cysteamine (Rx)

Brand and Other Names:Cystagon, Procysbi
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

capsule, immediate-release (Cystagon)

  • 50mg
  • 150mg

capsule, delayed-release (Procysbi)

  • 25mg
  • 75mg

granules, delayed-release (Procysbi)

  • 75mg/packet
  • 300mg/packet

Nephropathic Cystinosis

Immediate-release capsule (Cystagon)

  • Starting dose: One-sixth to one-fourth of target maintenance dose
  • Maintenance: 2 g/day PO divided q6hr; dose should be reached after 4-6 weeks of incremental dosage increases; not to exceed 1.95 g/m²/day or 90 mg/kg/day  

Delayed-release capsule or granules (Procysbi)

  • Cysteamine-naïve patients
    • Starting dose: One-sixth to one-fourth of target maintenance dose
    • Gradually increase dose over 4-6 weeks until maintenance dosage is achieved to help reduce the risk of adverse reactions
    • Maintenance dose: 1.3 g/m2/day PO divided q12hr; may increase to 1.95 g/m2/day if WBC cystine level remains higher than the target, or cysteamine concentration has not been achieved  
    • If a patient experiences initial intolerance, temporarily discontinue and then restart at a lower dosage and gradually increase dosage
  • Dosage titration to therapeutic target WBC cystine concentration
    • Measure WBC cystine concentration and titrate dose as needed to achieve the therapeutic target WBC cysteine concentration
    • If a dose adjustment is required, increase dosage by 10%, rounded to nearest dosage that can be administered using available strengths of capsules or packets of oral granules
    • If adverse reactions occur, decrease dosage; some patients may be unable to achieve their therapeutic target due to poor tolerability
  • Switching from immediate-release capsules to Procysbi
    • Starting total daily dose of Procysbi should be equal to previous total daily dose of immediate-release cysteamine bitartrate
    • Measure WBC cystine concentration 2 weeks after initiation
    • Titrate dose as needed to achieve target WBC cystine concentrations
    • Do not exceed 1.95 g/m2/day

Dosage Modifications

Renal impairment

  • Increased exposure to cysteamine in patients with renal impairment compared to healthy subjects is not considered to be clinically meaningful

Dosing Considerations

Monitoring parameters

  • Recommended target WBC cystine concentration: <1 nmol ½ cystine/mg protein (using mixed leukocyte assay)
  • Cysteamine-naïve patients: Obtain WBC cystine concentration after reaching the maintenance Procysbi dose, then monthly for 3 months, quarterly for 1 year, and then twice-yearly, at a minimum
  • Switching from immediate-release cysteamine to Procysbi: Obtain WBC cystine concentration 2 weeks after initiating treatment and continue monitoring if further dosage titration is required to achieve therapeutic target WBC cystine concentration
  • Once the therapeutic target is achieved, continue monitoring quarterly for 6 months, then twice yearly, at a minimum
  • Obtain WBC cystine concentration 12 hr after the patient’s last dose, before administration of the next dose (ie, trough concentration)
  • It is important to accurately record the time of the last dose, the actual dose, and the time the blood sample was taken

Cystic Fibrosis (Orphan)

Lynovex: Orphan designation for cystic fibrosis

Sponsor

  • NovaBiotics Ltd.; Cruickshank Building, Craibstone; Aberdeen AB21 9TR; United Kingdom

Huntington Disease (Orphan)

Orphan indication sponsor

  • Bennu Pharmaceuticals, Inc (dual EMEA); 9 Commercial Blvd; Novato, CA 94949

Batten Disease (Orphan)

Treatment of neuronal ceroid lipofuscinoses (Batten disease)

Orphan indication sponsor

  • Bennu Pharmaceuticals, Inc. (dual EMEA); 9 Commercial Blvd; Novato, CA 94949

Pancreatic Cancer (Orphan)

Orphan designation for treatment of pancreatic cancer

Orphan sponsor

  • Raptor Pharmaceuticals, Inc.; 5 Hamilton Landing, Suite 160, Novato, CA 94949

Dosage Forms & Strengths

capsule, immediate-release (Cystagon)

  • 50mg
  • 150mg

capsule, delayed-release (Procysbi)

  • 25mg
  • 75mg

granules, delayed-release (Procysbi)

  • 75mg/packet
  • 300mg/packet

Nephropathic Cystinosis

Immediate-release capsule (Cystagon)

  • Initial: give one-sixth to one-fourth of maintenace dose
  • Maintenance (<12 years): 1.3 g/m²/day or 60 mg/kg/day of free base PO divided q6hr; not to exceed 1.95 g/m²/day or 90 mg/kg/day  
  • Maintenance (≥12 years or >110 lbs): 2 g/day PO divided q6hr; dose should be reached after 4-6 weeks of incremental dosage increases; not to exceed 1.95 g/m²/day or 90 mg/kg/day

Delayed-release capsule (Procysbi)

