First- and second-generation retinoid compounds

The retinoids are a class of chemical compounds that are related chemically to vitamin A. Retinoids are used in medicine, primarily due to the way they regulate epithelial cell growth. A chemical compound is a chemical substance formed from two or more elements, with a fixed ratio determining the composition. ... The structure of retinol, the most common dietary form of vitamin A Vitamin A is an essential human nutrient. ... In zootomy, epithelium is a tissue composed of a layer of cells. ...

Retinoids have many important and diverse functions throughout the body including roles in vision, regulation of cell proliferation and differentiation, growth of bone tissue, immune function, and activation of tumor suppressor genes. In psychology, visual perception is the ability to interpret visible light information reaching the eyes which is then made available for planning and action. ... This article is about the skeletal organs. ... A request has been made on Wikipedia for this article to be deleted in accordance with the deletion policy. ... A tumor suppressor gene is a gene that reduces the probability that a cell in a multicellular organism will turn into a tumor cell. ...

Research is also being done into their ability to treat skin cancers. Currently 9-cis retinoic acid may be used topically to help treat skin lesions from Kaposi's sarcoma. Skin cancer is a malignant growth on the skin which can have many causes. ... The Retinoids are a class of chemical compounds that are related chemically to vitamin A. Retinoids are used in medicine, primarily due to the way they regulate epithelial cell growth. ...

Types

There are three generations of Retinoids:

• First generation retinoids: which include retinol, retinal, tretinoin (Retin-A), isotretinoin and alitretinoin.

• Second generation retinoids: which include etretinate and its metabolite acitretin.

• Third generation retinoids: which include tazarotene , bexarotene and Adapalene.

Retinol, the animal form of vitamin A, is a yellow fat-soluble, antioxidant vitamin important in vision and bone growth. ... Retinal, technically called retinene1 or retinaldehyde, is a light-sensitive retinene molecule found in the photoreceptor cells of the retina. ... Tretinoin is the acid form of vitamin A and so also known as all-trans retinoic acid or ATRA. It is a drug commonly used to treat acne vulgaris and keratosis pilaris. ... Isotretinoin (INN) (pronounced or [1]) is a medication used for the treatment of severe acne. ... Alitretinoin is an antineoplastic agent. ... Etretinate (Tegison®) is a medication used to treat severe psoriasis. ... The Retinoids are a class of chemical compounds that are related chemically to vitamin A. Retinoids are used in medicine, primarily due to the way they regulate epithelial cell growth. ... Tazarotene (marketed as Tazorac®, Avage® and Zorac®) is a prescription topical retinoid sold as a cream or gel. ... Bexarotene is an antineoplastic agent. ... Adapalene is a topical retinoid primarily used in the treatment of acne and is also used (off-label) to treat keratosis pilaris as well as other skin conditions. ...

Structure

The basic structure of the retinoid molecule consist of a cyclic end group, a polyene side chain and a polar end group. The conjugated system formed by alternating C=C double bonds in the polyene side chain are responsible for the color of retinoids (typically yellow, orange, or red). Hence, many retinoids are chromophores. Alternation of side chains and end groups creates the various classes of retinoids. Polyenes are poly-unsaturated organic compounds that contain one or more sequences of alternating double and single carbon-carbon bonds. ... A chemically conjugated system, is a system of atoms covalently bonded with alternating single and double bonds (e. ... A chromophore is part (or moiety) of a molecule responsible for its color. ...

First and Second generation retinoids are able to bind with several retinoid receptors due to the flexibility imparted by their alternating single and double bonds.

Third generation retinoids are less flexible than First and Second generation retinoids and therefore, interact with fewer retinoid receptors.

Uses

Retinoids are used in the treatment of many diverse diseases and are effective in the treatment of a number of dermatological conditions such as inflammatory skin disorders^{[citation needed]}, skin cancers^{[citation needed]}, disorders of increased cell turnover (e.g. psoriasis)^{[citation needed]}, and photoaging^{[citation needed]}. Skin cancer is a malignant growth on the skin which can have many causes. ...

Common skin conditions treated by retinoids include acne and psoriasis^{[citation needed]}.

Toxicity

Toxic effects occur with prolonged high intake (in children 25,000-500,000 IU daily[citation needed]). A medical sign of chronic poisoning is the presence of painful tender swellings on the long bones. Anorexia, skin lesions, hair loss, hepatosplenomegaly, papilloedema, bleeding, general malaise, pseudotumor cerebri, and death may also occur. In medicine, a sign is a feature of disease as detected by the doctor during physical examination of a patient. ... This article is about the symptom of decreased appetite. ... Skin Lesions can include moles, cysts, warts or skin tags. ... Baldness (formally alopecia) is the state of lacking hair where it usually would grow, especially on the head. ... Hepatosplenomegaly is the simultaneous enlargement of both the liver (hepatomegaly) and the spleen (splenomegaly). ... Papilledema is optic disc swelling that is caused by increased intracranial pressure. ... For other uses, see Bleeding (disambiguation). ... Malaise is a feeling of general discomfort or uneasiness, an out of sorts feeling, often the first indication of an infection or other disease. ... Benign intracranial hypertension (BIH), also known by the obsolete term pseudotumor cerebri is a neurologic disease that is caused by increased intracranial pressure in the subarachnoid space surrounding the brain without any indication of intracranial pathology. ... For other uses, see Death (disambiguation). ...

Chronic overdose also causes an increased liability of biological membranes and of the outer layer of the skin to peel.[citation needed]

Recent research [citation needed] has suggested a role for retinoids in cutaneous adverse effects for a variety of drugs including the Antimalarial drug proguanil. It is proposed that drugs such as proguanil act to disrupt retinoid homeostasis. Antimalarial drugs are designed to prevent or treat malaria. ... Proguanil (proguanil hydrochloride) is a prophylactic antimalarial drug, which works by stopping the malaria parasite, Plasmodium falciparum and Plasmodium vivax, from reproducing once it is in the red blood cells. ... Proguanil (proguanil hydrochloride) is a prophylactic antimalarial drug, which works by stopping the malaria parasite, Plasmodium falciparum and Plasmodium vivax, from reproducing once it is in the red blood cells. ... Homeostasis (from Greek: ὅμος, homos, equal; and ιστημι, histemi, to stand lit. ...

References

• The Pharmacological Basis of Therapeutics -Goodman & Gilman 10th EDT.

• Clinical Pharmacology -P.N. Bennett & M.J. Brown

See also

• Adapalene
• Hypervitaminosis A syndrome
• Biotinylated retinoids

Adapalene is a topical retinoid primarily used in the treatment of acne and is also used (off-label) to treat keratosis pilaris as well as other skin conditions. ... Hypervitaminosis A syndrome is a condition that is caused by excessive intake of vitamin A or vitamin A analogs. ...

External links

• MeSH Retinoids