Drugs List

Therapeutic Indications

Uses

Treatment of nephropathic cystinosis

Administration

For oral administration.

Mercaptamine is best tolerated if taken with or just after food, however, mercaptamine should not be administered with food rich in fat or proteins, or with frozen food like ice-cream.

Due to the risk of aspiration, children under 6 years of age should not be administered intact capsules. Open the capsule and sprinkle the contents on food. See relevant product information for further information on suggested foods and drinks.

Contraindications

Breastfeeding
Pregnancy

Precautions and Warnings

Children under 6 years
Kidney transplantation
Renal dialysis

Oral cysteamine has not been shown to prevent cystine crystals in the eye
Advise patient drowsiness may affect ability to drive or operate machinery
Treatment to be initiated and supervised by a specialist
Perform eye tests before treatment and regularly during treatment
Monitor blood values and liver function regularly
Monitor leucocyte cystine levels regularly
Monitor the skin and bone regularly
Advise patient to report sudden severe headache and visual disturbances
Advise patient to report unexplained nausea,vomiting,abdominal pain
Discontinue if severe skin reaction occurs
Bioavailability differs with preparations;caution on changing formulations
Dosage of phosphate supplements may need adjusting
Avoid bicarbonate within 1 hour before or 1 hour after the dose

Start treatment as soon as cystinosis is confirmed by clinical signs and biochemical tests (leucocyte cystine measurements), as early treatment initiation delays the development of renal failure.

Administration of mercaptamine ophthalmic solution should be continued where necessary to prevent eye deposition of cystine crystals.

Perform a periodic eye examination in order to identify benign intracranial hypertension (or pseudotumor cerebri) and/or papilledema early and so prevent vision loss by providing timely treatment.

Dosage of phosphate supplements may need adjusting when mercaptamine is substituted for phosphocysteamine.

Cases of Ehlers-Danlos like syndrome on elbows have been reported in children treated with high doses (mostly above 1.95g/square metre/day) of different mercaptamine preparations (mercaptamine chlorhydrate or cystamine or mercaptamine bitartrate). These skin lesions associated with skin striae and bone lesions which were identified during X-ray examination.

Patients on dialysis or post transplantation should have leucocyte cystine levels monitored more closely during therapy as some forms of mercaptamine are less well tolerated when patients are receiving dialysis.

Patients with hepatic impairment should have leucocyte cystine levels closely monitored during therapy.

Pregnancy and Lactation

Pregnancy

Mercaptamine is contraindicated in pregnancy.

Animal studies have shown reproductive toxicity, including teratogenesis. The risk for humans is unknown. The effect of untreated cystinosis in human pregnancy is also unknown.

The use of all medication in pregnancy should be avoided whenever possible; particularly in the first trimester. Non-drug treatments should also be considered. When essential, a medication with the best safety record over time should be chosen, employing the lowest effective dose for the shortest possible time. Polypharmacy should be avoided. Teratogens taken in the pre-embryonic period, often quoted as lasting until 14 to 17 days post-conception, are believed to have an all-or-nothing effect. Where drugs have a short half-life, and when the date of conception is certain, this may allow women to be reassured where drug exposure has occurred within this time frame. Further advice may be available from the UK National Teratology Information Service (NTIS) and through ToxBase, available via password on the internet ( www.toxbase.org ) or if this is unavailable at the backup site ( www.toxbasebackup.org ).

Lactation

Mercaptamine is contraindicated in breastfeeding.

It is not known whether mercaptamine is excreted in human breast milk. High doses of mercaptamine impair the ability of lactating rats to feed their pups. Single doses of the drug inhibit prolactin secretion in animals. Administration of mercaptamine in neonate rats induced cataracts.

