An overdose of cysteamine may cause progressive lethargy.
Should overdosing occur, the respiratory and cardiovascular systems should be supported appropriately. No specific antidote is known. It is not known if cysteamine is removed by haemodialysis.
-
- Hypersensitivity to penicillamine.
- Breast-feeding.
Not applicable.
Summary of the safety profile
For the immediate-release formulation of cysteamine bitartrate, approximately 35% of patients can be expected to experience adverse reactions. These mainly involve the gastrointestinal and central nervous systems. When these reactions appear at the initiation of cysteamine therapy, temporary suspension and gradual reintroduction of treatment may be effective in improving tolerance.
In clinical studies with healthy volunteers, the most frequent adverse reactions were very common GI symptoms (16%) and occurred primarily as single episodes that were mild or moderate in severity. The AE profile for healthy subjects was similar to the AE profile in patients relative to GI disorders (diarrhoea and abdominal pain).
Tabulated list of adverse reactions
Reported adverse reactions are listed below, by system organ class and by frequency. Frequencies are defined as: very common (> 1/10), common (> 1/100 to < 1/10) and uncommon (> 1/1,000 to < 1/100). Within each frequency grouping, adverse reactions are presented in order of decreasing seriousness:
| Blood and lymphatic system disorders | Uncommon: Leukopenia |
| Immune system disorders | Uncommon: Anaphylactic reaction |
| Metabolism and nutrition disorders | Very common: Anorexia |
| Psychiatric disorders | Uncommon: Nervousness, hallucination |
| Nervous system disorders | Common: Headache, encephalopathy |
| Uncommon: Somnolence, convulsions | |
| Gastrointestinal disorders | Very common: Vomiting, nausea, diarrhoea |
| Common: Abdominal pain, breath odour, dyspepsia, gastroenteritis | |
| Uncommon: Gastrointestinal ulcer | |
| Skin and subcutaneous tissue disorders | Common: Skin odour abnormal, rash |
| Uncommon: Hair colour changes, skin striae, skin fragility (molluscoid pseudotumour on elbows) | |
| Musculoskeletal and connective tissue disorders | Uncommon: Joint hyperextension, leg pain, genu valgum, osteopenia, compression fracture, scoliosis. |
| Renal and urinary disorders | Uncommon: Nephrotic syndrome |
| General disorders and administration site conditions | Very common: Lethargy, pyrexia |
| Common: Asthenia | |
| Investigations | Common: Liver function tests abnormal |
Description of selected adverse reactions
Clinical studies experience with Cystadrops
In clinical studies comparing Cystadrops to the immediate-release cysteamine bitartrate, one third of the patients exhibited very common GI disorders (nausea, vomiting, abdominal pain). Common nervous system disorders (headache, somnolence and lethargy) and common general disorders (asthenia) were also seen.
Post-marketing experience with immediate-release cysteamine bitartrate
Benign intracranial hypertension (or pseudotumor cerebri (PTC)) with papilledema; skin lesions, molluscoid pseudotumors, skin striae, skin fragility; joint hyperextension, leg pain, genu valgum, osteopenia, compression fracture and scoliosis have been reported with immediate-release cysteamine bitartrate.
Two cases of nephrotic syndrome have been reported within 6 months of starting therapy with progressive recovery after treatment discontinuation. Histology showed a membranous glomerulonephritis of the renal allograft in one case and hypersensitivity interstitial nephritis in the other.
A few cases of Ehlers-Danlos-like syndrome on elbows have been reported in children chronically treated with high doses of different cysteamine preparations (cysteamine chlorhydrate or cystamine or cysteamine bitartrate) mostly above the maximal dose 1.95 g/m2/day. In some cases, these skin lesions were associated with skin striae and bone lesions first seen during an X-ray examination. Bone disorders reported were genu valgum, leg pain and hyperextensive joints, osteopenia, compression fractures, and scoliosis. In the few cases where histopathological examination of the skin was performed, the results suggested angioendotheliomatosis. One patient subsequently died of acute cerebral ischemia with marked vasculopathy. In some patients, the skin lesions on elbows regressed after immediate-release cysteamine dose reduction.
Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme in the UK at www.mhra.gov.uk/yellowcard. Or in Ireland to HPRA Pharmacovigilance, Earlsfort Terrace, IRL - Dublin 2; Tel: +353 1 6764971; Fax: +353 1 6762517. Website: www.hpra.ie; E-mail: [email protected].
Genotoxicity studies have been published using cysteamine, induction of chromosome aberrations in cultured eukaryotic cell lines has been reported, specific studies with cysteamine did not show any mutagenic effects in the Ames test or any clastogenic effect in the mouse micronucleus test. A bacterial reverse mutation assay study (“Ames testâ€) was performed with the cysteamine bitartrate used for Cystadrops and cysteamine bitartrate did not show any mutagenic effects in this test.
Reproduction studies showed embryo-foetotoxic effects (resorptions and post-implantation losses) in rats at the 100 mg/kg/day dose level and in rabbits receiving cysteamine 50 mg/kg/day. Teratogenic effects have been described in rats when cysteamine is administered over the period of organogenesis at a dose of 100 mg/kg/day.
This is equivalent to 0.6 g/m2/day in the rat, which is slightly less than the recommended clinical maintenance dose of cysteamine, i.e. 1.3 g/m2/day. A reduction of fertility was observed in rats at 375 mg/kg/day, a dose at which body weight gain was retarded. At this dose, weight gain and survival of the offspring during lactation was also reduced. High doses of cysteamine impair the ability of lactating mothers to feed their pups. Single doses of the drug inhibit prolactin secretion in animals.
Administration of cysteamine in neonate rats induced cataracts.
High doses of cysteamine, either by oral or parenteral routes, produce duodenal ulcers in rats and mice but not in monkeys. Experimental administration of the drug causes depletion of somatostatin in several animal species. The consequence of this for the clinical use of the drug is unknown.
No carcinogenic studies have been conducted with cysteamine bitartrarte gastro-resistant hard capsules.
Cystadrops is indicated for the treatment of proven nephropathic cystinosis. Cysteamine reduces cystine accumulation in some cells (e.g. leukocytes, muscle and liver cells) of nephropathic cystinosis patients and, when treatment is started early, it delays the development of renal failure.
Pharmacotherapeutic group: Other alimentary tract and metabolism product, ATC code: A16AA04.
Cysteamine is the simplest stable aminothiol and a degradation product of the amino acid cysteine. Cysteamine participates within lysosomes in a thiol-disulfide interchange reaction converting cystine into cysteine and cysteine-cysteamine mixed disulfide, both of which can exit the lysosome in patients with cystinosis.
Normal individuals and persons heterozygous for cystinosis have white blood cell cystine levels of < 0.2 and usually below 1 nmol hemicystine/mg protein, respectively. Individuals with cystinosis have elevations of WBC cystine above 2 nmol hemicystine/mg protein.
WBC cystine is monitored in these patients to determine adequacy of dosing, levels being measured 30 minutes after dosing when treated with Cystadrops.
A pivotal phase 3 randomized, crossover PK and PD study (which was also the first ever randomized study with immediate-release cysteamine bitartrate) demonstrated that at steady-state, patients receiving Cystadrops every 12 hours (Q12H) maintained a comparable depletion of WBC cystine levels compared to immediate-release cysteamine bitartrate every 6 hours (Q6H). Forty-three 43) patients were randomized; twenty-seven (27) children (ages 6 to 12 years old), fifteen (15) adolescents (ages 12 to 21 years old) and one (1) adult with cystinosis and with native kidney function based on an estimated GFR (corrected for body surface area) > 30 mL/minute/1.73 m2 were randomized. Of those forty-three (43) patients, two(2) siblings withdrew at the end of the first crossover period, due to a prior planned surgery in one (1) of them; forty-one (41) patients completed the protocol. Two (2) patients were excluded from the per-protocol analysis because their WBC cystine level increased over 2 nmol hemicystine/mg protein during the immediate-release cysteamine treatment period. Thirty-nine (39) patients were included in the final primary per protocol efficacy analysis.
