Sun Protection (Classification of Sunscreen and SPF)

Sun protection
Classification of Sunscreen And SPF
Shivam Pharmaceutical Studies and
Research Centre, Anand
Prepared by:
Rahul Kushwaha

Introduction
 In the past, sun exposure was thought to be a healthy benefit of
outdoor activity
 Overexposure to sunlight is widely accepted as the underlying cause
for harmful effects on the skin, eye and immune system
 Sun protection is essential to skin cancer prevention - about 90
percent of non-melanoma skin cancers and about 86 percent of
melanomas are associated with exposure to UV radiation from the
sun.

 Sunlight reaching the surface of the earth contains:
✓ Visible rays
✓ Ultra-violet rays
✓ Infra-red rays
 UV Rays (particularly wave-length below 320mu) are responsible
for most of the therapeutic as well as noxious effects that we
attribute to sun-light.

SKIN-DAMAGE
 The UV Spectrum is broken into three parts:
✓ Very High Energy (UVC)
✓ High Energy (UVB)
✓ Low Energy (UVA)
 Visible and IR radiation don't harm the skin.

SKIN-DAMAGE
 Very High Energy Radiation (UVC) is
currently blocked by the ozone layer.
 High Energy Radiation (UVB) does the more
immediate damage.
 But Lower Energy Radiation (UVA) can
penetrate deeper into the skin, leading to
longterm damage.

Sun Radiation Summary
Radiation
Type
Characteristic Wavelength (λ) Effects on Human Skin Visible to Human Eye?
UVC ~ 200-290 nm (Short-wave UV) DNA Damage NO
UVB ~ 290-320 nm (Mid-range UV)
Sunburn
DNA Damage
Skin Cancer
NO
UVA ~ 320-400 nm (Long-wave UV)
Tanning
Skin Aging
DNA Damage
Skin Cancer
NO
Vis ~ 400-800 nm None Currently Known YES
IR ~ 800-120,000 nm Heat Sensation (high λ IR) NO

SUNSCREEN
Definition:
 Sunscreen (also known as sunblock or suntan lotion is a lotion,
spray, gel or other topical product that absorbs or reflects the
sun's ultraviolet (UV) radiation and protects the skin.

IDEAL SUN-SCREEN CHARACTERS:
Absorb light preferentially over the range of 280 - 320mu.
Resistance to water
Preferably odorless, if mild odor: accepted by user.
Be non-toxic, non-irritant, non- sensitizing
Capable of retaining sunscreening property for several hours
Not be rapidly absorbed
Be rapidly soluble in suitable vehicles.
SUNSCREEN

Classification of Sun screen
Depending on the mode of action, sunscreens can be classified into:
1) Physical sunscreens (those that reflect the sunlight)
2) Chemical sunscreens (those that absorb the UV light).
Physical
 Opaque formulations containing:
 titanium dioxide
 talc, kaolin
 zinc oxide
 ferric chloride
 Icthyol, red petrolatum
 Mechanism: scatters or reflects UV radiation due to large particle
size

Classification of Sun screen
Chemical
 Formulations containing one or more:
 PABA, PABA esters
 benzophenones
 cinnamates
 salicylates
 digalloyl trioleate
 anthranilates
 Mechanism: absorbs UV radiation

SUNSCREEN AGENTS
PABA(Para-amino benzoic acid)
 Very effective in the UVB range (200-320 nm)
 Most effective in conc. of 5% in 70% ethanol
 Maximum benefit when applied 60 minutes prior to exposure
 Contact dermatitis can develop. May stain clothin
 May stain clothing
PABA Esters (Padimate A, Padimate O, Glyceryl PABA)
 Also very effective in UVB range (280-320)
 Most effective in conc. 2.5-8% in 65% alcohol
 Less staining

SUNSCREEN AGENTS
Benzophenones (oxybenzone, dioxybenzone, sulisobensone)
Slightly less effective than PABA
Absorbs from 250-400 nm spectrum (i.e, UVA & UVB).
Combined with PABA or PABA ester improves penetration
Beneficial in preventing photosensitivity reactions

SUNSCREEN AGENTS
Cinnamates and Salicylates
 Minimally effective, absorb UVB spectrum.
 Generally used in combination with one of the above
Anthranilates
 Minimally effective, absorbs UVA spectrum 250-322 nm.
 Usually combined with UVB agent to broaden spectrum.

Sun Protection Factor
 The term "sun protection factor" was adopted by the FDA to
describe the effectiveness of Sunscreens.
 SPF is a measure of how much solar energy (UV radiation) is
required to produce sunburn on protected skin
 (i.e., in the presence of sunscreen) relative to the amount of solar
energy required to produce sunburn on unprotected skin.
 As the SPF value increases, sunburn protection increases.
 SPFdefined as the UV energy required in producing a minimal
erythemal dose (MED) on protected skin, divided by the UV energy
required to produce a MED on unprotected skin

SPF =
𝑀𝑖𝑛𝑖𝑚𝑎𝑙 𝑒𝑟𝑦𝑡ℎ𝑒𝑚𝑎𝑙 𝑑𝑜𝑠𝑒 𝑖𝑛 𝑠𝑢𝑛−𝑠𝑐𝑟𝑒𝑒𝑛 𝑝𝑟𝑜𝑡𝑒𝑐𝑡𝑒𝑑 𝑠𝑘𝑖𝑛
𝑀𝑖𝑛𝑖𝑚𝑎𝑙 𝑒𝑟𝑦𝑡ℎ𝑒𝑚𝑎𝑙 𝑑𝑜𝑠𝑒 𝑖𝑛 𝑎 𝑛𝑜𝑛−𝑠𝑢𝑛𝑠𝑐𝑟𝑒𝑒𝑛 𝑝𝑟𝑜𝑡𝑒𝑐𝑡𝑒𝑑 𝑠𝑘𝑖𝑛
Broad-spectrum sunscreen gel can protect your skin
Sunburn
Suntan
Photo-aging
Dull complexion
Skin inflammation and Skin Cancer (more severe cases)
Sunscreens have a number written as Sun Protection Factor, i.e. SPF 15,
20, 30 or 50 on the pack

Protection level SPF value
Low protection 6,10
Medium protection 15,20,25
High protection 30,40
Very high protection 50+
Sun protection factor classification

When to re-apply the sunscreen
SPF Tab SPF/time to re-apply the sunscreen
[approx]
15 After 1 hour
30 After 2 hour
50 After 4 hour
70 After 6 hour
If you are exposed to sun
and pollution for longer
duration then you need to
re-apply your sunscreen.
SPF wise re-applying time is
mentioned in the table:

SPF Factor Percentage of UVB Rays Blocked
SPF 2 50 %
SPF 4 75 %
SPF 10 90 %
SPF 15 93 %
SPF 30 97 %
SPF 50 98 %
SPF 70 98.5 %
SPF 100 99 %

Sun Protection (Classification of Sunscreen and SPF)

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Sun Protection (Classification of Sunscreen and SPF)