Neonates, infants born prematurely, those with low birth weight, those with an unstable gastrointestinal function or who have serious illnesses may require special consideration. For any infant, if a drug is prescribed to the nursing mother, it should be at the lowest practical dose and for the shortest time. When drug administration is unavoidable and breastfeeding is to continue, minimisation of exposure of the infant to the drug may sometimes be achieved by timing the maternal doses to just after a feeding episode. Infants exposed to drugs via breast milk should be monitored for unusual signs or symptoms. Interactions between the drug received by the infant from the mother's milk and medication prescribed for the infant should also be considered, for example, when the drug given to the infant may prevent metabolism of the drug received via breast milk.
Specialist advice is available from the UK Drugs in Lactation Advisory Service at https://www.midlandsmedicines.nhs.uk/content.asp?section=6&subsection=17&pageIdx=1

Side Effects

Abdominal pain
Abnormal liver function tests
Anaphylactic reaction
Anorexia
Asthenia
Benign intracranial hypertension
Convulsions
Diarrhoea
Discolouration of hair
Dyspepsia
Ehlers-Danlos like syndrome (in children)
Encephalopathy
Epidermal fragility
Gastro-enteritis
Gastro-intestinal ulceration
Genu valgum
Hallucinations
Headache
Joint hyperextension
Leg pain
Lethargy
Leucopenia
Nausea
Nephrotic syndrome
Nervousness
Osteopenia
Papilloedema
Pyrexia
Rash
Scoliosis progression
Skin odour changes
Somnolence
Striae
Unpleasant breath
Vertebral compression fractures
Vomiting

Presentation

Oral formulations containing mercaptamine as mercaptamine bitartrate.

Drugs List

Therapeutic Indications

Uses

Treatment of nephropathic cystinosis

Dosage

The aim of therapy is to keep leucocyte cystine levels below 1nanomol hemicystine/mg protein. The white blood cell (WBC) cystine levels should be monitored to adjust the dose.

Adults

Children

Additional Dosage Information

Administration

For oral administration.

Mercaptamine is best tolerated if taken with or just after food, however, mercaptamine should not be administered with food rich in fat or proteins, or with frozen food like ice-cream.

Due to the risk of aspiration, children under 6 years of age should not be administered intact capsules. Open the capsule and sprinkle the contents on food. See relevant product information for further information on suggested foods and drinks.

Contraindications

Breastfeeding
Pregnancy

Precautions and Warnings

Children under 6 years
Kidney transplantation
Renal dialysis

Oral cysteamine has not been shown to prevent cystine crystals in the eye
Advise patient drowsiness may affect ability to drive or operate machinery
Treatment to be initiated and supervised by a specialist
Perform eye tests before treatment and regularly during treatment
Monitor blood values and liver function regularly
Monitor leucocyte cystine levels regularly
Monitor the skin and bone regularly
Advise patient to report sudden severe headache and visual disturbances
Advise patient to report unexplained nausea,vomiting,abdominal pain
Discontinue if severe skin reaction occurs
Bioavailability differs with preparations;caution on changing formulations
Dosage of phosphate supplements may need adjusting
Avoid bicarbonate within 1 hour before or 1 hour after the dose

Start treatment as soon as cystinosis is confirmed by clinical signs and biochemical tests (leucocyte cystine measurements), as early treatment initiation delays the development of renal failure.

Administration of mercaptamine ophthalmic solution should be continued where necessary to prevent eye deposition of cystine crystals.

Perform a periodic eye examination in order to identify benign intracranial hypertension (or pseudotumor cerebri) and/or papilledema early and so prevent vision loss by providing timely treatment.

Dosage of phosphate supplements may need adjusting when mercaptamine is substituted for phosphocysteamine.

Cases of Ehlers-Danlos like syndrome on elbows have been reported in children treated with high doses (mostly above 1.95g/square metre/day) of different mercaptamine preparations (mercaptamine chlorhydrate or cystamine or mercaptamine bitartrate). These skin lesions associated with skin striae and bone lesions which were identified during X-ray examination.

Patients on dialysis or post transplantation should have leucocyte cystine levels monitored more closely during therapy as some forms of mercaptamine are less well tolerated when patients are receiving dialysis.

Patients with hepatic impairment should have leucocyte cystine levels closely monitored during therapy.

Pregnancy and Lactation

Pregnancy

Mercaptamine is contraindicated in pregnancy.

Animal studies have shown reproductive toxicity, including teratogenesis. The risk for humans is unknown. The effect of untreated cystinosis in human pregnancy is also unknown.

