Topical Skin Treatment

The skin is the largest organ of the body, where substances are constantly leaving it and many substances are trying to enter it. This huge barrier around the body is the stratum corneum, although it is the thinnest and most superficial layer of the epidermis, but it is important, and the keratin filaments produced by keratinocytes act as a barrier. They create and try to protect the body. Two layers of lipids, called lamellae, are around the keratinocytes to prevent excessive loss of body water, and the topical medicine must be fat-soluble to pass through this layer, even if it has a low molecular weight. Even if it is not soluble in fat, it can still enter.

1- Carriers : which are substances to transfer the drug to the skin, which plays a role in the strength of the drug and its effectiveness, and affects the extent of absorption and its amount, which is called bioavailability, which means that two factors are dissolved in the same amount. and in the second carrier, the ability to pass through the stratum corneum, which is related to the concentration of the drug.

2- Drug concentration : If a substance at any concentration is open in the solution carrier, by increasing the concentration, we make the product stronger, such as trothionine cream or gel, but in other cases where we have a concentration limit, adding propylene glycol increases or maintains the solubility of the drug and We increase its bioavailability.

3- Separation coefficient : low drug absorption, which is due to low penetration in the stratum corneum, and most of the drug remains on the surface and is lost by clothing or washing, etc., except for the physical and chemical factors of light, etc. substances such as ethanol or even propylene glycol cause separation of the drug from the skin.

Factors affecting the separation coefficient

Occlusio

Increases the amount of drug available to the stratum corneum with increased hydration

Different areas

Each area of ​​the skin has different permeability, depending on the thickness of the stratum corneum – the number of sebaceous glands – the hydration level of the area.

The greatest penetration and absorption is in the scrotum, then the face, head and neck, then the trunk and body, then the palms and feet, and finally the nails.

The reason for choosing topical treatment is to treat the same point of the patient in order to cause the least side effects. Until today, 20 drugs have been approved by the FDA to be used topically on the skin. They are divided into 3 categories: chemical – biochemical – and physical.

A: Chemicals included

water, carrier solutions (solvents-surfactant-liposome)

B: Biochemicals included

Peptides – hemetabolic inhibitor

A: Physical included

Thermal-mechanical-micro needle and…

Chemical enhancers are compounds that react with the lipid matrix of the stratum corneum and change the structure of N to cause more absorption. The main advantage of these substances is their cheapness and the main disadvantage is skin irritation associated with long-term use.

Biochemical enhancers directly affect permeability by changing lipid metabolism

A physical enhancer is used to increase transdermal absorption

The first category of topical drugs

They are divided into three categories according to biological activity

1- Short-term effects such as cortisone and hydrocortisone, which have a mineralocorticosteroid effect with a long biological life of about 10 hours, but a plasma half-life of 1 hour.

2- Medium effect, which includes prednisolone, prednisone, metiaprednisolone, and triamcinolone, which is a medium mineralocorticosteroid with a biological lifespan of about 30 hours and a plasma half-life of about 2 hours.

3- Long-acting, which includes dexamethasone and betamethasone, which does not have a mineralocorticosteroid effect and has a biological half-life of about 40 hours and a plasma half-life of 200 hours.

From the point of view of clinical use, they are divided into 7 categories according to the strength of the effect. The date of production of the drug and the fear of using it are two reasons for the ineffectiveness of dermal corten.

Class 1

Clobetazol : gel-ointment-cream-lotion-spray-shampoo which is 05.%

Betamethasone: gel-ointment 05.%

fluocinonide cream 01.%

Halobetasol K ointment and cream 05.%

Class 2

Betamethasone cream-lotion and ointment.5.%

Clobetazol head lotion

Flossinonide gel ointment-cream-lotion 05%

Mometasone Ointment 1%

Triamcinolone Acetate Ointment 05%

Class 3

Betamethasone, Evolution Cream 05%

fluticasone ointment 005%

Triamcinolone ointment 1% and cream 05%

Fluocinolone Acetate Ointment 025%

Betamethasone valerate foam 0125%

betamethasone solution 1.5%

Betamethasone valerate cream and solution 01%

Fluocinolone Acetate Cream 125.% and Shampoo 01.%

Fluticasone cream and solution 05.%

Triamcinolone Acetate: Ointment 025.%. Solution 025.%

Triamcinolone acetonide cream 01% and solution 025.%

Fluocinolone acetonide cream and solution 01.%

Hydrocortisone

Dexamethasone

In general, a molecule of a type of corten in an ointment carrier is stronger than a type based on Chromoseps lotion. Gel type products absorb faster.

