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.
Permax (Eli Lilly)
0.05 mg, 0.25 mg and 1 mg tablets
Indication: adjunct to levodopa therapy in Parkinson's disease
Parkinson's disease is associated with a deficiency of dopamine in the basalganglia. Patients who require treatment are often treated with levodopa, usually in combination with a decarboxylase inhibitor. During long-term therapy, complications can develop including a reduced responsiveness to levodopa. One approach to this problem is to introduce a drug which directly stimulates the dopamine receptors. One group of dopaminergic agonists are the ergolines e.g. bromocriptine.
Pergolide is an ergoline which is active at D1, and D2 receptors. Little is known about the pharmacokinetics of the drug as it is difficult to assay. The suppression of prolactin secretion has been used as an indicator of the drug's activity. A single dose will inhibit prolactin secretion for at least 24 hours, but any clinical benefits are not so prolonged. Usually the drug is taken 3 times a day.
Postural hypotension can occur, so it is important to begin treatment with a low dose. The dose is then increased every 3 days until an optimal level is reached. It may then be possible to reduce the concurrent dose of levodopa. The response to pergolide may decline with time requiring an increase in the dose, but the long-term efficacy of doses over 5 mg/day has not been evaluated.
Dopaminergic agonists can cause hallucinations, confusion, nausea and vomiting. Liver function and white blood cell counts should be monitored before and during pergolide treatment.
There are no convincing data to show a clinical advantage for any particular dopaminergic agonist. Information from overseas shows that pergolide is much more expensive than bromocriptine. Therefore, pergolide will probably only be used as an adjunctive treatment when the effect of levodopa therapy has declined and the patient does not respond to bromocriptine.
Data on the use of pergolide with levodopa-benserazide combinations are limited and there is insufficient evidence to allow pergolide to be approved for use as sole therapy in Parkinson's disease.