  • <1 years: Safety and efficacy not established
  • Initiate cysteamine treatment immediately after diagnosis of nephropathic cystinosis
  • Cysteamine-naïve patients
    • Initial dose is a fraction of the maintenance dose (ie, one-sixth to one-fourth of the maintenance dose)
    • Maintenance dose: 1.3 g/m²/day PO divided q12hr
    • 1-6 years: Increase dose in 10% increments to the maintenance dosage, while monitoring WBC cystine concentrations; allow a minimum of 2 weeks between dosage adjustments; if patient achieves the therapeutic target WBC cystine concentration at a dosage below the recommended weight-based maintenance dosage, then stop dosage escalation and use the dosage as the patient's maintenance dosage
    • ≥6 years: Gradually increase dose over 4-6 weeks until maintenance dose achieved
    • If a patient experiences initial intolerance, temporarily discontinue drug and then restart at a lower dosage and gradually increase dosage
    • After maintenance dosage achieved, the dose may need to be further increased to achieve a therapeutic target WBC cystine concentration; maximum dose is 1.95 g/m²/day
    • Round dose calculations to the nearest incremental dosage that can be administered using the available capsule strengths; only use whole capsules
  • Switching from immediate-release capsules to Procysbi
    • Starting total daily dose of Procysbi should be equal to previous total daily dose of immediate-release cysteamine bitartrate
    • Measure WBC cystine concentration 2 weeks after initiation
    • Titrate dose as needed to achieve target WBC cystine concentrations

Dosage Modifications

Renal impairment

  • Increased exposure to cysteamine in patients with renal impairment compared to healthy subjects is not considered to be clinically meaningful

Dosing Considerations

Monitoring parameters

  • Recommended target WBC cystine concentration: <1 nmol ½ cystine/mg protein (using mixed leukocyte assay)
  • Cysteamine-naïve patients: Obtain WBC cystine concentration after reaching the maintenance Procysbi dose, then monthly for 3 months, quarterly for 1 year, and then twice-yearly, at a minimum
  • Switching from immediate-release cysteamine to Procysbi: Obtain WBC cystine concentration 2 weeks after initiating treatment and continue monitoring if further dosage titration is required to achieve therapeutic target WBC cystine concentration
  • Once the therapeutic target is achieved, continue monitoring quarterly for 6 months, then twice yearly, at a minimum
  • Obtain WBC cystine concentration 12 hr after the patient’s last dose, before administration of the next dose (ie, trough concentration)
  • It is important to accurately record the time of the last dose, the actual dose, and the time the blood sample was taken

Fanconi Syndrome (Off-label)

Delayed-release capsule (Procysbi)

Used to reduce cystine levels, potentially delaying kidney and other damage

Initial: Use one-sixth to one-fourth the maintenance dose

Maintenance: 1.3 g/m2/day PO divided q12hr; may increase to 1.95 g/m2/day if WBC cystine level remains higher than the target, or cysteamine concentration has not been achieved

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Adverse Effects

>10%

Diarrhea

Nausea

Conjunctivus

Influenza

Gastroenteritis

Nasopharyngitis

Abdominal pain

Dehydration

Ear infection

Upper respiratory tract infection

Fatigue

Arthralgia

Cough

Pain in extremity

Immediate-release cysteamine

  • Vomiting/emesis (12%)

Delayed-release cysteamine

  • Vomiting/emesis (19-77%)
  • Gastroenteritis/viral gastroenteritis (53%)
  • Breath odor (24%)
  • Nausea (16-18%)
  • Abdominal pain/discomfort (14%)
  • Electrolyte imbalance (12%)
  • Headache (9-12%)

1-10%

Immediate-release cysteamine

  • Nausea (7%)
  • Anorexia/loss of appetite (5%)

Delayed-release cysteamine

  • Dizziness (5%)
  • Anorexia/loss of appetite (2%)

Postmarketing reports

Musculoskeletal: Joint hyperextension, leg pain, osteopenia, compression fracture, scoliosis, genu valgum

Skin: Erythema multiforme bullosa, toxic epidermal necrolysis, Ehlers-Danlos-like syndrome, molluscoid pseudotumors, skin striae, skin fragility

Central nervous system: seizures, lethargy, somnolence, depression and encephalopathy, benign intracranial hypertension (or PTC) and/or papilledema

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Warnings

Contraindications

Hypersensitivity to cysteamine or penicillamine

Cautions

Skin and bone lesions that resemble clinical findings for Ehlers-Danlos-like syndrome have been reported in patients treated with high doses of immediate-release cysteamine bitartrate or other cysteamine salts; these include molluscoid pseudotumors (purplish hemorrhagic lesions), skin striae, bone lesions (including osteopenia, compression fractures, scoliosis and genu valgum), leg pain, and joint hyperextension; monitor for development of skin or bone lesions and interrupt dosing if patients develop these lesions; restart at a lower dose under close supervision, then slowly increase to the appropriate therapeutic dose