The use of all medication in pregnancy should be avoided whenever possible; particularly in the first trimester. Non-drug treatments should also be considered. When essential, a medication with the best safety record over time should be chosen, employing the lowest effective dose for the shortest possible time. Polypharmacy should be avoided. Teratogens taken in the pre-embryonic period, often quoted as lasting until 14 to 17 days post-conception, are believed to have an all-or-nothing effect. Where drugs have a short half-life, and when the date of conception is certain, this may allow women to be reassured where drug exposure has occurred within this time frame. Further advice may be available from the UK National Teratology Information Service (NTIS) and through ToxBase, available via password on the internet ( www.toxbase.org ) or if this is unavailable at the backup site ( www.toxbasebackup.org ).

Lactation

Mercaptamine is contraindicated in breastfeeding.

It is not known whether mercaptamine is excreted in human breast milk. High doses of mercaptamine impair the ability of lactating rats to feed their pups. Single doses of the drug inhibit prolactin secretion in animals. Administration of mercaptamine in neonate rats induced cataracts.

Neonates, infants born prematurely, those with low birth weight, those with an unstable gastrointestinal function or who have serious illnesses may require special consideration. For any infant, if a drug is prescribed to the nursing mother, it should be at the lowest practical dose and for the shortest time. When drug administration is unavoidable and breastfeeding is to continue, minimisation of exposure of the infant to the drug may sometimes be achieved by timing the maternal doses to just after a feeding episode. Infants exposed to drugs via breast milk should be monitored for unusual signs or symptoms. Interactions between the drug received by the infant from the mother's milk and medication prescribed for the infant should also be considered, for example, when the drug given to the infant may prevent metabolism of the drug received via breast milk.
Specialist advice is available from the UK Drugs in Lactation Advisory Service at https://www.midlandsmedicines.nhs.uk/content.asp?section=6&subsection=17&pageIdx=1

Counselling

Advise patient to take mercaptamine with or just after food, however, mercaptamine should not be administered with food rich in fat or proteins, or with frozen food like ice-cream.

When administering to children under 6 years of age, the capsule(s) should be opened and the contents sprinkled on food.

Advise parents to monitor skin regularly in children as Ehlers-Danlos like syndrome associated with skin and bone lesions has been reported with mercaptamine preparations.

Advise patient to inform physician if signs or symptoms of serious gastrointestinal toxicity.

Advise patient that if CNS symptoms develop that they should not take part in potentially hazardous activities until the effects of mercaptamine on mental performance are known.

Side Effects

Abdominal pain
Abnormal liver function tests
Anaphylactic reaction
Anorexia
Asthenia
Benign intracranial hypertension
Convulsions
Diarrhoea
Discolouration of hair
Dyspepsia
Ehlers-Danlos like syndrome (in children)
Encephalopathy
Epidermal fragility
Gastro-enteritis
Gastro-intestinal ulceration
Genu valgum
Hallucinations
Headache
Joint hyperextension
Leg pain
Lethargy
Leucopenia
Nausea
Nephrotic syndrome
Nervousness
Osteopenia
Papilloedema
Pyrexia
Rash
Scoliosis progression
Skin odour changes
Somnolence
Striae
Unpleasant breath
Vertebral compression fractures
Vomiting

Overdosage

It is strongly recommended that the UK National Poisons Information Service be consulted on cases of suspected or actual overdose where there is doubt over the degree of risk or about appropriate management.

The following number will direct the caller to the relevant local centre (0844) 892 0111

Information may be obtained if you have access to ToxBase the primary clinical toxicology database of the National Poisons Information Service. This is available via password on the internet ( www.toxbase.org ) or if this is unavailable at the backup site ( www.toxbasebackup.org ).

Further Information

Last Full Review Date: June 2017

Reference Sources

Summary of Product Characteristics: Cystagon 50 mg hard capsules. Orphan Europe (UK) Limited. Revised February 2017.

Summary of Product Characteristics: Cystagon 150 mg hard capsules. Orphan Europe (UK) Limited. Revised February 2017.

Summary of Product Characteristics: Procysbi 25mg gastro-resistant capsules. Horizon Pharma Europe B.V. Revised December 2016.

Summary of Product Characteristics: Procysbi 75mg gastro-resistant capsules. Horizon Pharma Europe B.V. Revised December 2016.

NICE Evidence Services Available at: www.nice.org.uk Last accessed: 26 April 2022.