ASTRINGENTSIRRITANTS__COUNTER-IRRITANTS_AND_KERATOLYTICS.pptx

Astringent irritant,keratolytics

1. ASTRINGENTS,IRRITANTS , COUNTER-IRRITANTS AND KERATOLYTICS. -----Drugs acting on skin and mucous membranes.

2. ASTRINGENTS Astringents are substances that precipitate proteins, but do not penetrate cells, affecting the superficial layer only. They toughen the surface making it mechanically stronger and decrease exudation.

3. Tannic acid and tannins Found in tea, nutmeg, areca nut/betel nut. Denature proteins forming protein tannate. Other uses include: Bleeding gums-as glycerine of tannic acid. Bleeding haemorrhoids- a tannic acid suppository. Alkaloid poisoning- precipitates ingested alkoids as tannates.

4. Alcohol Ethanol and Methanol are good astringents at 50-90% concentration. Denatured spirit is used on skin to prevent bedsores, not applied on sores. Ethanol is also used as after shave & for minor cuts

5. Mineral astringents Heavy metal ions are astringent and antiseptic Alum has been used as after shave and as local haemostatic on minor cuts. Other salts of aluminium, zinc, zirconium are used as antiperspirants. They diffuse through the sweat ducts, reduce secretion from glands and partially block the ducts as well. Their antibacterial action prevents decomposition of sweat by bacteria ,reducing body odour.

6. Irritants Irritants stimulate sensory nerve endings and induce inflammation at the site of application. They produce ,, cooling warmth ,pricking tingling , hyperesthesia and local vasodilation. RUBEFACIENTS- cause local hyperemia with little sensory component . VESICANTS- increase capillary permeability cause collection of fluid under the epidermis .

7. Counter-irritants Certain irritants also produce a remote effect which tends to relieve pain and inflammation in deeper organs

8. Mechanism of counterirritants.

9. Examples :- Turpentine oil-used in form of liniment or stupes. Clove oil- cotton swab for toothache Eucalyptus oil- pain balms Camphor- cooling sensation-relieves itching. Mustard seeds Capsicum(chilli) Cathridrin Methyl salicylate (oil of wintergreen)

10. Common combinations: Vicks vaporub: methanol, camphor, thymol, turpentine oil. Relaxyl: capsicum oleoresin, mephensin, methyl nicotinate. Relispray: winter green oil, clove oil, methanol, nilgiri oil, camphor, cinnamon oil, turpentine oil. Iodex: methylsaclicylate, iodine, non-staining ointment.

11. KERATOLYTICS Dissolve the intercellular substance in the horny layer of skin. Epidermal cells swell, soften and then desquamate. U sed in hyperkeratosis lesions like corns, warts, psoriasis, ringworm, etc.

12. Salicylic acid 10%-20% solution in alcohol or propylene glycolused to treat corns. More effective when applied under occlusive dressing Mildly antiseptic and antifungal. Resorcinol Antiseptic, antifungal, keratolytic. 3-10% for eczema, seborrheic dermatitis, acne and ringworm.

13. Urea Applied at con entration of 5-10% in cream or ointment base. Acts as a humectant by its hygroscopic and water retaining property. Causes softening and solubilisation of keratin in hyper keratinised lesions like icthyosis, lichen planus. Inclusion of urea enhances the penetration of the concurrently applied topical steroid.