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Puvalen is a photo-sensitizing preparation. Puvalen contains two coumarins (plant chemicals that prevent blood clotting) - xanthotoxin, which is chemically 8-methoxy-6.7-coumarin, or 8-metoxipsoralen, and bergaptene, which is chemically 5- methoxy-6.7-furocoumarin.
Puvalen (Methoxsalen; Oxsoralen; Oxsoralen-Ultra) is a crystalline white powder with a yellowish nuance without smell or taste. It practically does not dissolve in water, it is difficult to dissolve in alcohol, and it is easily soluble in chloroform. It is absorbed well by the body after internal administration, and is derived from the body predominantly by the kidneys. The application of preparation is based on its ability to increase the sensitivity of the skin to ultraviolet rays, and also to stimulate the formation of melanin (skin pigment that gives skin pinkish, brownish, and black color). This effect does not appear with destructive changes in melanocytes (skin cells that produce the pigment melanin). The peak of the photo-sensitizing effect starts 1 - 3 hours after the application of 8-MOP (Methoxypsoralen).
The mechanism of action of Puvalen is not yet completely explained. Primary role is considered to be the interaction of the activated photosensitizer with DNA (Deoxyribonucleic acid - molecular carrier of genetic information) with the formation of mono-functional or bi-functional compounds, which leads to breaking of the cellular proliferation (rapid repeated production of new cells) due to temporary suppression of the synthesis of nucleic acids (large molecules composed of nucleotide subunits) and protein.
Among other mechanisms there may be the suppression of pathologic keratinization (thickening of the outer layer of the skin by overproduction of keratin), possibly due to the repression of genes, due to its influence on biosynthesis and metabolism of prostaglandins (hormone-like substances that play a part in inflammation and produce pain) and on the cellular membranes penetrability.
Indications: Puvalen (Methoxsalen; Oxsoralen; Oxsoralen-Ultra) and other derivatives or synonyms of 8-MOP (Methoxypsoralen) in combination with the long-wave ultraviolet rays (UVA) use as a Photo-Chemotherapy (PUVA) of the extended forms of psoriasis.
Counter-indications: all somatic ("bodily") illnesses in an acute stage, especially diseases of liver, kidneys, as well as the cataract (clouding of the lens of the eye), increased sensitivity to the ultraviolet rays and the solar irradiations (photo-dermatitis, solar hives etc). Puvalen is not prescribed to children younger than 18 years old, or during pregnancy.
Usage: Puvalen is prescribed orally 2 hours prior to UVA from the calculation of 0.6 mg for 1 kg of the body weight of the patient.
Common side-effects: nausea, itching and Hypertrichosis (excessive hair growth on the body).
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