Cystagon

Dosage and administration of Cystagon

The standard dose strengths are 50 mg and 150 mg, in the form of capsules for oral administration only.

Necessary instruction for administration:

Start treatment with Cysteamine 50 mg immediately after diagnosis of nephropathic cystinosis. Start Cystagon at a fraction of the maintenance dosage.

• In patients 1-year-old to less than 12 years: dosing should be based on the body surface area. The recommended dose is 1.30 g/day of the free base divided 4 times daily.
• In the case of patients 12 years old and older and weigh more than 50 kg: the recommendation of Cystagon is 2 g/day, divided four times daily.

The only aim to start Cystagon dosage immediately after diagnosis is to keep leukocyte cystine levels below 1 nmol hemicystine per mg protein. Monitor the White blood cell (WBC) cystine levels to adjust the dose. Measure and frequently check the WBC levels 5-6 hours after dosing and when initiating therapy, for example monthly, and every 3-4 months when on a stable dose.

Initial doses should be 1/4 to 1/6 of the regular maintenance dose; increase the dosage slowly over 4- 6 weeks to avoid intolerance. Increase the dose amount if there is adequate tolerance and the leukocyte cystine level remains >1 nmol hemicystine per mg protein. The maximum dose of the Cystagon used in clinical trials was 1.95 g/day. Professionals do not recommend the use of doses higher than 1.95 g/m2 /day.

To improve the digestive tolerance of cysteamine, take medicine just after or with food.

• Children at risk of aspiration, aged approximately 6 years and under, administer the medicine by sprinkling the content of Cystagon 50 mg hard capsules over food. According to experience, the foods such as milk, potatoes, and other starch-based products seem appropriate for mixing with the powder. However, one should avoid acidic drinks as the powder tends not to mix well, and it will be left undissolved.
• Patients: dialysis or post-transplantation

According to experience, it is observed that some forms of cysteamine lead to more adverse events when patients are on dialysis. Healthcare professionals recommend closer monitoring of the leukocyte cystine levels in these patients.

• Patients with hepatic insufficiency

There is no necessity to adjust the dose generally; however, monitor the leukocyte cystine levels in such patients.

Overdosage

An overdose of cysteamine can cause progressive lethargy. If an overdose occurs, then one should support the respiratory and cardiovascular systems appropriately. No specific antidote is known. Removal of cysteamine is not known by hemodialysis.

Side effects: Common and Severe

Every medicine has some side effects, but everyone doesn’t need to experience them. Before taking medication, the patient should consult a doctor to prescribe doses according to the medical history of the patient. Doctors should acknowledge the patient of possible side effects of the drug.

Very Common
Vomiting, nausea, diarrhea, loss of appetite, fever, and sensation of sleep are very common side effects.

Common
Stomach and abdominal ache or discomfort, unpleasant breath, body odor, skin eruption, gastroenteritis, fatigue, headache, brain disorder, and liver function test abnormalities are common side effects.

Less frequent
Stretch marks, skin lesion (little-hard lumps on elbows), joint laxity, leg pain, bone fracture, scoliosis, bone deformity and fragility, hair discoloration, severe allergic reaction, drowsiness, fits, nervousness, hallucination, decrease in white blood cells, gastrointestinal ulcer indicated by bleeding in the digestive tract and effect on the kidney characterized by weight gain and
swelling of the extremities.

Precautions and Warnings

• Cystagon therapy must be started right after confirmation of the diagnosis of nephropathic cystinosis to achieve maximum benefit.
• Diagnose nephropathic cystinosis by both clinical signs and biochemical investigations (leukocyte cystine measurements). There are reports on cases of Ehlers-Danlos like syndrome and vascular disorders on elbows in children treated with heavy doses of different cysteamine preparations (cysteamine chlorhydrate or cystamine, or cysteamine bitartrate) mainly above the maximal amount of 1.95 g/m2 /day. The skin lesions are associated with vascular proliferation, stretch marks, and bone lesions. Therefore, professionals recommend regularly monitoring skin and considering X-ray examinations of the bone as necessary. Clinicians advise the self-examination of the skin by the patient or the parents. Doctors recommend the decrease of the dose if any similar skin or bone abnormalities appear. It is advised not to use doses higher than 1.95g/m2 /day.
• The doctors recommend monitoring blood cell count regularly.
• There is no evidence that Oral cysteamine prevents eye deposition of cystine crystals. Therefore, if the patient is using a cysteamine ophthalmic solution for that purpose, its usage should continue.
• In contrast to phospho cysteamine, Cystagon does not contain phosphate. Most patients might already be receiving phosphate supplements, and the dose of these might need to be altered when Cystagon is substituted for phospho cysteamine.
• Don’t administer hard capsules to children under the age of approximately 6 years due to the risk of aspiration.

Handling and storage of Cystagon

• Cystagon 50 mg: white, opaque hard capsules with Cysta 50 on the body and Mylan on the cap. Bottles of 100 or 500 hard pills.
• Cystagon 150 mg: white, opaque hard capsules with Cystagon 150 on the body and Mylan on the cap.Bottles of 100 or 500 hard pills.
• Do not store above 25°C, and to avoid light and moisture, keep the container tightly closed.
  Please do not use it after the expiry date mentioned on the label. The expiry date means the last day/month for consumption of the medicine.
• Keep the medicine Cystagon out of the reach and sight of children.