| Per -Protocol (PP) Population (N=39) | ||
| Immediate-release cysteamine bitartrate | Cystadrops | |
| WBC cystine level (LS Mean ± SE) in nmol hemicystine/mg protein | 0.44 ± 0.05 | 0.51 ± 0.05 |
| Treatment effect (LS mean ± SE; 95.8% CI; p-value) | 0.08 ± 0.03 ; 0.01 to 0.15; <0.0001 | |
| All Evaluable Patients (ITT) Population (N=41) | ||
| Immediate-release cysteamine bitartrate | Cystadrops | |
| WBC cystine level (LS Mean ± SE) in nmol hemicystine/mg protein | 0.74 ± 0.14 | 0.53 ± 0.14 |
| Treatment effect (LS mean ± SE; 95.8% CI; p-value) | -0.21 ± 0.14 ; -0.48 to 0.06; <0.001 | |
Forty of forty-one (40/41) patients who completed the pivotal phase 3 study were entered in a prospective study with Cystadrops that stayed open as long as Cystadrops could not be prescribed by their treating physician. In this study, the WBC cystine was always on average under optimal control at < 1 nmol hemicystine/mg protein. The estimated glomerular filtration rate (eGFR) did not change for the study population over time.
Absorption
The relative bioavailability is about 125% as compared to immediate-release cysteamine.
Food intake reduces the absorption of Cystadrops at 30 minutes pre-dose (approximately 35% decrease in exposure) and at 30 min post-dose (approximately 16 or 45% decrease in exposure for intact and open capsules respectively). Food intake two hours after administration did not affect the absorption of Cystadrops.
Distribution
The in vitro plasma protein binding of cysteamine, primarily to albumin, is approximately 54% and independent of plasma drug concentration over the therapeutic range.
Biotransformation
The elimination of unchanged cysteamine in the urine has been shown to range between 0.3 % and 1.7% of the total daily dose in four patients; the bulk of cysteamine is excreted as sulphate.
In vitro data suggests that cysteamine bitartrate is likely to be metabolized by multiple CYP enzymes, including CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP2E1. CYP2A6 and CYP3A4 were not involved in the metabolism of cysteamine bitartrate under the experimental conditions.
Elimination
The terminal half-life of cysteamine bitartrate is approximately 4 hours.
Cysteamine bitartrate is not an inhibitor of CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4 in vitro.
In vitro: Cysteamine bitartrate is a substrate of P-gp and OCT2, but not a substrate of BCRP, OATP1B1, OATP1B3, OAT1, OAT3 and OCT1. Cysteamine bitartrate is not an inhibitor of OAT1, OAT3 and OCT2.
Special populations
The pharmacokinetics of cysteamine bitartrate has not been studied in special populations.
Cysteamine therapy must be initiated promptly once the diagnosis is confirmed (i.e., increased WBC cystine) to achieve maximum benefit.
The use of doses higher than 1.9 g/m2/day is not recommended.
Oral cysteamine has not been shown to prevent eye deposition of cystine crystals. Therefore, where cysteamine ophthalmic solution is used for that purpose, its usage should continue.
If a pregnancy is diagnosed or planned, the treatment should be carefully reconsidered and the patient must be advised of the possible teratogenic risk of cysteamine.
Intact capsules of Cystadrops should not be administered to children under the age of approximately 6 years due to risk of aspiration.
Dermatological
There have been reports of serious skin lesions in patients treated with high doses of immediate-release cysteamine bitartrate or other cysteamine salts that have responded to cysteamine dose reduction. Physicians should routinely monitor the skin and bones of patients receiving cysteamine.
If skin or bone abnormalities appear, the dose of cysteamine should be reduced or stopped. Treatment may be restarted at a lower dose under close supervision, and then slowly titrated to the appropriate therapeutic dose. If a severe skin rash develops such as erythema multiforme bullosa or toxic epidermal necrolysis, cysteamine should not be re-administered.
