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Trade names | Cystagon, Procysbi, Cystaran, others |
Other names | 2-Aminoethanethiol, β-Mercaptoethylamine, 2-Mercaptoethylamine, decarboxycysteine, thioethanolamine, mercaptamine bitartrate, cysteamine (USAN US) |
AHFS/Drugs.com | Micromedex Detailed Consumer Information |
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Routes of administration | By mouth, eye drops |
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ECHA InfoCard | 100.000.421 |
Chemical and physical data | |
Formula | C2H7NS |
Molar mass | 77.15 g·mol−1 |
3D model (JSmol) | |
Melting point | 95 to 97 °C (203 to 207 °F) |
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Cysteamine is an organosulfur compound with the formula HSCH2CH2NH2. A white, water-soluble solid, it contains both an amine and a thiol functional groups. It is often used as salts of the ammonium derivative [HSCH2CH2NH3]+ [11] including the hydrochloride, phosphocysteamine, and the bitartrate. [12] The intermediate pantetheine is broken down into cysteamine and pantothenic acid. [12]
It is biosynthesized in mammals, including humans, by the degradation of coenzyme A. It is the biosynthetic precursor to the neurotransmitter hypotaurine. [13] [12]
As a medication, cysteamine, sold under the brand name Cystagon among others, is indicated to treat cystinosis, a lysosomal storage disease characterized by the abnormal accumulation of cystine, the oxidized dimer of the amino acid cysteine. [14] [5] [6] [7] It removes the excessive cystine that builds up in cells of people with the disease. [12] It is available by mouth (capsule and extended release capsule) and in eye drops. [15] [7] [8] [5] [9] [6] [10] [16]
When applied topically it can lighten skin that's been darkened as a result of post-inflammatory hyperpigmentation, sun exposure and Melasma. [17] [18] [19] [20] Tentative evidence suggests that it may be a more effective depigmentation agent than hydroquinone, retinoids and topical corticosteroids in individuals with chronic skin discoloration. [21] [22] [23] Topical application of cysteamine cream has also demonstrated similar efficacy to intradermal tranexamic acid injections for the treatment of Melasma but with much fewer adverse effects. [24]
The most important adverse effect related to topical use might be skin irritation.[ medical citation needed ] However it's significantly better tolerated than alternative skin lightening treatments with similar efficacy. [23] [24]
The label for oral formulations of cysteamine carry warnings about symptoms similar to Ehlers-Danlos syndrome, severe skin rashes, ulcers or bleeding in the stomach and intestines, central nervous symptoms including seizures, lethargy, somnolence, depression, and encephalopathy, low white blood cell levels, elevated alkaline phosphatase, and idiopathic intracranial hypertension that can cause headache, tinnitus, dizziness, nausea, double or blurry vision, loss of vision, and pain behind the eye or pain with eye movement. [7]
Additional adverse effects of oral cysteamine include bad breath, skin odor, vomiting, nausea, stomach pain, diarrhea, and loss of appetite. [7]
The drug is in pregnancy category C; the risks of cysteamine to a fetus are not known but it harms babies in animal models at doses less than those given to people. [5] [6]
For eye drops, the most common adverse effects are sensitivity to light, redness, and eye pain, headache, and visual field defects. [6]
There are no drug interactions for normal capsules or eye drops, [5] [6] but the extended release capsules should not be taken with drugs that affect stomach acid like proton pump inhibitors or with alcohol, as they can cause the drug to be released too quickly. [7] It doesn't inhibit any cytochrome P450 enzymes. [7]
People with cystinosis lack a functioning transporter (cystinosin) which transports cystine from the lysosome to the cytosol. This ultimately leads to buildup of cystine in lysosomes, where it crystallizes and damages cells. [15] Cysteamine enters lysosomes and converts cystine into cysteine and cysteine-cysteamine mixed disulfide, both of which can exit the lysosome. [7]
Cysteamine also promotes the transport of L-cysteine into cells. [12]
It is approved by the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA). [15] [7] [8] [9] [10] [25] [26]
