McKenna's Pharmacology for Nursing, 2e

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P A R T 2  Chemotherapeutic agents

TABLE 9.2

DRUGS IN FOCUS Carbapenems

Drug name

Dosage/route

Usual indications

doripenem (Doribax)

500 mg IV, over 1 hour every 8 hour for 5–14 days

Treatment of complicated intraabdominal infections or complicated UTIs, including pyelonephritis, caused by susceptible bacteria Treatment of community acquired pneumonia, complicated GU infections, acute pelvic infections, complicated intra-abdominal infections, skin and skin structure infections Treatment of serious respiratory, intra- abdominal, urinary tract, gynaecological, bone and joint, skin and skin structure infections; septicaemia, endocarditis, bone and joint infections, and polymicrobic infections Treatment of respiratory tract infection, complicated urinary tract infection, febrile neutropenia, intra-abdominal and gynaecological infections, complicated skin infections, meningitis, septicaemia where there is resistance to commonly used antibiotics

1 g/day IV or IM for 5–14 days

ertapenem (Invanz)

imipenem-cilastatin (Primaxin)

250–500 mg IV q 6–8 hours or 500–750 mg IM q 12 hours Paediatric: <40 kg and >3 months: 15 mg/kg/day IV q 6 hours

meropenem (Merrem I.V.)

500 mg–1 g IV, q 8 hours

Imipenem-cilastatin is a combination of imipenem, which interferes with cell wall synthesis and causes bacterial cell death, and cilastin, which inactivates the imipenem and leads to increased urinary excretion of the drug and decreased renal toxicity. It can be given IM or IV and is approved for use in children. Meropenem is given IV every 8 hours by either bolus over 5 minutes or IV infusion over 15–30 minutes. Contraindications and cautions Carbapenems are contraindicated in the following con- ditions: known allergy to any of the carbapenems or beta-lactams ; seizure disorders, which could be exacer- bated by the drug ; meningitis, because safety in people with meningitis has not been established ; breastfeed- ing, because it is not known whether these drugs enter breast milk, but potentially they could cause serious effects in the infant. Use caution during pregnancy because carbapenems are used to treat only severe infections, and the benefits of the drug must be carefully weighed against potential adverse effects on the fetus. Test urine function regu- larly when these drugs are used because they depend on the kidney for excretion and are toxic to the kidney. Ertapenem is not recommended for use in people younger than 18 years of age. Adverse effects Toxic effects on the GI tract can limit the use of carb­ apenems in some people. Pseudomembranous colitis, Clostridium difficile diarrhoea and nausea and vomiting

can lead to serious dehydration and electrolyte imbal- ances, as well as to new serious infections. Superinfections can occur with any of the carb­ apenems. Closely monitor to deal with the new infection before it becomes overwhelming. CNS effects can include headache, dizziness and altered mental state. Seizures have been reported when carbapenems are combined with other drugs. Monitor people to provide safety measures if any of these occur. Prototype summary: Ertapenem Indications: Treatment of community-acquired pneumonia, complicated GU infections, complicated intraabdominal infections, skin and skin structure infections, and acute pelvic infections caused by susceptible bacteria. Actions: Inhibits protein synthesis in susceptible strains of gram-negative bacteria, disrupting functional integrity of the cell membrane and

causing cell death. Pharmacokinetics: Route

Onset Rapid

Peak

IM, IV

30–120 minutes

T 1/2 : 4 hours; excreted unchanged in the urine. Adverse effects: Headache, dizziness, nausea, vomiting, pseudomembranous colitis, rash, pain at injection site.