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.
Luvox (Solvay Pharmaceuticals)
100 mg tablets
Indication: depression, obsessive compulsive disorder
Fluvoxamine is a selective serotonin reuptake inhibitor (SSRI) which has been available overseas for at least 10 years. Its chemical structure is different to that of the other SSRIs.
The usual starting dose is 50 mg. This is well absorbed even in the presence of food. Fluvoxamine has a bioavailability of 53% as it is extensively metabolised by the liver. Most of the metabolites are inactive and excreted in the urine. If the drug is given to patients with renal or hepatic impairment, the dose should only be increased slowly. In healthy people taking repeated doses, the half-life is approximately 22 hours. Unless the treatment exceeds 150 mg per day, a single daily dose can be prescribed.
Fluvoxamine has mainly been compared with placebo or imipramine in studies of depression. It is unclear how fluvoxamine compares with other SSRIs. Most of the studies have only lasted for approximately 6 weeks. In general, the response to fluvoxamine will be greater than to placebo and similar to the response to imipramine. Patients who respond to fluvoxamine and continue to take it for up to a year are less likely to relapse than those who are switched to placebo.
Obsessive-compulsive disorder is difficult to treat.1 Fluvoxamine has been studied for this disorder in comparison with placebo or clomipramine. Significantly more patients responded to fluvoxamine than placebo and the effectiveness of fluvoxamine was similar to that of clomipramine.
The dose of fluvoxamine is increased until a response occurs. Nausea is a common complaint when starting treatment, but may decline over two weeks. The maximum dose is 300 mg.
After nausea, the most frequent adverse effects are headache, somnolence and insomnia. Other common adverse reactions include dry mouth, dizziness, asthenia, diarrhoea, constipation, palpitations and sweating. Rare events include convulsions, postural hypotension and abnormal liver function.
Fluvoxamine can inhibit the metabolism of other drugs metabolised in the liver. It can interact with carbamazepine, warfarin, phenytoin and oxidatively metabolised benzodiazepines.
- O'Sullivan BT, Johnson GF. The management of obsessive-compulsive disorder. Aust Prescr 1990;13:6-9.