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.

Moxifloxacin hydrochloride

Avelox (Bayer)
400 mg tablets
Approved indication: respiratory infections
Australian Medicines Handbook Section 5.1.12

Moxifloxacin is a fluoroquinolone antibiotic. Like other fluoroquinolones it is active against Gram-negative bacteria such as Haemophilus influenzae.Compared to older members of the class, such as ciprofloxacin, moxifloxacin has more activity against Gram-positive bacteria such as Streptococcus pneumoniae.

Given its spectrum of antibacterial activity moxifloxacin has been approved for the treatment of community-acquired pneumonia, exacerbations of chronic bronchitis and sinusitis. In studies of patients with community-acquired pneumonia, moxifloxacin has been as effective as other drugs such as clarithromycin.

Moxifloxacin is as effective as cefuroxime in the treatment of acute maxillarysinusitis. Cefuroxime was also equivalent to moxifloxacin in the treatment of exacerbations of chronic bronchitis. For this indication, a five day course of moxifloxacin is as effective as a seven day course of clarithromycin.

Moxifloxacin has a half-life of 12 hours, but can be given once a day. It is eliminated by renal and hepatic clearance. The metabolism of moxifloxacin does not involve the cytochrome P450 system. Although it has not been associated with the severe liver problems associated with trovafloxacin, moxifloxacin should not be given to patients with significant hepatic impairment.

Like other oral antibiotics, nausea, vomiting and diarrhoea are common adverse effects of moxifloxacin. It may cause dizziness and lightheadedness so patients should know how they react to this drug before they drive or operate machinery. Moxifloxacin can also prolong the QT interval so there is a potential for arrhythmias. Similar ECG changes led to the withdrawal of grepafloxacin. Moxifloxacin should therefore not be given to patients with a prolonged QTc interval, hypokalaemia, or those taking drugs which prolong the QTc interval. Although the photosensitivity potential of moxifloxacin appears to be low, hypersensitivity reactions can occur after the first dose.

Bacteria are becoming resistant to the fluoroquinolones and there is cross-resistance to drugs within the class. To maintain the usefulness of these drugs, moxifloxacin should probably not be used as a first-line treatment for common infections such as sinusitis.