1- Type of disease lesion

2- Location of the lesion

3- The size of the lesion

4- Features of the drug: suitable face lotion–creams are well removed—ointment for dry lesions—gel and foam for hairy areas and moist lesions

5- Mometasone and Fluticasone drugs have little skin absorption because they are quickly metabolized and excreted by the liver and have the least local or systemic side effects.

Skin atrophy and even dermatitis around the mouth – telangiectasia – stria vascular fragilitis – purpura – hairiness and acne increase the chance of infection

For this reason, strong corten should not be used on the face and wrinkled areas

The second category of topical skin treatments

Trithionines (trothionine and isotrothionine) of the first generation, which have up to 50% systemic absorption, have a half-life of 1 hour, liver metabolism and renal and biliary excretion, the therapeutic effects can be seen months later, and we expect skin irritation. Teaching the patient how to use it is very important, and start with a low concentration. And if it is tolerated and there is no local irritation, the concentration should be increased, and it should not be forgotten along with all retinoids, sunscreens and moisturizers, and instead of using abrasive cleansers, etc., it should be taken once a day in the evening. To reduce systemic side effects, it should only be used on dry skin. It should not be used by pregnant or lactating people, and it should not be used around the mouth because irritation, redness, and peeling of the skin will be seen. In the rest of the body, these side effects can be tolerated after a while. Hypo or hyperpigmentation is another side effect of retinoids, and it also causes allergic contact dermatitis.

Evolution gel and cream from all three generations are available in the market with different concentrations

And then there is second-generation etretinate, vestiotin, and third-generation adapalene in the market, which act against acne.

The third category of topical skin drugs

1- Azalic acid, which has a bacteriostatic action against Propionibacterium acnes and Aleph epidermidis, but it is also bactericidal in higher concentrations, the cream is 20% and 15% in the market, it also has anticomedonal effects, and rare complications such as hypo or hyperpigmentation have been reported.

2- Benzoyl peroxide , which is bacteriostatic against acne propion, and is available in the form of gel, cream, foam and lotion from 2.5 to 10%, and they also sell cleansing solution and shaving cream, and one of its side effects is desquamative and keratolytic.

3- Clindamycin , which is semi-active (both bacteriostatic and bactericidal) against Gram-positive cocci and anaerobes, including staph, strep, and clostridium propion.

Gavanella vaginalis covers it in the form of 1% gel, volution foam or 2% vaginal cream.

4- Erythromycin , which is a macrolide (that is, anti-inflammatory effects are added to the antibiotic effects) and works against gram-positive cocci and hemolytic β-strep and staph and gram-negative bacillus, ointment, gel, and 2% or 1.5% solution are available.

The combination of clindamycin or erythromycin with benzoyl peroxide is much more effective than either alone and reduces the risk of resistance.

5- Sodium sulfosteide, which is bacteriostatic and has keratolytic properties in addition to antibacterial, gel-cream-lotion 075.%

6- Metronidazole for anaerobes and…

7- Others include muprosin, neomycin, gentamicin, bacitovatin, and polymyxin for the treatment of surface infection, and nasal muprosin is used to destroy nasopharyngeal staph, which is recommended up to 4 times and for up to 2 weeks.

Azalic acid in the treatment of melasma

Benzoyl peroxide in bedsores and stasis ulcers

Clindomycin and erythromycin for superficial skin infection

Sulfosteide in the treatment of acne

All topical antibiotics should be applied in a thin layer on clean, dry skin once or twice a day

Allergy to any, even general urticaria

Prohibition of clindamycin in inflammatory bowel disease (probability of pseudomembranous colitis) Vivovit

Allergic contact dermatitis in the consumption of azalea cips with the consumption of any antibiotic ointment, which has been reported in up to 15% of consumers.

