EU/3/12/1084: Orphan designation for the treatment of lead toxicity

Lead toxicity can occur when a person has been exposed to lead which can be found in the environment mainly due to its uses in industry and industrial processes. Exposure can occur from contact with lead in air, household dust, soil, water and commercial products.

Lead toxicity can lead to symptoms affecting many organs and body systems, including the heart, gut, kidneys, bones and reproductive and nervous system. Acute toxicity can result in pain, nausea, vomiting, diarrhoea, constipation and muscle weakness. Long-term exposure to lead commonly results in loss of memory or concentration, depression, nausea, abdominal pain, problems with sleep and headache. In the most severe cases, lead toxicity can cause seizures (fits) and coma and may lead to death.

Lead toxicity is a long-term debilitating and life-threatening condition due to interference with several body processes and damage to organs and body systems.

At the time of designation, lead toxicity affected approximately 0.23 in 10,000 people in the European Union (EU)*. This is equivalent to a total of around 12,000 people, and is below the ceiling for orphan designation, which is 5 people in 10,000. This is based on the information provided by the sponsor and the knowledge of the Committee for Orphan Medicinal Products (COMP).

*Disclaimer: For the purpose of the designation, the number of patients affected by the condition is estimated and assessed on the basis of data from the European Union (EU 27), Norway, Iceland and Liechtenstein. This represents a population of 506,300,000 (Eurostat 2011).

At the time of designation, several medicines were authorised in the EU to treat lead toxicity, such as ethylenediaminetetraacetic acid (EDTA), dimercaprol, D-penicillamine, 2,3-dimercaptosuccinic acid (DMSA) and 2,3 dimercapto-1-propane sulfonic acid (DMPS). These medicines are 'chelating' agents: they work by attaching to lead to form a compound that can be more easily excreted from the body.

The sponsor has provided sufficient information to show that erdosteine might be of significant benefit for patients with lead toxicity, because early studies show that it may be more effective than currently approved medicines at treating this condition. This assumption will need to be confirmed at the time of marketing authorisation, in order to maintain the orphan status.

Erdosteine is already authorised for use as a mucolytic (an agent which dissolves thick mucus). It is not understood how erdosteine would work in lead toxicity, but based on early studies it is expected to increase the excretion of lead through the urine when given to patients with lead toxicity.

At the time of submission of the application for orphan designation, the evaluation of the effects of erdosteine in experimental models was ongoing.

At the time of submission, no clinical trials with erdosteine in patients with lead toxicity had been started.

At the time of submission, erdosteine was not authorised anywhere in the EU for lead toxicity or designated as an orphan medicinal product elsewhere for this condition.

In accordance with Regulation (EC) No 141/2000 of 16 December 1999, the COMP adopted a positive opinion on 7 November 2012 recommending the granting of this designation.

• the seriousness of the condition;
• the existence of alternative methods of diagnosis, prevention or treatment;
• either the rarity of the condition (affecting not more than 5 in 10,000 people in the EU) or insufficient returns on investment.

Designated orphan medicinal products are products that are still under investigation and are considered for orphan designation on the basis of potential activity. An orphan designation is not a marketing authorisation. As a consequence, demonstration of quality, safety and efficacy is necessary before a product can be granted a marketing authorisation.