Immediate-release cysteamine bitartrate

  • Severe skin rashes (eg, erythema multiforme bullosa, toxic epidermal necrolysis) have been reported; if severe skin rashes develop, permanently discontinue use
  • Gastrointestinal (GI) ulceration and bleeding have been reported; GI tract symptoms including nausea, vomiting, anorexia and abdominal pain, sometimes severe; if severe GI tract symptoms develop, consider decreasing the Procysbi dose
  • May cause CNS symptoms such as seizures, lethargy, somnolence, depression, and encephalopathy; interrupt medication or adjust the dose as necessary for patients with severe symptoms or with symptoms that persist or progress; may impair their ability to perform tasks such as driving or operating machinery
  • Cysteamine has been associated with reversible leukopenia and elevated alkaline phosphatase levels
  • Benign intracranial hypertension (pseudotumor cerebri; PTC) and/or papilledema have been reported; monitor for signs and symptoms of PTC, including headache, tinnitus, dizziness, nausea, diplopia, blurry vision, loss of vision, pain behind the eye or pain with eye movement; if signs/symptoms persist, interrupt or decrease dose and refer to an ophthalmologist; if diagnosis is confirmed, permanently discontinue use

Drug interaction overview

Drugs that increase the gastric pH (eg, medications containing bicarbonate or carbonate) may alter the pharmacokinetics of cysteamine due to the premature release of cysteamine and increase WBC cystine concentration; monitor WBC cystine concentration when drugs that increase the gastric pH are concomitantly used

Consumption of alcohol with cysteamine may increase the rate of cysteamine release and/or adversely alter the pharmacokinetic properties, as well as the effectiveness and toxicities; therefore, do not consume alcoholic beverages during treatment

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Pregnancy & Lactation

Pregnancy

There are no available data on use in pregnant women to inform any drug-associated risks for birth defects or miscarriage; use during pregnancy only if potential benefits justify potential risk to fetus

Cysteamine (administered as cysteamine bitartrate) was teratogenic and fetotoxic in rats at doses less than the recommended human maintenance dose

Lactation

There is no information on the presence of cysteamine in human milk, the effects on the breast-fed infant, or the effects on milk production

Cysteamine is present in the milk of lactating rats

Owing to the potential for serious adverse reactions in breastfed infants from cysteamine, breastfeeding is not recommended

Pregnancy Categories

A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

NA: Information not available.

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Pharmacology

Mechanism of Action

Converts lysosomal cystine to cysteine & to cysteine-cysteamine mixed disulfide which then can exit lysosome in patients with cystinosis (inherited defect of lysosomal transport)

Pharmacokinetics

Onset: 1-1.8 hr

Duration: 6-12 hr

Peak plasma time: 1.4 hr

Vd: 156 L

Bioavailability: Rapidly absorbed

Protein Bound: 52% (mainly albumin)

Excretion: Small amount excreted in urine

Dialyzable: PD: yes, HD: no data

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Administration

Oral Administration

Cystagon

  • May open capsules and sprinkle on food
  • Missed dose
    • If a dose is missed, take the dose as soon as possible; if it is within 2 hr of the next dose, skip the missed dose and go back to the regular dosing schedule
    • Do not double the dose

Procysbi delayed-release capsules or granules

  • Administer at least 1 hr before or after medications containing bicarbonate or carbonate
  • Do not eat for at least 2 hr before taking Procysbi and for at least 30 minutes after to maximize absorption
  • If patients are unable to take Procysbi without eating, take with food and limit the amount of food to ~4 ounces (1∕2 cup) within 1 hr before taking Procysbi through 1 hr after taking Procysbi
  • Take in a consistent manner in regard to food
  • Avoid high-fat food close to dosing
  • Unable to swallow capsule
    • If unable to swallow, may open capsule and sprinkle intact granules on ~4 oz applesauce or berry jelly; eat mixture within 30 minutes, OR
    • May disperse intact granules into small volume of either orange juice or apple juice (~4 oz), shake gently for 5 minutes, then administer by spoon or cup within 30 minutes
    • Do not chew the granules
    • ≥12 French G-tube: Mix intact granules with 4 oz applesauce and administer via feeding tube within 30 minutes; flush with ~8 oz or orange juice or apple juice to clear the tube
    • Use mixtures within 30 min; do not save the mixtures for later use
  • Missed dose
    • <8 hr after missed dose: Take dose as soon as possible
    • <4 hr until next scheduled dose: Do not take missed dose; take next dose at the usual scheduled time
    • Do not take 2 doses at the same time to make up for a missed dose

Storage

Immediate-release capsules

  • Store at room temperature, 20-25ºC (68-77ºF) in the original packaging

Delayed-release capsules and granules

  • Store at room temperature, 20-25ºC (68-77ºF) in the original packaging
  • Do not subdivide or repackage
  • Protect from light and moisture
  • Do not store delayed-release oral granules in opened packets
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Formulary

FormularyPatient Discounts

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The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

Tier Description
1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
NC NOT COVERED – Drugs that are not covered by the plan.
Code Definition
PA Prior Authorization
Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
QL Quantity Limits
Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
ST Step Therapy
Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
OR Other Restrictions
Drugs that have restrictions other than prior authorization, quantity limits, and step therapy associated with each prescription.
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Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.