The document discusses sunscreen preparations. It begins by defining sunscreen and describing the different types of ultraviolet radiation from the sun. It then explains how UV radiation damages skin, noting that UVA penetrates deeper and causes long-term damage while UVB causes sunburn. The principles of how sunscreens work to absorb or reflect UV rays are described. Ideal properties of sunscreens are provided along with classifications and common active ingredients. Testing methods to evaluate sunscreen effectiveness are also summarized.

1. SUN-SCREEN
PREPARATIONS
Dr. Prashant L. Pingale
Associate Professor,
Dept. of Pharmaceutics,
GES’s Sir Dr. M. S. Gosavi College of
Pharm. Edu. and Research,
Nashik-422005

2. 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.

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

4. 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.

5. SKIN-DAMAGE II
• 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 long
term damage.

6. Radiation
Type
Characteristic
Wavelength (l)
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 l IR)
No
Sun Radiation Summary
Increasing
Wavelength

7. WHY USE SUN-SCREEN
• Too much unprotected sun exposure
leads to:
 Premature skin ageing
 Sun-burn
 Skin-Cancer

8. PRINCIPLE OF EFFECTIVENESS OF
SUN-SCREENS
I. A protective layer can be provided to the skin that
prevents the UV-rays to reach the skin either by
absorbing or by reflecting them.
– Zinc oxide and titanium dioxide both have such tendency.
– Preparations reflecting UV-rays are very effective and used
widely.

9. II. To incorporate substances in
preparations to filter the sun-rays
by absorbing medium range
UV-rays (280 mµ-320mµ)but
allowing rays of higher
wavelengths to pass.
All modern sun-tan preparations
are based on this principle and
contain such substances.
PRINCIPLE OF EFFECTIVENESS OF
SUN-SCREENS

10. UV filters (Three types)
• Organic chemical:
– compounds that absorb ultraviolet light
– oxybenzone
• Inorganic particulates:
– that reflect, scatter, and absorb UV light
– titanium dioxide, zinc oxide
• Organic particulates:
– that mostly absorb light like organic chemical compounds, but contain
multiple chromophores,
– may reflect and scatter a fraction of light like inorganic particulates,
– Tinosorb M

11. III. Biologically effective substances
can be used effectively to prevent
symptoms of inflammation with-out
reduction of tanning.
– Sunlight liberates histamine in the
the tissues-anti histaminic substances
avoid inflammation.
• HC’s and FC’s are useful in treating sun-burn
but not recommended in sun-tan preparation.
PRINCIPLE OF EFFECTIVENESS OF
SUN-SCREENS

12. IV. Substances that cause or accelerate tanning of the skin
can be applied.
– Dioxyacetone causes tanning by forming a brown complex with
the keratin of the corneal layer.
– 8-methoxypsoralene when taken 10-20 mg internally 2 hours
before exposure to the sun, accelerates tanning and avoids sun-
burn.
PRINCIPLE OF EFFECTIVENESS OF
SUN-SCREENS

13. IDEAL SUN-SCREEN CHARACTERS
 Absorb light preferentially over the range of 280 - 320mµ.
 Resistance to water
 Be stable to heat, light and perspiration.
 Preferably odorless, if mild odor: accepted by user.
 Be non-toxic, non-irritant, non- sensitizing
 Capable of retaining sunscreening property for several hours.
 Stable under condition of use.
 Non- stain
 Not be rapidly absorbed.
 Be neutral.
 Be rapidly soluble in suitable vehicles.

14. SUNSCREEN CLASSIFICATIONS
• 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

15. • Chemical
– Formulations containing one or more:
• PABA, PABA esters
• benzophenones
• cinnamates
• salicylates
• digalloyl trioleate
• anthranilates
– Mechanism: absorbs UV radiation
SUNSCREEN CLASSIFICATIONS

16. 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 (to
ensure penetration and binding to stratum corneum).
– Contact dermatitis can develop.
– May stain clothing.

