Outpatient parenteral treatment of bacterial infections: the Italian model as an international trend?

The choice of administration route for an antibiotic remains a fairly controversial matter, as confirmed by the variation in prescribing habits among different countries. This variation may result from difficulty in identifying standard criteria that would unequivocally indicate the necessity of oral or parenteral administration. 1 In general, the decision to administer an antibiotic by the parenteral route is influenced by three main factors: (i) reduced gastrointestinal absorption in the patient; (ii) lack of appropriate oral antibiotics ; and (iii) specific disease and related severity. Although relatively rare, gastrectomy and short-bowel syndrome are the main gastrointestinal conditions that make oral administration impossible. Diarrhoea, nausea and vomiting are the most frequently observed gastrointestinal side effects that occur as a result of oral administration of an antibiotic; these disturbances can be responsible for impaired absorption. 2 Such side effects vary greatly in incidence and intensity according to the class of antibiotic used, but they should never be underestimated as they may lead to reduced compliance and/or gastrointestinal absorption which modifies the bioavailability of the drug and so may affect the outcome of treatment. For example, it has been reported that about 10% of 32 000 patients treated with co-amoxiclav, one of the most commonly prescribed antibiotics worldwide in an outpatient setting, experienced a gastrointestinal disorder. 3 Aminoglycosides, carbapenems and glycopeptides are the main classes of antibiotics for which no oral formulation is available. Whenever aetiology and/or clinical considerations make their use mandatory, the parenteral route of administration is unavoidable. Because of the risk of early complications, parenteral antibiotic therapy is always necessary from the outset in some infections such as endocarditis, osteomyelitis or meningitis, but in general the choice of parenteral therapy is reserved for more severe infections. This is in accordance with the belief that an injectable antibiotic, especially when used intravenously, guarantees rapid achievement of high blood concentrations, whereas oral administration does not. 4 However, many drugs are absorbed very well, so adequate blood concentrations can be achieved by oral administration. More recently, MacGregor & Graziani have proposed that, for serious infections, oral administration of antibiotics, especially at high doses, can offer a rational alternative to the parenteral route. 5 However, they failed to point out that the incidence and severity of gastrointestinal side effects are important drawbacks of such a practice. Choice of the parenteral route remains an empirical and individual decision which is generally associated with hospitalization. 6 …