Cost-Effectiveness and Value of an IV Switch

Summary

A few antibiotics (i.e. metronidazole, clindamycin and ciprofloxacin) are available in both parenteral and oral formulations, and have good bioavailability, ensuring equivalent systemic drug concentrations. During a 4-year period subsequent to the initiation of a parenteral to oral (IV-PO) stepdown programme for metronidazole and clindamycin, Vancouver General Hospital saved approximately $C85 000. However, many parenteral antibacterials lack an oral formulation, requiring oral stepdown to a different antibacterial with a similar spectrum of activity. Alternatively, the oral formulation of a parenteral antibacterial may have poor bioavailability (i.e. cefuroxime axetil, ampicillin, cloxacillin, erythromycin, and tetracycline) and it is not possible to maintain equivalent systemic drug concentrations. While rigid criteria are not applicable to all clinical scenarios, the general criteria for oral stepdown include the following: the patient 1) continues to need an antibiotic; 2) is clinically stable; 3) is capable of tolerating the oral dosage form; and 4) has no factors present (e.g. gastrointestinal abnormalities or drug interactions) that would adversely affect oral bioavailability. A review of subsequent IV-PO stepdown programmes at Vancouver General Hospital revealed that 1) not all patients receiving parenteral therapy are candidates for oral stepdown; 2) oral stepdown is delayed in a large proportion of treatment courses; 3) oral stepdown is not occurring in many patients for whom it is deemed appropriate; and 4) in a very few treatment courses stepdown may occur prematurely and may contribute to clinical deterioration. In 1991, acquisition costs for ceftriaxone, ceftazidime, and imipenem amounted to $C810 000, which represented 34% of total antibacterial drug expenses at Vancouver General Hospital. Cefixime, the first oral third generation cephalosporin marketed in Canada, can be used for oral stepdown in selected patients receiving ceftriaxone, ceftazidime, or ceftizoxime, resulting in decreased acquisition and delivery costs. Cefixime has been shown to be effective in the treatment of urinary tract infections, upper and lower respiratory tract infections, bacterial sinusitis and otitis media caused by susceptible pathogens; however, inadequate cerebrospinal fluid penetration precludes its use for the treatment of meningitis, and it lacks dependable activity against Pseudomonas aeruginosa, Staphylococcus aureus, and anaerobes. When applied judiciously, IV-PO stepdown can dramatically impact upon drug, drug delivery, and hospitalisation costs, lessen the incidence of IV-associated complications (e.g. phlebitis, infection), and facilitate early discharge.