Iobenguane sulfate

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.

MIBGen (ANSTO Radiopharmaceuticals)

vials containing 90-110 MBq/mL

Approved indication: tumour localisation

Iobenguane is meta-iodobenzylguanidine, an analogue of noradrenaline. Radio labelling the iodine (I123) in the molecule therefore enables investigation of the sympathetic nervous system. Iobenguane localises in the adrenal medulla so it can be used in diagnostic scintigraphy of phaeochromocytomas. It can also be used to locate ganglioneuroblastomas, ganglioneuromas and paragangliomas, and to detect end stage neuroblastomas.

Patients are given a slow intravenous injection. The radioactivity spreads around the body with a high uptake in hyperplastic adrenal glands. Most of the dose is excreted in the urine within four days.

In a trial involving 120 patients, radiolabelled iobenguane showed intense uptake in 21 of 24 phaeochromocytomas confined to the adrenals. The uptake was partly increased in the other three tumours, however partial uptake also occurred in 30% of the normal adrenal glands.1

In a preoperative study involving 16 patients with neuroblastoma, radio labelled iobenguane showed the primary tumour in 15 cases.2

Although radio labelled iobenguane is a sensitive technique its advantages over other imaging techniques and its role in diagnostic algorithms will need clarification.

At the time the comment was prepared, a scientific discussion about this drug was available on the web site of the European Agency for the Evaluation of Medicinal Products (