What should we know about Dandruff and its treatment.
What is Dandruff ?
Dandruff is an excessive flaking of the skin on the hairy area of the scalp, with some skin flakes caught amongst the hair, shedding of surface skin cells is normal, as they are gradually replaced with cells formed at the base of the epidermis which then move towards the surface, this process takes about a month, an increase in the number of cells being shed , which tend to clump together is called dandruff, if the scalp is excessively dry, what appears to be dandruff may just be dry flaking skin.
The causes of dandruff and dry scalp:
Dandruff (or flaky dry scalp) is an itchy, discomfort and persistent skin disorder of the scalp, today most skin specialists agree that dandruff is associated with a tiny fungus called Pityrosporum ovale. Dandruff is thought to be caused by overgrowth of Pityrosporum ovale which live on normal skin, this fungus lives on our bodies and scalp all the time, usually without causing a problem, but unfortunately for some people, the fungus increase in numbers, leading to dandruff, various environmental factors make the condition more serious, such as perspiration, climate, inadequate diet as well as stress, hormonal activity, or even a person's genetic, dandruff is often known as "dry scalp", but people with oily scalps tend to suffer most, an oily scalp supports the growth of Pityrosporum ovale. this overgrowth causes local irritation resulting in hyper-proliferation of the cells (keratinocytes) forming the outer layer of the skin, these form scales which accumulate and are shed as dandruff flakes.
Dandruff is most easily recognized as whitish scales on the scalp and red around the hair follicles, if the scales are yellow and greasier than normal dandruff scales, and your skin is red and itchy, you may have a severe form of dandruff known as seborrheic dermatitis. This may spread to other areas, for example the eyebrows, beard, or the folds around the nose.
Latest research has been focusing on the role of sebum as a cause of dandruff, sebum is the oily substance secreted by the glands around the hair follicles, it should be noted that neither dandruff nor seborrheic dermatitis occur commonly before puberty, an age when sebum production starts to be stimulated, dandruff is more common in areas where sebum production occurs, overproduction of sebum is therefore an important factor, this is why people with oily hair are more likely to suffer from a dry flaky scalp!
Treatment of dandruff:
To treat dandruff, particularly if it is severe, use medicinal which relieves severe itching, flaking, tender and inflamed scalps while leaving the hair soft, shining and manageable, pH of 5.5 will protect the cuticle of the hair, preventing further damage to the skin, once the condition has been brought under control, use antidandruff shampoo or medicated shampoo to help discourage growth of bacteria and fungi.
How does antidandruff shampoo work ?
Antidandruff shampoos work by three mechanisms, ingredients such as coal tar are antikeratostatic and they inhibit keratinocyte cell division, detergents in the shampoo are keratolytic to remove warts and other lesions in which the epidermis produces excess skin, they break up accumulation of scale, antifungal agents such as ketoconazole inhibit growth of the fungus itself, other components such as selenium sulphide also inhibit fungus growth .
Coal Tar
Coal tar is a dark brown or black liquid of high viscosity, which smells of naphthalene (camphoraceous) and aromatic hydrocarbons. Coal tar is among the by-products when coal is carbonized to make coke and coal gas. Coal tars are complex and variable mixtures of phenols, polycyclic-aromatic-hydrocarbons (PAHs), and heterocyclic compounds, The NPF states that coal tar contains approximately 10,000 different chemicals, Coal Tar can be used in medicated shampoo, soap and ointment, as a treatment for dandruff, psoriasis, and to repel head lice.
How Coal Tar works ?
It is not clear how coal tar works, it may reduce the turnover of the skin cells, reduces inflammation and have 'anti-scaling' properties.
According to the National Psoriasis Foundation and the FDA, coal tar is a valuable, safe and inexpensive treatment option for millions of people with psoriasis (psoriasis is a common skin condition which commonly develops as patches of red, scaly skin) and other scalp conditions, concentrations between 0.5% and 5% are safe and effective for psoriasis, and no scientific evidence suggests that the coal tar in the concentrations seen in non-prescription treatments is carcinogenic, contact of coal tar products with normal skin is not normally harmful, therefore, coal tar creams can be used liberally and can be used for both large plaques of psoriasis, and for widespread small patches, for some people coal tar can cause skin irritation, a contact allergy, or an acne-like rash, but this occurrence are temporary and clear if the cream is stopped. modern creams typically contain between 0.4% and 2% crude coal tar. Crude coal tar is the most effective form, mainly used in hospital skin departments, typically in a concentration of 1 to 10% in a soft paraffin base, however, it is messy and smelly to use, only few people can tolerate it. Some coal tar preparations are used to add to bath water which can also be helpful for widespread psoriasis.
