Nephropathic cystinosis (specialist use only)
▶BY MOUTH
▶Adult (body-weight 50 kg and above): Initially one-sixth
to one-quarter of the expected maintenance dose,
increased gradually over 4–6 weeks to avoid
intolerance, maintenance 2 g daily in 4 divided doses
Corneal cystine crystal deposits in patients with cystinosis
(specialist use only)
▶TO THE EYE
▶Adult: Apply 1 drop 4 times a day, to be applied to both
eyes (minimum 4 hours between doses); dose may be
reduced according to response (minimum daily dose
1 drop in each eye)
DOSE EQUIVALENCE AND CONVERSION
▶With oral use
▶1.3 g/m2 is approximately equivalent to 50 mg/kg.
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▶When used by eye Contact lens wearers
▶With oral use Dose of phosphate supplement may need to
be adjusted if transferring from phosphocysteamine to
mercaptamine
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Contra-indicated if
history of hypersensitivity to penicillamine.
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Mercaptamine has a very unpleasant taste and smell,
which can affect compliance.
l HANDLING AND STORAGE
▶When used by eye Manufacturer advises store in a
refrigerator (2–8°C)—after opening store at room
temperature up to 25°C for up to 7 days; protect from light.
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Scottish Medicines Consortium (SMC) decisions
▶With oral use The Scottish Medicines Consortium has advised
(November 2017) that mercaptamine (Procysbi ®) is not
recommended for use within NHS Scotland for the
treatment of proven nephropathic cystinosis.
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