mercaptamine bitartrate: prescribing and clinical use
Focused clinical detail for use alongside current product information, local policy and patient-specific assessment.
mercaptamine bitartrate: clinical details
Prescribing considerations
- Confirm nephropathic cystinosis clinically and biochemically; initiate treatment under a clinician experienced in cystinosis.
- Start promptly after confirmation to maximise benefit.
- Do not assume conventional and gastro-resistant formulations are directly interchangeable without specialist assessment.
- Continue indicated ocular cysteamine because oral treatment does not prevent corneal crystal deposition.
- Assess unusual or changing abdominal symptoms, particularly with the gastro-resistant formulation.
- Consider aspiration risk before giving intact capsules to young children.
Contraindications and cautions
- Hypersensitivity to cysteamine, mercaptamine or formulation excipients
- Hypersensitivity to penicillamine
- Breastfeeding
- Pregnancy requires careful specialist reconsideration because of potential teratogenic risk
Monitoring
- White-cell cystine using assay-specific laboratory interpretation
- Full blood count and liver function
- Skin, joints and bones; investigate abnormalities where indicated
- Gastrointestinal ulceration, bleeding or unusual abdominal symptoms
- Neurological status and symptoms of intracranial hypertension; arrange eye assessment when indicated
- Tolerance and white-cell cystine particularly during dialysis, after transplantation or following a formulation change
Clinical pharmacology
Cysteamine forms a cysteamine–cysteine mixed disulphide with lysosomal cystine. This product and cysteine can leave the lysosome through transport systems unaffected by the cystinosin defect, reducing intracellular cystine.
Formulation and product differences
- Cystagon is a conventional hard capsule; taking it with or just after food may improve gastrointestinal tolerance.
- Procysbi contains gastro-resistant granules. They must not be crushed or chewed, and administration should be consistent in relation to food.
- The capsule contents may be opened for selected foods or feeding-tube administration, but permitted foods and handling instructions differ between formulations.
- Storage requirements differ: Procysbi requires refrigeration before opening and has specific in-use handling, while Cystagon is stored below its stated room-temperature limit and protected from moisture.
mercaptamine bitartrate preparations and strengths
Capsule
Route: Oral
Strengths: 25 mg, 50 mg, 75 mg, 150 mg
mercaptamine bitartrate interactions
Give the specialist and pharmacist a complete list of prescribed, non-prescribed and complementary products. Interaction evidence is limited and differs by formulation.
Bicarbonate replacement
Do not take bicarbonate at the same time as Procysbi because it may cause the gastro-resistant granules to release cysteamine too early; follow specialist timing instructions.
Medicines dependent on CYP enzymes or P-gp, BCRP, OATP or OCT transporters
Procysbi may theoretically alter exposure to some substrates of these pathways, although the clinical relevance is uncertain; review important concomitant medicines.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.