Some of the views expressed in the following notes on newly approved products should be regarded as preliminary, as there may have been limited published data at the time of publication, and little experience in Australia of their safety or efficacy. However, the Editorial Executive Committee believes that comments made in good faith at an early stage may still be of value. Before new drugs are prescribed, the Committee believes it is important that more detailed information is obtained from the manufacturer's approved product information, a drug information centre or some other appropriate source.
Trovan and Trovan IV (Pfizer)
200 mg tablets
40 mL and 60 mL vials containing 5mg/mL
Approved indication: specified infections
Australian Medicines Handbook Section 5.1.12
At a time when antibiotic use in Australia is declining, the range of quinolones has been expanded with the introduction of trovafloxacin.It acts like the other quinolones by inhibiting an enzyme essential in the replication of bacterial DNA.
Two formulations are available. The tablets are taken once a day, while the concentrate is diluted and then infused over one hour. This intravenous formulation contains alatrofloxacin which is the prodrug of trovafloxacin. Alatrofloxacin is used because it is more soluble than trovafloxacin. Some intravenous fluids, e.g. normal saline, are not suitable for diluting alatrofloxacin.
Trovafloxacin tablets have a bioavailability of 88%. This is not affected by food, but the tablets should not be taken with antacids. Morphine also reduces absorption. Trovafloxacin is widely distributed with concentrations in some tissues exceeding those in the plasma. Half the dose is excreted unchanged, while the rest is metabolised and excreted mainly in the faeces. The half-life is 11 hours, but the drug needs to be given only once a day.
There is a broad spectrum of antibacterial activity including both Gram positive and Gram negative organisms. Susceptible organisms includes treptococci, staphylococci, Escherichia coli, Haemophilus influenzae, Moraxellacatarrhalis, Neisseria gonorrhoea, Pseudomonas aeruginosa and Chlamydiapneumoniae. This profile enables trovafloxacin to be used in a wide variety of conditions. These include pneumonia, pelvic inflammatory disease, gonorrhoea, chlamydial cervicitis and infections of the skin and skin structures.
In clinical trials, 5% of patients discontinued treatment because of adverse events. The common adverse events are dizziness, headache and nausea. Trovafloxacin should be used cautiously in patients with neurological disorders, including cerebral atherosclerosis, as seizures can occur. The drug should be discontinued if a rash develops because of the risk of hypersensitivity reactions.
Trovafloxacin is not appropriate for common infections. For example, it should not be used to treat uncomplicated lower urinary tract infections unless resistance to other antibiotics has been proven. The quinolones are useful drugs for organisms that may be difficult to eradicate e.g. Pseudomonasaeruginosa. Their use should therefore be restricted in order to slow the development of resistant bacteria. Although experience with trovafloxacin is limited, a possible advantage is its metabolism. There is minimal involvement of the cytochrome P450 system, so the potential for interactions with drugs such as warfarin, cimetidine and theophylline may be reduced.
