The free acid of Inkey Salicylic Acid is used topically to treat skin conditions, while many esters and salts of salicylic acid are absorbed through the skin or taken internally to treat other conditions. Therefore, the effect of salicylic acid is largely dependent on the route and form of administration. Salicylic acid, on the other hand, has a broad range of actions that can be divided into 10 different actions.
(1) Inkey Salicylic Acid has antibacterial effect on fast purple positive and negative bacteria, pathogenic yeast, skin mold, etc. at very low concentration (≤0.3%W/W). At a slightly higher concentration (about 10 times the minimum inhibitory concentration), it has a bactericidal effect on stationary and multiplying microorganisms. Salicylic acid has been used in recent years as a broad-spectrum microbiologically safe, well-tolerated, colorless skin antibacterial agent.
(2) When the concentration is 0.1% (W/W) or above, salicylic acid has obvious acidogenic effect on the skin surface.
(3) The same concentration of salicylic acid has anti-light effect, which is equivalent to 60% absorption rate of ammonia benzoic acid.
(4 and 5) Also at low concentrations, especially in dermatological topical solutions, salicylic acid has superficial astringent and antipruritic effects.
(6) When the dosage form and concentration are appropriate, salicylic acid also produces direct anti-eczema and anti-inflammatory effects. In guinea pigs, dermatitis is induced by ultraviolet rays, and the local anti-inflammatory effect of salicylic acid is equivalent to 63-66% of phenylbutazone or indomethacin, about 77% of acesalic acid, and about 82% of hydrocortisone.
(7) At concentrations of 5% and above (adjusted according to the special type of excipient, the way of use, that is, open or closed, and the duration of treatment), salicylic acid has a rapid and deep keratolytic effect on the stratum corneum . Finally there is exfoliation, causing skin maceration and epidermolysis.
(8) Ointment with a concentration of 1% to 4% has the effect of keratin dispersing and surface keratin separation, causing scaling release (that is, scaling off and elimination of scabs). Anti-hyperkeratotic (keratin stabilization) and anti-parakeratotic effects, normalize the process of keratinization.
(9) Since salicylic acid has a keratin-diffusing (“softening”) effect on the stratum corneum, i.e., superficial keratolytic effect, and keratolytic effect at high concentrations, salicylic acid can promote simultaneous or subsequent topical use of other drugs penetration.
Inkey Salicylic Acid concentrations between 0.5% and 2% (even above 5%) in paste and ointment formulations have a keratinizing or stabilizing effect. But so far, there is no satisfactory explanation for the pharmacokinetics of this effect. This may be due to the adaptation phenomenon of quasi homoeopathic, in which relatively weak keratolytic stimuli can lead to increased reactive keratinization.
(10) The epidermal formation effect of Inkey Salicylic Acid, especially its anti-epidermal hyperplasia effect, is still largely unexplained. The author used 3% salicylic acid ointment, which can be seen to inhibit the pathological excessive epidermal hyperplasia, which is similar to the external application of corticosteroids, and has a synergistic effect with external application of corticosteroids. In contrast, Marks et al. used (2-12 %) salicylic acid ointment and obtained opposite results on healthy human skin, and they reported an increase in epidermal formation proportional to the topical salicylic acid concentration. Theoretically, the two reactions can be coordinated with the action of the material on the corner layer. Partial loss of the stratum corneum stimulates keratinocyte proliferation. However, the keratolytic effect can be accompanied by salicylic acid inhibiting the regeneration or vitality of the spinous cell layer. This is true at least at the site of pathological proliferation or at concentrations below 5% w/w that do not produce strong keratolytic or epidermal (exfoliation) effects.