Cystagon Drug Information
Generic name: CYSTEAMINE BITARTRATE
Uses of Cystagon
® is indicated for the management of nephropathic cystinosis in children and adults.
Dosage & Administration of Cystagon
| 0 - 10 | 100 |
|---|---|
| 11 - 20 | 150 |
| 21 - 30 | 200 |
| 31 - 40 | 250 |
| 41 - 50 | 300 |
| 51 - 70 | 350 |
| 71 - 90 | 400 |
| 91 - 110 | 450 |
| > 110 | 500 |
Side Effects of Cystagon
In three clinical trials, cysteamine or phosphocysteamine have been administered to 246 children with cystinosis. Causality of side effects is sometimes difficult to determine because adverse effects may result from the underlying disease. The most frequent adverse reactions seen involve the gastrointestinal and central nervous systems.
These are especially prominent at the initiation of cysteamine therapy. Temporarily suspending treatment, then gradual re-introduction may be effective in improving tolerance. Adverse reactions were not collected systematically in the NCCS, but were often listed by investigators.
The following rates may therefore be underestimated. The most common events (> 5%) were vomiting 35%, anorexia 31%, fever 22%, diarrhea 16%, lethargy 11%, and rash 7%. Less common adverse events are: Body as a whole: Dehydration. Cardiovascular: Hypertension.
Digestive: Nausea, bad breath, abdominal pain, dyspepsia, constipation, gastroenteritis, duodenitis, gastrointestinal ulceration and bleeding. Central Nervous System: Somnolence, encephalopathy, headache, seizures, ataxia, confusion, tremor, hyperkinesia, decreasing hearing, dizziness, jitteriness. Psychiatric: Nervousness, abnormal thinking, depression, emotional lability, hallucinations, nightmares.
Integumentary: Urticaria. Urogenital: Interstitial nephritis, renal failure (see WARNINGS ). Clinical Laboratory: Abnormal liver function, anemia, leukopenia. Adverse reactions or intolerance leading to cessation of treatment occurred in 8% of patients in the U.S. Studies.
Withdrawals due to intolerance, vomiting associated with medication, anorexia, lethargy, and fever appeared dose related, occurring more frequently in those patients receiving 1.95 grams/m 2 /day as compared to 1.30 grams/m 2 /day. Dose in Grams/m 2 /day 1.30 ( n = 42 ) % 1.95 ( n = 51 ) % Vomiting Considered Related to Medicine 31 67 Anorexia 33 51 Lethargy 17 27 Diarrhea 31 31 Fever 28 45 Sudden deaths have been reported in this disease state. Post-marketing surveillance 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 (see PRECAUTIONS ).
Warnings & Cautions for Cystagon
If a skin rash develops, CYSTAGON ® should be withheld until the rash clears. CYSTAGON ® may be restarted at a lower dose under close supervision, then slowly titrated to the therapeutic dose. If a severe skin rash develops such as erythema multiforme bullosa or toxic epidermal necrolysis, CYSTAGON ® should not be readministered.
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. Neurological complications have been described in some cystinotic patients not on cysteamine treatment.
This may be a manifestation of the primary disorder. Patients should not engage in hazardous activities until the effects of CYSTAGON ® on mental performance are known. Gastrointestinal ulceration and bleeding have been reported in patients receiving 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 G.I. toxicity and what steps to take if they occur. Post-marketing reports include one report of interstitial nephritis with early renal failure. A causal relationship between this event and cysteamine bitartrate therapy has not been established.
Drug Interactions with Cystagon
Drug Interactions None have been described. CYSTAGON ® can be administered with electrolyte and mineral replacements necessary for management of the Fanconi Syndrome as well as vitamin D and thyroid hormone.
Pregnancy Safety for Cystagon
Pregnancy Teratology studies have been performed in rats at oral doses in a range of 37.5 to 150 mg/kg/day (about 0.2 to 0.7 times the recommended human maintenance dose on a body surface basis) and have revealed cysteamine bitartrate to be teratogenic and fetotoxic. Observed teratogenic findings were cleft palate, Kyphosis, heart ventricular septal defects, microcephaly and exencephaly. There are no adequate and well-controlled studies in pregnant women.
CYSTAGON ® should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Pediatric Use of Cystagon
Pediatric Use The safety and effectiveness of CYSTAGON ® for cystinotic children have been established. Cysteamine therapy should be initiated as soon as the diagnosis of nephropathic cystinosis has been confirmed.
Contraindications for Cystagon
® is contraindicated in patients who have developed hypersensitivity to it or to cysteamine or penicillamine.
Overdosage Information for Cystagon
A single oral dose of cysteamine at 660 mg/kg was lethal to rats. Symptoms of acute toxicity were reduction of motor activity and generalized hemorrhage in gastrointestinal tract and kidneys. Two cases of human overdosage have been reported.
In one case, the patient immediately vomited the drug and did not develop any symptoms. The second incident involved an accidental ingestion of a 200 to 250 mg/kg dose by a healthy 13 month old child. Vomiting and dehydration were experienced.
The child was hospitalized and fluids were administered. A full recovery was made. Should overdose occur, the respiratory and cardiovascular systems should be supported appropriately.
No specific antidote is known. Hemodialysis may be considered since cysteamine is poorly bound to plasma proteins.
Clinical Studies of Cystagon
Good Depletion Median leukocyte cystine levels were less than 1 nmol/½ cystine/mg
protein and received cysteamine for at least 1 year. (n = 19) 3.3 ± 2.2 7.2 ± 0.7 44.3 ± 15.0 50.5 ±
The Long Term Study, initiated in 1988, utilized both cysteamine HCl and
phosphocysteamine (patient’s choice) in 46 patients who had completed the NCCS (averaging 6.5 years of treatment) and 93 new patients. Patients had cystinosis diagnosed by elevated white cell cystine (mean 3.63 nmol/½ cystine/mg). New patients and 46 continuing patients were required to have serum creatinine less than 3.0 mg/dL and 4.0 mg/dL, respectively. Patients were randomized to doses of 1.3 or 1.95 g/m 2 /day and stratified according to whether the serum creatinine was above 1.2 mg/dL or not.
Doses could be raised if white cell cystine levels were approximately 2 nmol/½ cystine/mg protein and lowered due to intolerance. Mean doses were 1.27 g/m 2 /day and 1.87 g/m 2 /day in the two groups and white cell cystine levels averaged 1.72 ± 1.65 nmol/½ cystine/mg protein and 1.86 ± 0.92 nmol/½ cystine/mg protein in the 1.3 and 1.95 g/m 2 /day groups, respectively. In new patients, a group similar in age to the NCCS group, serum creatinine was essentially unchanged over the period of follow-up (about half of the patients were followed for 24 months) and phosphocysteamine and cysteamine HCl had similar effects.
The long-term follow-up group, about nine years old on average at entry, stayed in the study (almost 80% were followed at least 2 years) and had essentially no change in renal function. In four studies of untreated cystinosis, renal death (need for transplant or dialysis) occurred at median age of less than 10 years. Both groups maintained height (although they did not catch up from baseline). There was no apparent difference between the two doses.
Drug information sourced from the FDA. This content is for informational purposes only and does not constitute medical advice. Consult a healthcare professional before making any medication decisions.
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