IMIPENEM-CILASTATIN SODIUM

(i-mi-pen'em sye-la-stat'in)

Primaxin
Classifications: beta-lactam antibiotic;
Therapeutic: antibiotic
Pregnancy Category: C

Availability

250 mg, 500 mg vials

Action

Fixed combination of imipenem, a beta-lactam antibiotic, and cilastatin. Action of imipenem: inhibition of mucopeptide synthesis in bacterial cell walls leading to cell death. Cilastatin increases the serum halflife of imipenem.

Therapeutic Effect

Effectively used for severe or resistant infections. Acts synergistically with aminoglycoside antibiotics against some isolates of Pseudomonas aeruginosa. Infections resistant to cephalosporins, penicillins, and aminoglycosides have responded to treatment with this combination.

Uses

Treatment of serious infections caused by susceptible organisms in the urinary tract, lower respiratory tract, bones and joints, skin and skin structures; also intraabdominal, gynecologic, and mixed infections; bacterial septicemia and endocarditis.

Contraindications

Hypersensitivity to any component of product, multiple allergens; carbapenem hypersensitivity; penicillin hypersensitivity; pregnancy (category C).

Cautious Use

Patients with CNS disorders (e.g., seizures, brain lesions, history of recent head injury); seizures; renal failure, renal impairment, renal disease; patients with history of cephalosporin allergies; lactation.

Route & Dosage

Serious Infections
Adult: IV 250–500 mg infused over 20–30 min q6–8h IM 500 or 750 mg q12h
Child: IV >3 mo, 60–100 mg/kg/d in divided doses; 1–3 mo, 100 mg/kg/d in divided doses IM 15–25 mg/kg q12h
Neonate: IV <1 wk, 40–50 mg/kg/d in divided doses; >1 wk, 60–75 mg/kg/d in divided doses

Renal Impairment
Cl_cr 20–30 mL/min: dose q8–12h; <20 mL/min: dose q12h

Administration

Caution: IM and IV solutions are NOT interchangeable; do NOT give IM solution by IV, and do NOT give IV solution as IM.

Intramuscular

Reconstitute powder for IM injection as follows: Add 2 mL or 3 mL of 1% lidocaine HCl solution without epinephrine, respectively, to the 500 mg vial or the 750 mg vial. Agitate to form a suspension then withdraw and inject entire contents of the vial IM.
Give IM suspension by deep injection into the gluteal muscle or lateral thigh.
Use reconstituted IM injection within 1 h after preparation.

Intravenous

PREPARE: Intermittent: ??Dilute each dose with 10 mL of D5W, NS, or other compatible infusion solution.??Agitate the solution until clear. Color should range from colorless to yellow.??Further dilute with 100 mL of same solution used for initial dilution.

ADMINISTER: Intermittent: Give each 500 mg or fraction thereof over 20–30 min. DO NOT give as a bolus dose. Nausea appears to be related to infusion rate, and if it presents during infusion, slow the rate (occurs most frequently with 1-g doses).

INCOMPATIBILITIES Solution/additive: Ringer's lactate, some dextrose-containing solutions, sodium bicarbonate, TPN. Y-site: Allopurinol, aminodarone, amphotericin B cholesteryl, azithromycin, etoposide, fluconazole, gemcitabine, lorazepam, meperidine, midazolam, milrinone, sargramostim, sodium bicabonate.

Store according to manufacturer's recommendations; stability of IV solutions depends on diluent used for reconstitution.
Most IV solutions retain potency for 4 h at 15°–30° C (59°–86° F) or for 24 h if refrigerated at 4° C (39° F). Avoid freezing.

Adverse Effects (≥1%)

Body as a Whole: Hypersensitivity (rash, fever, chills, dyspnea, pruritus), weakness, oliguria/anuria, polyuria, polyarthralgia; phlebitis and pain at injection site, superinfections. CNS: Seizures, dizziness, confusion, somnolence, encephalopathy, myoclonus, tremors, paresthesia, headache. GI: Nausea, vomiting, diarrhea, pseudomembranous colitis, hemorrhagic colitis, gastroenteritis, abdominal pain, glossitis, heartburn. Respiratory: Chest discomfort, hyperventilation, dyspnea. Skin: Rash, pruritus, urticaria, candidiasis, flushing, increased sweating, skin texture change, facial edema. Metabolic: Hyponatremia, hyperkalemia. Special Senses: Transient hearing loss; increased WBC, AST, ALT, alkaline phosphatase, BUN, LDH, creatinine; decreased Hgb, Hct, eosinophilia.

Interactions

Drug: Aztreonam, cephalosporins, penicillins may antagonize the antibacterial effects. May affect cyclosporine levels.

Pharmacokinetics

Distribution: Widely distributed; limited concentrations in CSF; crosses placenta; in breast milk. Elimination: 70% in urine within 10 h. Half-Life: 1 h.

Nursing Implications

Assessment & Drug Effects

Determine previous hypersensitivity reaction to beta-lactam antibiotics (penicillins and cephalosporins) or to other allergens.
Monitor for S&S of hypersensitivity (see Appendix F). Discontinue drug and notify physician if S&S occur.
Monitor closely patients vulnerable to CNS adverse effects.
Notify physician if focal tremors, myoclonus, or seizures occur; dosage adjustment may be needed.
Monitor for S&S of superinfection (see Appendix F).
Notify physician promptly to rule out pseudomembranous enterocolitis if severe diarrhea accompanied by abdominal pain and fever occurs (see Appendix F).
Note: Sodium content derived from drug is high; consider in patient on restricted sodium intake.
Monitor renal, hematologic, and liver function periodically.

Patient & Family Education

Notify physician immediately to report pruritus or symptoms of respiratory distress.
Report pain or discomfort at IV infusion site.
Report loose stools or diarrhea promptly.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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