What is Procysbi - Mercaptamine used for?
Procysbi is a medicine that contains the active substance mercaptamine (also known as cysteamine) and is used in patients with nephropathic (kidney) cystinosis. Cystinosis is an inherited disease in which an excessive amount of cystine, an amino acid naturally present in the body, accumulates in cells, especially in the kidneys and eyes, damaging them. Because the number of cystinosis patients is low, the disease is considered "rare" and Procysbi was designated an "orphan medicine" (a medicine used in rare diseases) on September 20, 2010. Procysbi is a "hybrid medicine", meaning it is similar to a "reference medicine" containing the same active ingredient, but Procysbi is available in a formulation that allows a delayed release of the active ingredient in the body. The reference medicine for Procysbi is Cystagon.
How is Procysbi - Mercaptamine used?
Procysbi can only be obtained with a prescription and treatment should be started under the supervision of a doctor experienced in the treatment of cystinosis. Procysbi is available as gastroresistant capsules (25 and 75 mg). Gastroresistant means that the contents of the capsules pass through the stomach without being split until it reaches the intestine. The recommended daily dose is calculated based on the body surface, in the measure of 1.30 g per m2 divided into 2 doses administered every 12 hours. Cystine levels in white blood cells (which are measured as nmol of hemicystine per mg of protein in white blood cells), or alternatively the concentration of mercaptamine in the blood, must be monitored and used to regulate the dose, which must never exceed 1, 95 g per m2 per day. For more information, see the package leaflet.
How does Procysbi - Mercaptamine work?
The active ingredient in Procysbi, mercaptamine, reacts with cystine to form another amino acid, called cysteine, and a compound called the cysteine-cysteamine salt. The body is able to remove this salt from the cells. The amount of cystine in the organs is therefore reduced, and this limits the damage to these organs.
What benefit has Procysbi - Mercaptamine shown during the studies?
Procysbi administered every 12 hours has been shown to be at least effective when Cystagon is administered every 6 hours to keep the amount of cystine in white blood cells at acceptable levels (less than 1 nmol of hemicistine per mg of protein in white blood cells). In one main study involving 43 patients with nephropathic cystinosis, there was no significant difference between average cystine levels in white blood cells during a 3-week treatment with the two medicines. The levels were 0.51 nmol / mg with Procysbi, compared to 0.44 nmol / mg with Cystagon.
What is the risk associated with Procysbi - Mercaptamine?
The most common side effects with Procysbi (which may affect more than 1 in 10 people) are loss of appetite, vomiting, nausea (malaise), diarrhea, lethargy (lack of energy) and pyrexia (fever). For the full list of all side effects reported with Procysbi, see the package leaflet. Procysbi should not be used in people who are hypersensitive (allergic) to any form of mercaptamine to any of the other ingredients, or to penicillamine. It must also not be used in breast-feeding women.
Why has Procysbi - Mercaptamine been approved?
The Agency's Committee for Medicinal Products for Human Use (CHMP) decided that Procysbi's benefits are greater than its risks and recommended that it be approved for use in the EU. The CHMP noted that Procysbi has been shown to be at least as effective as Cystagon in maintaining the amount of cystine in white blood cells to an acceptable level. The Committee also considered that the gastroresistant formulation, due to its less frequent administration, is expected to increase treatment compliance and quality of life for cystinosis patients. Regarding its safety, the CHMP considered that the safety profile of mercaptamine is well established and that a safety similar to that of the reference medicine is expected for Procysbi.
What measures are being taken to ensure the safe and effective use of Procysbi - Mercaptamine?
A risk management plan has been developed to ensure that Procysbi is used as safely as possible. Based on this plan, safety information has been included in the summary of product characteristics and the package leaflet for Procysbi, including the appropriate precautions to be followed by healthcare professionals and patients.
In addition, the company that markets Procysbi will provide training material to all potential prescribers of the medicine, containing important safety information including the risk that the medicine is harmful to the unborn child.
More information on Procysbi - Mercaptamine
On 06.09.2013 the European Commission issued a marketing authorization for Procysbi, valid throughout the European Union. The full EPAR for Procysbi can be found on the Agency's website: ema.Europa.eu/Find medicine / Human medicines / European public assessment reports. For more information about treatment with Procysbi, read the package leaflet (also part of the EPAR) or contact your doctor or pharmacist. The summary of the opinion of the Committee for Orphan Medicinal Products for Procysbi is available on the Agency's website: ema.Europa.eu/Find medicine / Human medicines / Rare disease designation. Last update of this summary: 09-2013.
