol
Benzyl alcohol as a preservative has been associated with toxicity in newborns, especially those younger than 3 mo. Do not use diluents containing benzyl alcohol when IV is constituted for administration to pediatric patients.
CNS
IV administration may result in myoclonic activity confusional states or seizures.
Pseudomembranous colitis
Consider possibility in patients with diarrhea.
Overdosage
Symptoms
Seizures.
Patient Information
- Instruct patient to report the following to health care provider: itching; rash; hives; difficulty breathing; diarrhea; black “furry” tongue; loose, foul-smelling stools; vaginal itching or discharge.
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