17. SUNSCREEN AGENTS
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
– May penetrate less effectively than PABA
– Similar application and adverse effect
– Less staining

18. 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
and is superior to either agent used alone (200-400 nm
wavelength coverage).
– Beneficial in preventing photosensitivity reactions.
– Contact dermatitis is rare.
SUNSCREEN AGENTS

19. SUNSCREEN AGENTS
Cinnamates and Salicylates
• Minimally effective, absorb UVB spectrum.
• Generally used in combination with one of the above.

20. SUNSCREEN AGENTS
Anthranilates
– Minimally effective, absorbs UVA spectrum 250-322 nm.
– Usually combined with UVB agent to broaden spectrum.

21. SPF & Important of SPF
• SPF Value = MED (PS) / MED (US)
– MED (PS) : minimum erythemal dose for protected skin
(product applied skin)
– MED (US) : minimum erythemal dose for unprotected skin
(product not applied)

22. Types of skin & SPF
Type Description SPF Character
I Always burns easily & never tans More than 8 Sensitive
II Always burns & tans minimally 6 – 7 Sensitive
III Burns moderately & tans gradually 4 – 5 Normal
IV Burns minimally & always tans well 2 – 3 Normal
V Barely burns & tans profusely 2 Insensitive
VI Never burns & becomes deeply
pigmented
None Insensitive

23. CONTD.
• Suitable base can be used to make a final product of an aqueous or
alcoholic lotion, a fatty cream, oil, or an emulsion.
• The vehicle and selection of other components of the product may
contribute to its effectiveness.
• Certain natural oils such as coconut oil, peanut oil, muster seed oil
and olive oil have a fairly high absorption ability of UV light.
• An Anti-oxidant is to be incorporated if a natural oil is used to prevent
rancidity.

24. GENERAL PROCEDURE FOR
MANUFACTURING
• The product can be
– Simple oil type,
– Cream type,
– Lotion type,
– Aqueous solution type,
– Gel type, the general method will be different.
• Solution types, aqueous or oily, can be prepared by mixing and
dissolving the sun-screen and other ingredients in the vehicle, i.e.
water and oil. Perfume should be added all of last.
• Cream preparations are emulsion type and thus employ general
procedures of emulsion.
• Lotions can be solutions or emulsion type and can be prepared
accordingly.

25. EVALUATION
• Some special tests are also necessary for these types
of products:
• Spectrophotometric evaluation.
• Erythemal damage
• Sun-screen index
• In-vivo skin testing

26. EVALUATION
1. SPECTROPHOTOMETRIC EVALUATION:
This is basically to evaluate the UV radiation
absorption ability of the sun-screen compounds.
Using a UV Spectrophotometer and taking specific
concentration of the substance on the preparation,
molar extinction coefficient or absorbency can be
determined and compared with any other standard
substance.

27. 2.ERYTHEMAL DAMAGE:
It is important to estimate the erythemally effective
radiation or E-vitons/sq.cm., transmitted by a sun-tan
preparation.
The erythemal energy is the product of the solar energy
transmitted through the film of sun-tan preparation and
the effectiveness factor at that wave-length

28. EVALUATION
3. SUN-SCREEN INDEX:
This is evaluation of the relative screening activity of the
sun-screen compounds.
This is measurement of EXTINCTION CO-EFFICIENT (E
1%
0.1cm) at 308mµ and comparison with other.
308 mµ is the peak wavelength for effective sun-burn.

29. EVALUATION
4. IN-VIVO SKIN TESTING:
• This is a direct test on animal skin, particularly rabbit, the site
normally used is either back-side as this sites have maximum
sensitivity.
• Preparations are applied on a specific site and exposed to radiation
along with a control unprotected site, for a specified period of time.
• The effects are observed at the end of the period.
• Several factors or variables are to be taken care of during the test as
they may influence the results.
• Such variables or factors are radiation source, size of the test field,
etc.

30. ADVANCES IN SUN-SCREENS
1. Nano-sun screen.
2. Sun sport.
3. Sun-screen sprays.
4. Roll-on sun screen.
5. Sun-screen for children.
Nanosized
ZnO particles
Large ZnO
particles