In 2013, the regular capsule of cysteamine cost about $8,000 per year; the extended release form that was introduced that year was priced at $250,000 per year. [27]
The therapeutic effect of cysteamine on cystinosis was reported in the 1950s. Cysteamine was approved as a drug for cystinosis in the US in 1994. [7] An extended release form was approved in 2013. [27]
It was studied in in vitro and animal models for radiation protection in the 1950s, and in similar models from the 1970s onwards for sickle cell anemia, effects on growth, its ability to modulate the immune system, and as a possible inhibitor of HIV. [12]
In the 1970s it was tested in clinical trials for Paracetamol toxicity which it failed, and in clinical trials for systemic lupus erythematosus in the 1990s and early 2000s, which it also failed. [12]
Clinical trials in Huntington's disease were begun in the 1990s and were ongoing as of 2015. [12] [28]
As of 2013 [update] , it was in clinical trials for Parkinson's disease, malaria, radiation sickness, neurodegenerative disorders, neuropsychiatric disorders, and cancer treatment. [12] [ needs update ]
It has been studied in clinical trials for pediatric nonalcoholic fatty liver disease [29]
Acne, also known as acne vulgaris, is a long-term skin condition that occurs when dead skin cells and oil from the skin clog hair follicles. Typical features of the condition include blackheads or whiteheads, pimples, oily skin, and possible scarring. It primarily affects skin with a relatively high number of oil glands, including the face, upper part of the chest, and back. The resulting appearance can lead to lack of confidence, anxiety, reduced self-esteem, and, in extreme cases, depression or thoughts of suicide.
Cystine is the oxidized derivative of the amino acid cysteine and has the formula (SCH2CH(NH2)CO2H)2. It is a white solid that is poorly soluble in water. As a residue in proteins, cystine serves two functions: a site of redox reactions and a mechanical linkage that allows proteins to retain their three-dimensional structure.
Alopecia areata, also known as spot baldness, is a condition in which hair is lost from some or all areas of the body. It often results in a few bald spots on the scalp, each about the size of a coin. Psychological stress and illness are possible factors in bringing on alopecia areata in individuals at risk, but in most cases there is no obvious trigger. People are generally otherwise healthy. In a few cases, all the hair on the scalp is lost, or all body hair is lost. Hair loss can be permanent, or temporary.
Tretinoin, also known as all-trans retinoic acid (ATRA), is a medication used for the treatment of acne and acute promyelocytic leukemia. For acne, it is applied to the skin as a cream, gel or ointment. For leukemia, it is taken by mouth for up to three months. Topical tretinoin is also the most extensively investigated retinoid therapy for photoaging.
Rosacea is a long-term skin condition that typically affects the face. It results in redness, pimples, swelling, and small and superficial dilated blood vessels. Often, the nose, cheeks, forehead, and chin are most involved. A red, enlarged nose may occur in severe disease, a condition known as rhinophyma.
Pimecrolimus is an immunomodulating agent of the calcineurin inhibitor class used in the treatment of atopic dermatitis (eczema). It is available as a topical cream, once marketed by Novartis under the trade name Elidel.
Adapalene is a third-generation topical retinoid primarily used in the treatment of mild-moderate acne, and is also used off-label to treat keratosis pilaris as well as other skin conditions. Studies have found adapalene is as effective as other retinoids, while causing less irritation. It also has several advantages over other retinoids. The adapalene molecule is more stable compared to tretinoin and tazarotene, which leads to less concern for photodegradation. It is also chemically more stable compared to the other two retinoids, allowing it to be used in combination with benzoyl peroxide. Due to its effects on keratinocyte proliferation and differentiation, adapalene is superior to tretinoin for the treatment of comedonal acne and is often used as a first-line agent. The Swiss company Galderma sells adapalene under the brand-name product Differin.
