Ropinirole hydrochloride

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.

Repreve (GlaxoSmithKline)
0.25 mg, 0.5 mg and 2 mg film-coated tablets
Approved indication: restless legs syndrome
Australian Medicines Handbook section 16.2

Patients with restless legs syndrome are distressed by an irresistible urge to move their legs. They may also complain of crawling or burning sensations in their lower limbs. The symptoms are worst at night. In most cases there is no obvious cause, but patients may get relief with self-help techniques such as relaxation exercises.

As restless legs syndrome involves motor restlessness it follows that drugs for Parkinson's disease could have some effect. As levodopa can make the problem worse, there has been interest in dopamine agonists such as bromocriptine and pergolide. Ropinirole is a dopamine agonist which binds to the D2, D3 and D4 receptors and has been used to treat Parkinson's disease. In a crossover study of 22 patients with restless legs syndrome, ropinirole produced more relief than placebo. The main difference between ropinirole and placebo was 12 points on a rating scale of 0-40 points.¹ Larger studies show that after 12 weeks of treatment ropinirole will reduce a patient's score by 11 points while a placebo will reduce it by approximately 8.5 points.

If a patient's restless legs are so frequent and distressing that drug treatment is required then ropinirole can be considered.

It is taken once a day before bedtime and the dose is gradually increased over several weeks according to the patient's response.

The tablets are rapidly absorbed, but first-pass metabolism reduces the bioavailability to 46%. Ropinirole is metabolised in the liver and there is a potential for interactions with drugs, such as theophylline, ciprofloxacin and fluvoxamine, that are metabolised by or inhibit cytochrome P450 1A2. The drug has a half-life of six hours with most of the metabolites being excreted in the urine.

As dopamine receptors are not confined to the central nervous system, some of the adverse effects of ropinirole can be predicted. For example, peripheral dopaminergic effects can cause hypotension. Ropinirole should therefore be used cautiously in patients with cardiovascular disease. Nausea is the most frequent adverse reaction, affecting up to 38% of patients. Ropinirole can cause fatigue and some patients may suddenly fall asleep. Patients with somnolence are advised not to drive or operate machinery. Other adverse effects include dizziness, vomiting and nervousness.

Although some of the benefits of ropinirole could possibly be related to making people sleepy, it seems to have an advantage over placebo. There appear to be no direct comparisons of ropinirole with other dopamine agonists.

Note on references

At the time the comment was prepared, information about this drug was available on the web site of the Food and Drug Administration in the USA (www.fda.gov).