Gastrointestinal
GI ulceration and bleeding have been reported in patients receiving immediate-release cysteamine bitartrate. Physicians should remain alert for signs of ulceration and bleeding and should inform patients and/or guardians about the signs and symptoms of serious GI toxicity and what steps to take if they occur.
GI tract symptoms including nausea, vomiting, anorexia and abdominal pain have been associated with cysteamine.
Strictures of the ileo-caecum and large bowel (fibrosing colonopathy) was first described in cystic fibrosis patients who were given high doses of pancreatic enzymes in the form of tablets with an enteric coating of methacrylic acid- ethyl acrylate copolymer, one of the excipients in Cystadrops. As a precaution, unusual abdominal symptoms or changes in abdominal symptoms should be medically assessed to exclude the possibility of fibrosing colonopathy.
Central Nervous System (CNS)
CNS symptoms such as seizures, lethargy, somnolence, depression, and encephalopathy have been associated with cysteamine. If CNS symptoms develop, the patient should be carefully evaluated and the dose adjusted as necessary. Patients should not engage in potentially hazardous activities until the effects of cysteamine on mental performance are known.
Leukopenia and abnormal liver function
Cysteamine has occasionally been associated with reversible leukopenia and abnormal liver function studies. Therefore, blood counts and liver function should be monitored.
Benign intracranial hypertension
There have been reports of benign intracranial hypertension (or pseudotumor cerebri (PTC)) and/or papilledema associated with cysteamine bitartrate treatment that has resolved with the addition of diuretic therapy (post-marketing experience with the immediate-release cysteamine bitartrate). Physicians should instruct patients to report any of the following symptoms: headache, tinnitus, dizziness, nausea, diplopia, blurred vision, loss of vision, pain behind the eye or pain with eye movement. A periodic eye examination is needed to identify this condition early and timely treatment should be provided when it occurs to prevent vision loss.
Important information about some of the ingredients of Cystadrops
This medicinal product contains less than 1 mmol sodium (23 mg) per dose, i.e. essentially sodium-free.
Cysteamine has minor or moderate influence on the ability to drive and use machines.
Cysteamine may cause drowsiness. When starting therapy, patients should not engage in potentially hazardous activities until the effects of the medicinal product on each individual are known.
Cystadrops treatment should be initiated under the supervision of a physician experienced in the treatment of cystinosis.
Posology
The assay-dependent therapeutic goal is to maintain a white blood cell (WBC) cystine level < 1 nmol hemicystine/mg protein, 30 min after dosing, by adjusting the dose. For patients adherent to a stable dose of Cystadrops, and who do not have easy access to an adequate facility for measuring their WBC cystine, the goal of therapy should be to maintain plasma cysteamine concentration > 0.1 mg/L, 30 min after dosing.
Transferring patients from immediate-release cysteamine bitartrate hard capsules
Patients with cystinosis taking immediate-release cysteamine bitartrate may be transferred to a total daily dose of Cystadrops equal to their previous total daily dose of immediate-release cysteamine bitartrate. Patients being transferred from immediate-release cysteamine bitartrate to Cystadrops should have their WBC cystine levels measured in 2 weeks, and thereafter every 3 months to assess optimal dosage as described above.
Measurement timing: The determination of WBC cystine and/or plasma cysteamine must be obtained 12.5 hours after the evening dose the day before, and therefore 30 minutes after the following morning dose is given.
Newly diagnosed adult patients
Newly diagnosed adult patients should be started on 1/6 to 1/4 of the targeted maintenance dose of Cystadrops. The targeted maintenance dose is 1.3 gram/m2/day, in two divided doses, given every 12 hours. The dose should be raised if there is adequate tolerance and the WBC cystine level remains > 1 nmol hemicystine/mg protein. The maximum recommended dose of cysteamine is 1.95 g/m2/day. The use of doses higher than 1.95 g/m2/day is not recommended.