Antipruritics, abirritants, or anti-itch drugs, are medications that inhibit the itching often associated with sunburns, allergic reactions, eczema, psoriasis, chickenpox, fungal infections, insect bites and stings like those from mosquitoes, fleas, and mites, and contact dermatitis and urticaria caused by plants such as poison ivy or stinging nettle. It can also be caused by chronic kidney disease and related conditions.
Hyperpigmentation is the darkening of an area of skin or nails caused by increased melanin.
Ivermectin is an antiparasitic drug. After its discovery in 1975, its first uses were in veterinary medicine to prevent and treat heartworm and acariasis. Approved for human use in 1987, it is used to treat infestations including head lice, scabies, river blindness (onchocerciasis), strongyloidiasis, trichuriasis, ascariasis and lymphatic filariasis. It works through many mechanisms to kill the targeted parasites, and can be taken by mouth, or applied to the skin for external infestations. It belongs to the avermectin family of medications.
Melasma is a tan or dark skin discoloration. Melasma is thought to be caused by sun exposure, genetic predisposition, hormone changes, and skin irritation. Although it can affect anyone, it is particularly common in women, especially pregnant women and those who are taking oral or patch contraceptives or hormone replacement therapy medications.
Eflornithine, sold under the brand name Vaniqa among others, is a medication used to treat African trypanosomiasis and excessive hair growth on the face in women. Specifically it is used for the second stage of sleeping sickness caused by T. b. gambiense and may be used with nifurtimox. It is taken intravenously or topically. It is an ornithine decarboxylase inhibitor.
Hydroquinone, also known as benzene-1,4-diol or quinol, is an aromatic organic compound that is a type of phenol, a derivative of benzene, having the chemical formula C6H4(OH)2. It has two hydroxyl groups bonded to a benzene ring in a para position. It is a white granular solid. Substituted derivatives of this parent compound are also referred to as hydroquinones. The name "hydroquinone" was coined by Friedrich Wöhler in 1843.
Cystinosis is a lysosomal storage disease characterized by the abnormal accumulation of cystine, the oxidized dimer of the amino acid cysteine. It is a genetic disorder that follows an autosomal recessive inheritance pattern. It is a rare autosomal recessive disorder resulting from accumulation of free cystine in lysosomes, eventually leading to intracellular crystal formation throughout the body. Cystinosis is the most common cause of Fanconi syndrome in the pediatric age group. Fanconi syndrome occurs when the function of cells in renal tubules is impaired, leading to abnormal amounts of carbohydrates and amino acids in the urine, excessive urination, and low blood levels of potassium and phosphates.
Azelaic acid (AzA) is an organic compound with the formula HOOC(CH2)7COOH. This saturated dicarboxylic acid exists as a white powder. It is found in wheat, rye, and barley. It is a precursor to diverse industrial products including polymers and plasticizers, as well as being a component of a number of hair and skin conditioners. AzA inhibits tyrosinase.
Imiquimod, sold under the brand name Aldara among others, is a medication that acts as an immune response modifier that is used to treat genital warts, superficial basal cell carcinoma, and actinic keratosis.
A lentigo is a small pigmented spot on the skin with a clearly defined edge, surrounded by normal-appearing skin. It is a harmless (benign) hyperplasia of melanocytes which is linear in its spread. This means the hyperplasia of melanocytes is restricted to the cell layer directly above the basement membrane of the epidermis where melanocytes normally reside. This is in contrast to the "nests" of multi-layer melanocytes found in moles. Because of this characteristic feature, the adjective "lentiginous" is used to describe other skin lesions that similarly proliferate linearly within the basal cell layer.
Liver spots are blemishes on the skin associated with aging and exposure to ultraviolet radiation from the sun. They range in color from light brown to red or black and are located in areas most often exposed to the sun, particularly the hands, face, shoulders, arms and forehead, and the scalp if bald.
CTNS may also refer to the Center for Theology and the Natural Sciences.
Nadifloxacin is a topical fluoroquinolone antibiotic for the treatment of acne vulgaris. It is also used to treat bacterial skin infections.