SUNSCREENS

 ALL ABOUT SUNSCREENS....🌅

📍Pharmaceutical preparations that attenuate UV wavelength 

📍If not,uv rays will  interact with molecules in skin- chromophore to generate photochemical reaction.

📌Spectrum of UV radiation
*Ultraviolet (UV) radiation include UV-A and UV-B radiations.
*The primary targets of UV radiation in the skin and their corresponding effects are given below:-

UV-B (290-320 nm)

• Cause most severe damage

• Directly affects cell DNA and proteins

• Acute damage will cause sunburn

• Long-term damage will cause skin cancer

UV-A (320-400 nm)

• Penetrates deeper than UVB

• Produce reactive oxygen species(ROS)

• Cause profound immunosuppression

• Cause tanning, photoaging, skin cancers,exogenous photosensitization and many photodermatoses (including polymorphous light eruption)

📌What is "Critical wavelength"?

The wavelength below which 90% of the sunscreen′s UV absorbency occurs

📌What is a "Broad spectrum sunscreen"?

*Critical wavelength more than 370 nm 

*UVA protection factor  above 4

📌What is a "Water-resistant sunscreen"?

A  sunscreen which maintains the label SPF value after two sequential immersions in water for 20 min each (40 min)

📌What is a "Very water-resistant sunscreen?"

A sunscreen which maintains the label SPF value after four sequential immersions in water for 20 min each  (80 min)

📌In the United States, a product that has been shown to be water-resistant or very water-resistant, can also be labeled as "sweat resistant."

📍Characteristics of an ideal sunscreen:-

•Broad spectrum 

• Cosmetically elegant 

• Substantive 

• Non-irritant 

• Hypoallergenic

 • Non-comedogenic

 • Economical

📍FDA approved indications for sunscreens

 1.Sunburn. 

2.Skin/lip damage, freckling, skin discoloration.

 3.Skin aging.

 4.Skin cancer.

📍 Off-label Indications:-

1.Phototoxic/photoallergic drug reactions.

 2.Photosensitivity diseases.

 3.Photoaggravated dermatoses. 

4.Post inflammatory hyperpigmentation (post procedure)

 5.Photosensitivity diseases- ▪ Polymorphous light eruption (290-365 nm) ▪ Solar urticaria (290-515 nm) ▪ Chronic actinic dermatitis (290 nm-visible) ▪ Persistent light reaction (290-400 nm) ▪ Lupus erythematosus (290-330 nm)Xeroderma pigmentosum (290-340 nm) ▪ Albinism 

📍 Sunscreen related indices

 1. UVB sunburn protection factor (SPF).

 2. UVA protection indices. 

3. Immune protection factor (IPF).

 4. Clothing indices. 

📍 UVB sunburn protection factor (SPF)

 • The SPF is the amount of UV radiation required to cause sunburn on skin with the sunscreen on, as a multiple of the amount required without the sunscreen.

 • SPF = MED protected skin / MED unprotected skin

 •SPF and level of protection from uv B rays:-

Ultra protection - SPF 50+

 ▪ Very high protection - SPF 30-50 

▪ High protection -SPF  15-25

 ▪ Medium protection- SPF8-12

 ▪ Low protection – SPF 2-6 

📍UV-B FILTERS 

a. Aminobenzoates- PABA derivatives – Padimate O 

b. Cinnamates – Octinoxate, Cinoxate 

c. Salicylates – Octisalate, Homosalate, Trolamine salicylate 

d. Octocrylene 

e. Ensulizole 

📍UV-A filters 

a. Benzophenones (UVB and UVA2 absorbers) - Oxybenzone, Sulisobenzone, Dioxybenzone 

b. Avobenzone or Parsol 1789 (UVA1 absorber)

 c. Meradimate (UVA2 absorber) 

📍NEW GENERATION BROAD SPECTRUM (UVA+UVB)FILTERS

• Ecamsule (Mexoryl SX)

 • Silatriazole (Mexoryl XL) 

• Bemotrizinol (Tinosorb S) 

• Bisoctrizole (Tinosorb M)

📍Inorganic sunscreens 

a. Zinc oxide
b. Titanium dioxide 
c. Iron oxide
d.Red veterinary petrolatum 
e.Kaolin 
f.Calamine
g.Ichthammol 
h.Talc

 📌Sunscreen vehicles :-

• Lotions/Creams 
• Gels
 • Sprays/Aerosols
 • Sticks/waxes 

📌SYSTEMIC PHOTOPROTECTIVE AGENTS

 • “Systemic sunscreens”
 • It can be used as a complement to prevent or reduce skin damage caused by solar radiation absorption 
•Beta- Carotene •Antimalarials •Vitamin A, C, E •Selenium •Green tea tocopherol •PABA 

📌RECOMMENDATIONS FOR SUNSCREEN APPLICATION

1. Sunscreen should be applied properly to all sun exposed areas (in a concentration of 2 mg/cm2)
 2. It should dry completely before sun exposure 
3. Application should be 15minutes before sun exposure
 4. Should be reapplied every 2 hours, and after swimming, vigorous activity, excessive perspiration 

📌"Teaspoon rule" of sunscreens:-
• 3 mL (slightly more than half a teaspoon) - For each arm, face and neck
 • 6 mL (slightly more than a teaspoon) -For each leg,chest and back

📌ADVERSE EFFECTS OF SUNSCREEN
1. Subjective irritation – Stinging, burning, itching. 
2. Contact urticaria – Immunogenic, nonimmunogenic. 
3. Irritant Contact Dermatitis 
4. Allergic Contact Dermatitis
 5. Photosensitivity. 
6. Acnegenicity- Comedogenicity. 

📌Contraindications for sunscreens:-
• Known sensitivity to any active sunscreen/vehicle ingredient.
 • Infants < 6 months.

📍Sunscreen is essential for several reasons: it prevents tanning and pigmentation, slows down skin aging, helps prevent skin cancers, and is therapeutic for sun-induced dermatitis.

📍How should sunscreen be applied?

- Choose a sunscreen with an SPF (Sun Protection Factor) of 30 or higher.

- Apply sunscreen both indoors and outdoors.

- Reapply sunscreen every three hours.

📍What is the best sunscreen?

The best sunscreen depends on your skin texture, acne proneness, skin type, and the amount of sun exposure.

📍Can individuals with acne-prone skin use sunscreen?

Yes, but not all sunscreens are suitable for them. Brands like Acne UV Gel Sunscreen and Photostable Acne are some of the good options available in the market.

📍Is it possible to use sunscreen with cosmetics?

Yes, it is possible.

📍Which sunscreen is ideal for dry skin?

For dry skin, a moisturizer containing sunscreen, such as Episoft AC, is a suitable choice.

📍Is sunscreen safe during pregnancy?

Yes, sunscreen is safe to use during pregnancy.

📍Is sunscreen safe for children?

Yes, sunscreen is safe for children.

📌CONCLUSION

• Sunscreens protect us from harmful UVR and resultant complications including photoaging and carcinogenesis. 

• Classified as organic and inorganic.

 • Other photoprotective measures to be taken for complete photoprotection

 • Newer technologies – systemic sunscreen, nanotechnology,etc

 • Cost and compliance maybe the major shortcoming in Indian scenario.