Newly diagnosed paediatric population
The targeted maintenance dose of 1.3 g/m2/day can be approximated according to the following table, which takes surface area as well as weight into consideration.
| Weight in kilograms | Recommended dose in mg Every 12 hours |
| 0-5 | 200 |
| 5-10 | 300 |
| 11-15 | 400 |
| 16-20 | 500 |
| 21-25 | 600 |
| 26-30 | 700 |
| 31-40 | 800 |
| 41-50 | 900 |
| > 50 | 1000 |
Special populations
Patients with poor tolerability
Patients with poorer tolerability still receive significant benefit if white blood cell cystine levels are below 2 nmol hemicystine/mg protein. The cysteamine dose can be increased to a maximum of 1.95 grams/m2/day to achieve this level. The dose of 1.95 grams/m2/day of immediate-release cysteamine bitartrate has been associated with an increased rate of withdrawal from treatment due to intolerance and an increased incidence of adverse events. If cysteamine is initially poorly tolerated due to gastrointestinal (GI) tract symptoms or transient skin rashes, therapy should be temporarily stopped, then re-instituted at a lower dose and gradually increased to the appropriate dose.
Patients on dialysis or post-transplantation
Experience has occasionally shown that some forms of cysteamine are less well tolerated (i.e. leading to more adverse events) when patients are on dialysis. A closer monitoring of the WBC cystine levels is recommended in these patients.
Patients with renal impairment
Dose adjustment is not normally required; however, WBC cystine levels should be monitored.
Patients with hepatic impairment
Dose adjustment is not normally required; however, WBC cystine levels should be monitored.
Method of administration
Oral use. Cysteamine bitartrate should not be administered with food rich in fat or proteins, or with frozen food like ice-cream.
Missed doses
If a dose is missed, it should be taken as soon as possible. If it is within four hours of the next dose, skip the missed dose and go back to the regular dosing schedule. Do not double the dose.
Administration with food
Patients should try to consistently avoid meals and dairy products for at least 1 hour before and 1 hour after Cystadrops dosing. If fasting during this period is not possible, it is acceptable to eat only a small amount ( 100 grams) of food (preferentially carbohydrates) during the hour before and after Cystadrops administration. It is important to dose Cystadrops in relation to food intake in a consistent and reproducible way over time
In paediatric patients who are at risk of aspiration, aged approximately 6 years and under, the hard capsules should be opened and the content sprinkled on food or liquid listed below.
Sprinkling on food
Capsules for either the morning or evening dose should be opened and the contents sprinkled onto approximately 100 grams of apple compote or berry jelly. Gently stir the contents into the soft food, creating a mixture of cysteamine granules and food. The entire amount of the mixture should be eaten. This may be followed by 250 mL of an acceptable acidic liquid - fruit juice (e.g., orange juice or any acidic fruit juice). The mixture must be eaten within 2 hours after preparation and must be refrigerated from the time of preparation to the time of administration.
Administering through feeding tubes
Capsules for either the morning or evening dose should be opened and the contents sprinkled onto approximately 100 grams of apple compote or berry jelly. Gently stir the contents into the soft food, creating a mixture of cysteamine granules and the soft food. The mixture should then be administered via gastrostomy tube, nasogastric tube or gastrostomy-jejunostomy tube. The mixture must be administered within 2 hours after preparation and may be refrigerated from the time of preparation to the time of administration.
Sprinkling in orange juice or any acidic fruit juice
Capsules for either the morning or evening dose should be opened and the contents sprinkled into 100 to 150 mL of acidic fruit juice. Dose administration options are provided below:
- Option 1 / Syringe: Mix gently for 5 minutes, then aspirate the mixture of cysteamine granules and acidic fruit juice into a dosing syringe.
- Option 2 / Cup: Mix gently for 5 minutes in a cup or shake gently for 5 minutes in a covered cup (e.g., “sippy†cup). Drink the mixture of cysteamine granules and acidic fruit juice.
The mixture must be administered (drunk) within 30 minutes after preparation and must be refrigerated from the time of preparation to the time of administration.
No special requirements.