Ketoconazole
Ketoconazole belongs to imidazole group, it is synthetic antifungal drugs inhibit the enzyme cytochrome P450 14α-demethylase, that converts lanosterol to ergosterol (ergosterol inhibitors / lanosterol 14 alpha-demethylase inhibitors), which is required in fungal cell membrane synthesis. Ketoconazole is used topically, it is very lipophilic which leads to accumulation in fatty tissues, ketoconazole is best absorbed at highly acidic levels, so when taken orally, antacids or other causes of decreased stomach acid levels will lower the drug's absorption.
Fluoconazole
The less toxic and more effective triazole compounds fluconazole and itraconazole have largely replaced ketoconazole for internal use.
Fluconazole (
fluconazole inhibits the fungal cytochrome P450 enzyme 14α-demethylase (ergosterol Inhibitors / lanosterol14 alpha-demethylase inhibitors), same as ketoconazole, this inhibition prevents the conversion of lanosterol to ergosterol, an essential component of the fungal cytoplasmic membrane, and subsequent accumulation of 14α-methyl sterols.
Itaconazole
Itraconazole invented in 1984, is a triazole antifungal agent, the drug may be given orally or intravenously. the mechanism of action of Itraconazole is the same as the other triazole antifungals, like ketoconazole and fluconazole, it inhibits the fungal cytochrome-P450-oxidase, mediated synthesis of ergosterol.
Zinc Pyrithione
Zinc pyrithione is a coordination complex of Zinc, while pyrithione is the conjugate base derived from 2-mercaptopyridine-N-oxide (derivative of pyridine-N-oxide), the pyrithione ligands, which are formally monoanions, are chelated to Zn2+ via oxygen and sulfur centers.
Zinc pyrithione is colorless solid as an antifungal and antibacterial agent, was first reported in the 1930s, in the crystalline state, zinc pyrithione exists as a centrosymmetric dimmer, each zinc is bonded to two sulfur and two oxygen centers. In solution, the dimers dissociate via scission of one Zn-O bond.
Its antifungal effect is proposed to derive from its ability to disrupt membrane transport by blocking the proton pump that energizes the transport mechanism, fungi are capable of inactivating pyrithione in low concentrations.
Zinc pyrithione is best known for its use in treating dandruff and seborrheic dermatitis. It also has antibacterial properties and is effective against many pathogens from the streptococcus and staphylococcus class. Its other medical applications include treatments of psoriasis, eczema, ringworm, fungus, athletes-foot, dry skin, atypical dermatitis, tinea, vitiligo.
Zinc pyrithione is approved for over-the-counter topical use in the
Selenium Sulfide
( SeS )
Selenium sulfide is an orange-yellow powder that is practically insoluble in water and organic solvents. When heated to decomposition, it emits toxic fumes of sulfur oxides (SOx) and selenium (Se).
When applied topically, Selenium sulfide in an antidandruff shampoo containing 2.5% selenium sulfide, exhibited no carcinogenic effect in mice; however, these studies were not conclusive because the length of study was limited to 88 weeks by the relatively short lifespan of the strain of mouse (NCI 197, 1980; NCI 199, 1980). There were no data available to evaluate the carcinogenicity of selenium sulfide in humans !!!
Selenium sulfide is used especially in shampoos to treat seborrhea, FDA reports that Selenium sulfide is an active ingredient in some drug products to treat dandruff and certain types of dermatitis, an antidandruff shampoo containing 1% selenium sulfide is available without prescription and is recommended for use once or twice a week, by prescription, a shampoo or lotion containing 2.5% selenium sulfide is available, with the recommended application limited to 10 minutes for 7 days to avoid the possibility of acute toxic effects, and a 2.5% aqueous suspension of Selenium sulfide has also been approved by the FDA for marketing by prescription for treatment of Tinea versicolor fungal infection.
The primary routes of potential human exposure to selenium sulfide are dermal contact, ingestion, and inhalation, residues of selenium sulfide remain
on the scalp after rinsing, although there is no substantial absorption through intact skin, absorption has been reported in patients with open lesions on the scalp or in
patients using a 1% cream on the back (NCI 199, 1980), a patient with scalp lesions that used selenium shampoos had a level of selenium sulfide as high as 32
µg/ml in her urine (NCI 194, 1980).
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