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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]+ [12] including the hydrochloride, phosphocysteamine, and the bitartrate. [13] The intermediate pantetheine is broken down into cysteamine and pantothenic acid. [13]
It is biosynthesized in mammals, including humans, by the degradation of coenzyme A. It is the biosynthetic precursor to the neurotransmitter hypotaurine. [14] [13]
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. [15] [6] [7] [8] It removes the excessive cystine that builds up in cells of people with the disease. [13] It is available by mouth (capsule and extended release capsule) and in eye drops. [16] [8] [9] [6] [10] [7] [11] [17]
When applied topically it can lighten skin that's been darkened as a result of post-inflammatory hyperpigmentation, sun exposure and melasma. [18] [19] [20] [21] Tentative evidence suggests that it may be a more effective depigmentation agent than hydroquinone, retinoids and topical corticosteroids in individuals with chronic skin discoloration. [22] [23] [24] 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. [25]
Cysteamine is better tolerated than alternative skin lightening treatments with similar efficacy. [24] [25]
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. [8]
Additional adverse effects of oral cysteamine include bad breath, skin odor, vomiting, nausea, stomach pain, diarrhea, and loss of appetite. [8]
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. [6] [7]
For eye drops, the most common adverse effects are sensitivity to light, redness, and eye pain, headache, and visual field defects. [7]
There are no drug interactions for normal capsules or eye drops, [6] [7] 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. [8] It doesn't inhibit any cytochrome P450 enzymes. [8]
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. [16] Cysteamine enters lysosomes and converts cystine into cysteine and cysteine-cysteamine mixed disulfide, both of which can exit the lysosome. [8]
Cysteamine also promotes the transport of L-cysteine into cells. [13]
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. [8] An extended release form was approved in 2013. [26]
It is approved by the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA). [16] [8] [9] [10] [11] [27] [28]
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. [26]
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. [13]
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. [13]
Clinical trials in Huntington's disease were begun in the 1990s and were ongoing as of 2015. [13] [29]
As of 2013 [update] , it was in clinical trials for Parkinson's disease, malaria, radiation sickness, neurodegenerative disorders, neuropsychiatric disorders, and cancer treatment. [13] [ needs update ]
It has been studied in clinical trials for pediatric nonalcoholic fatty liver disease. [30]
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.
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 acute promyelocytic leukemia, it is effective only when the RARA-PML fusion mutation is present and 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.
A topical medication is a medication that is applied to a particular place on or in the body. Most often topical medication means application to body surfaces such as the skin or mucous membranes to treat ailments via a large range of classes including creams, foams, gels, lotions, and ointments. Many topical medications are epicutaneous, meaning that they are applied directly to the skin. Topical medications may also be inhalational, such as asthma medications, or applied to the surface of tissues other than the skin, such as eye drops applied to the conjunctiva, or ear drops placed in the ear, or medications applied to the surface of a tooth. The word topical derives from Greek τοπικόςtopikos, "of a place".
Pimecrolimus is an immunosuppressant drug of the calcineurin inhibitor class used in the treatment of atopic dermatitis (eczema).
Adapalene, sold under the brand name Differin among others, 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 developed adapalene.
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.
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.
Atopic dermatitis (AD), also known as atopic eczema, is a long-term type of inflammation of the skin. Atopic dermatitis is also often called simply eczema but the same term is also used to refer to dermatitis, the larger group of skin conditions. Atopic dermatitis results in itchy, red, swollen, and cracked skin. Clear fluid may come from the affected areas, which can thicken over time.
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.
Clascoterone, sold under the brand name Winlevi, is an antiandrogen medication which is used topically in the treatment of acne. It is also under development in a higher concentration for the treatment of androgen-dependent scalp hair loss, under the brand name Breezula. The medication is used as a cream by application to the skin, for instance the face and scalp.
Laser-assisted drug delivery (LADD) is a drug delivery technique commonly used in the dermatology field that involves lasers. As skin acts as a protective barrier to the environment, the absorption of topical products through the epidermis is limited; thus, different drug delivery modalities have been employed to improve the efficacy of these treatments. The use of lasers in LADD has been shown to enhance the penetration of drugs transdermal, leading to a higher absorption rate, limited systemic effects, and reduced duration of treatment. Although this technique has evolved in the past decade due to its efficacy through scientific research and clinical practice, there remain some limitations regarding the safety aspect that needs to be taken into consideration.