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.
Raxar (Glaxo Wellcome)
600 mg tablets
Approved indication: specified infections
Australian Medicines Handbook Section 5.1.12
Grepafloxacin is a broad spectrum fluoroquinolone antibiotic. It has been approved for use in uncomplicated gonorrhoea, urethritis and cervicitis caused by Chlamydia trachomatis, acute bacterial exacerbations of chronic bronchitis and community-acquired pneumonia.
The dose of grepafloxacin depends on the condition being treated. Uncomplicated gonorrhoea can be treated with a single dose, while patients with chest infections can be treated for up to 10 days.
The absorption of the daily dose is not affected by food. The average plasma elimination half-life is 12 hours with most of the drug being cleared by the liver. Only 5-14% is excreted unchanged in the urine. Moderate or severe liver impairment is therefore a contraindication to grepafloxacin. As the metabolism of grepafloxacin involves cytochrome P450 (CYP1A2), there is a potential for interaction with drugs such as theophylline and caffeine.
The most common adverse reactions are nausea, altered taste, headache and dizziness. Grepafloxacin is a weak photosensitiser; this may be relevant in the Australian climate. As grepafloxacin can prolong the QT interval, it must not be given to patients who are taking medications which have a similar cardiac effect e.g. terfenadine, tricyclic antidepressants and some antipsychotics.
As there is concern about the development of antibiotic resistance, the fluoroquinolones should be used sparingly. Although studies have found grepafloxacin to have efficacy in its approved indications, it would not be the first-choice treatment. For example, the Antibiotic Guidelines1 recommend amoxycillin or doxycycline if treatment is needed for an exacerbation of chronic bronchitis. Prescribing a fluoroquinolone for such a common clinical condition risks increasing the problems of antibiotic resistance.
- Writing Group for Therapeutic Guidelines: Antibiotic. Therapeutic guidelines: antibiotic. 10th ed. Melbourne: Therapeutic Guidelines Limited; 1998.