Folliculitis with the use of erythromycin and clindomycin

Skin irritation with benzoyl peroxide

All side effects, even poisoning and toxicity, depend on the location of the lesion and the severity of skin destruction, the degree of dryness and moisture of the skin, and the thickness of the stratum corneum layer. Babies have more absorption and more side effects.

Other factors increase absorption

 1- Low molecular size 

2-The power of lipophilicity

 3- Solubility level

 4- More concentration

 5- Base or carrier 

6- Under the dressing and covering

Apply antibiotics with a layer of less than half a millimeter on the surface of the skin – more is useless – 1 gram is enough for 10 x 10 square centimeters.

Liquid form

Monophasic solutions that are liquids

1- The pure blue type , which is the evolution gel

2- Alcoholics : pints

3- Oily

A: Oil in water is washed off with water

B: Water in oil that cannot be removed by washing with water

4-Foam

Ointment with water. Ointment without water

Monophasic hydrogel

Multiphase emulsion

Paste (paste) which is a suspension with high concentration

Powders such as zinc oxide – talc – titanium oxide

Selection based on the type of lesion

It is recommended to choose the type of basic drug carriers in the following way

1- Inflammatory dermatosis with crust: ointment and cream with wet compress and wet cover

2- Dermatoses of fishri or urode, because we have an open wound, alcohol base or salicylate should be avoided so that it doesn’t hurt and itch.

Select by location

1- No hair: Emulsion cream ointment

2- Wrinkled areas: cream solution

3- Hairy areas: foam lotion, gel and oil

Anthralin, Lindane, Tazorotan, Menthol, Salicylate, Podoniline and…

Babies have 4 times more absorption, the risk of poisoning is due to the PH of the stratum corneum, more absorption, and less hepatic metabolism, less renal excretion, and less combination with serum plasma, and even the risk of crossing the brain barrier.

anti-itch

1- Paramoxin, which is mainly combined with hydrocortisone, and is available as a gel, lotion, cream, and even ointment and foam, which works by blocking nerve endings, is also an analgesic, and is used in uremia itching, nostalgia itching, paraesthesia, and anal itching.

Complications :

Allergic contact dermatitis

2- Menthol, which has cream, ointment and gel, relieves pain and itching by cooling, and there is a possibility of contact dermatitis.

3- Phenol, which is a cooling agent, but it is prohibited for use during pregnancy and under 6 months, it may cause redness and irritation of the skin.

4- Open camphor gives cooling and local anesthesia. It rarely irritates

5- Capsaicin, which causes a burning sensation at first, but after a week, it has an anti-itching effect, and in neuralgia after herpes, kidney itching (uremic failure) and psoriasis.

Pay attention to wash your hands after use to reduce contact dermatitis and damage to eyes and mucous membranes

6- Doxypin cream in atopic dermatitis, chronic nomular eczema, simplex, although it rarely causes contact dermatitis, in narrow-angle glaucoma and urinary retention, it is prohibited in combination with neuromuscular blockers and pregnant women.

7- Diphenhydramine cream is 1% lotion and gel, it is no longer used due to high contact dermatitis.

Sunscreen or sun screen

Substances that weaken the wavelengths that cause a chemical reaction in the skin molecules, so the rays inhibit the photobiological reaction so that the living cell is not damaged.

The effectiveness of sunscreens is calculated with the sun protection factor SPF, which is the fraction of the minimum dose that causes erythema in the denominator, and the minimum dose that causes erythema without using sunscreen.

For example, SPF 10 means that it takes 10 times as much time to create a lesion as compared to not using it, and this means that it reduces erythema by 90%, and if it becomes SPF 20, the effect is no longer doubled, and it gives 92.5% protection, and a score of 30 reaches 95%, and a score of 40 means Protection reaches 97.5%

In the labeling of sunscreens, it should be noted that:

Its name should be anti-sunburn and the amount of UVB protection should be included, and in the case of UV A, its intensity varies from 1 to 4.          

UV B suppresses immunity and causes sunburn and even SCC

The amount of consumption of 2 tablespoons or 30 CC for the whole skin of an adult is likely to cause slight irritation with redness or contact dermatitis, and the good effect of these sunscreens reduces vitamin D, but not to an abnormal level, but the consumption of vitamin D is a serious recommendation. He gets wet and avoids the sun even though he wears sunscreen.