Imipenem-Cilastatin sodium
Imipenem-Cilastatin sodium (Primaxin)
Imipenem-Cilastatin sodium
(em-ee- PEN-em, sigh-lah- STAT-in)
Pregnancy Category: C Primaxin I.M. Primaxin I.V. (Rx)

Classification: Antibiotic combined with inhibitor of dehydropeptidase I

See Also: See also Anti-Infectives .

Content: The Powder for IV injection and the Powder for IM injection contain: imipenem, 500 mg, and cilastatin sodium, 500 mg, or imipenem, 750 mg, and cilastatin sodium, 750 mg.

Action/Kinetics: Inhibits cell wall synthesis. Is bactericidal against a wide range of gram-positive and gram-negative organisms. Stable in the presence of beta-lactamases. Addition of cilastatin prevents the metabolism of imipenem in the kidneys by dehydropeptidase I, thus ensuring high levels of the imipenem in the urinary tract. t 1/2, after IV: 1 hr for each component. Peak plasma levels of imipenem, after 20 min IV infusion: 14-24 mcg/mL for the 250-mg dose, 21-58 mcg/mL for the 500-mg dose, and 41-83 mcg/mL for the 1-g dose. Peak plasma levels, after IM: 10-12 mcg/mL within 2 hr. Compared with IV administration, imipenem is approximately 75% bioavailable after IM use with cilastatin being 95% bioavailable. t 1/2, imipenem: 2-3 hr. About 70% of imipenem and cilastin is recovered in the urine within 10 hr of administration.

Uses: IV: To treat the following serious infections: lower respiratory tract, urinary tract (complicated and uncomplicated), gynecologic, skin and skin structures, bone and joint, endocarditis, intra-abdominal, bacterial septicemia, and infections caused by more than one agent. Infections resistant to aminoglycosides, cephalosporins, or penicillins have responded to imipenem. Bacterial eradication may not be achieved in clients with cystic fibrosis, chronic pulmonary disease, and lower respiratory tract infections caused by Pseudomonas aeruginosa.
IM: This route of administration is not intended for severe or life-threatening infections (including endocarditis, or bacterial sepsis). Used for lower respiratory tract infections (including pneumonia and bronchitis), intra-abdominal infections, skin and skin structure infections, gynecologic infections.

Contraindications: IM use in clients allergic to local anesthetics of the amide type and use in clients with heart block (due to the use of lidocaine HCl diluent) or severe shock. Use in clients with a C _CR of less than or equal to 5 mL/min/1.73 m ², unless hemodialysis is begun within 48 hr. IV use in children with CNS infections due to the risk of seizures and in children less than 30 kg with impaired renal function.

Special Concerns: Use with caution in pregnancy and lactation. Due to cross sensitivity, use with caution in clients with penicillin allergy. Safety and effectiveness have not been determined for use IM in children less than 12 years of age.

Side Effects: GI: Pseudomembranous colitis nausea, diarrhea, vomiting, abdominal pain, heartburn, increased salivation, hemorrhagic colitis gastroenteritis, glossitis, pharyngeal pain, tongue papillar hypertrophy, hepatitis, jaundice, staining of the teeth or tongue. CNS: Fever, confusion, seizures dizziness, sleepiness, myoclonus, headache, vertigo, paresthesia, encephalopathy, tremor, psychic disturbances (including hallucinations). CV: Hypotension, tachycardia, palpitations. Dermatologic: Rash, urticaria, pruritus, flushing, cyanosis, facial edema, erythema multiforme, skin texture changes, hyperhidrosis, angioneurotic edema, toxic epidermal necrolysis, Stevens-Johnson syndrome. CV: Hypotension, palpitations, tachycardia. Respiratory: Chest discomport, dyspnea, hyperventilation. GU: Pruritus vulvae, anuria/oliguria, acute renal failure, polyuria, urine discoloration. Hematologic: Pancytopenia, bone marrow depression, thrombocytopenia, neutropenia, leukopenia, hemolytic anemia. Miscellaneous: Candidiasis, superinfection, tinnitus, polyarthralgia, asthenia, muscle weakness, transient hearing loss in clients with existing hearing impairment, taste perversion, thoracic spine pain.
Children, 3 months and older: Diarrhea, rash, phlebitis, gastroenteritis, vomiting, IV site irritation, urine discoloration. Children, newborn to 3 months: Convulsions, diarrhea, oliguria, anuria, oral candidiasis, rash, tachycardia.
The following side effects may occur at the injection site: Thrombophlebitis, phlebitis, pain, erythema, vein induration, infused vein infection.

Laboratory Test Alterations: IV: AST, ALT, alkaline phosphatase, bilirubin, LDH, BUN, creatinine, eosinophils, monocytes, lymphocytes, basophils, potassium, chloride. Neutrophils, hemoglobin, hematocrit. or WBCs, platelets. Positive Coombs' test and abnormal PT. Presence of protein, RBCs, WBCs, casts, bilirubin, or urobilinogen in the urine.
IM: AST, ALT, alkaline phosphatase, bilirubin, BUN, creatinine, PT. Hemoglobin, hematocrit, erythrocytes. or WBCs and platelets. Presence of RBCs, WBCs, casts, and bacteria in urine.

Drug Interactions: Cyclosporine / CNS side effects of both drugs Ganciclovir / Risk of generalized seizures Probenecid / Imipenem levels and half-life; do not use together

How Supplied: See Content

Dosage
?IV Fully susceptible gram-positive organisms, gram-negative organisms, anaerobes.
Mild: 250 mg q 6 hr; moderate: 500 mg q 6 hr or q 8 hr; severe/life-threatening: 500 mg q 6 hr.
Urinary tract infections due to fully susceptible organisms.
Uncomplicated: 250 mg q 6 hr; complicated: 500 mg q 6 hr.
Moderately susceptible organisms (especially some strains of P. aeruginosa).
Mild: 500 mg q 6 hr; moderate 500 mg q 6 hr to 1 g q 6 hr; severe/life-threatening 1 g q 6 or 8 hr.
Urinary tract infections due to moderately susceptible organisms.
Uncomplicated: 250 mg q 6 hr; complicated: 500 mg q 6 hr.
The total daily dose should not exceed 50 mg/kg or 4 g, whichever is lower.
Pediatric, non-CNS infections.
Children, 3 months of age or older: 15-25 mg/kg/dose q 6 hr, up to a maximum of dose of 2 g/day for treating infections with fully susceptible organisms and up to a maximum of 4 g/day for infections with moderately susceptible organisms. Doses as high as 90 mg/kg/day have been used in older children with cystic fibrosis. Children, three months of age or less (weighing 1,500 g or more): Less than 1 week of age, 25 mg/kg q 12 hr; 1-4 weeks of age, 25 mg/kg q 8 hr; 4 weeks to 3 months of age, 25 mg/kg q 6 hr. Give doses less than or equal to 500 mg by IV infusion over 15 to 20 min; give doses greater than 500 mg by IV infusion over 40 to 60 min.
?IM Lower respiratory tract, skin and skin structure, or gynecologic infections: mild to moderate.
500 or 750 mg q 12 hr depending on severity.
Intra-abdominal infections: mild to moderate.
750 mg q 12 hr. The total daily dose should not exceed 1.5 g.
Pediatric 3 months to 3 years, all uses: 15-25 mg/kg q 6 hr, to a maximum of 2 g/day. Pediatric, over 3 years, all uses: 15 mg/kg q 6 hr.