Developing Clinical Studies for Successful Regulatory Filing

1. Developing Clinical Studies for Successful Regulatory Filing Poohglin Tresukosol, M.D. Institute of Dermatology December 2009

2. Scopes • Allergenicity/Sensitizing • Anti-aging • Comedogenicity • Irritation/Anti-irritation

3. The Skin • … in numbers: • 16% of body weight (= largest organ of the human body) • Area = 1.8 m² • 3 million cells per cm² • Epidermis regenerates every 4 weeks • Water 70% within the human body vs. 10% water in the top layer of the stratum corneum

4. The Skin • Functions: • Barrier between the body and the environment • Controlling of moisture movement into and out of the body • Mediation of sensory experiences • Assistance in temperature control • Protection from ultraviolet radiation • Synthesis of Vitamin D

5. How can we study? • In vitro • In vivo • Animal model • Human model

6. COLIPA European Cosmetic Trade Association • The testing of cosmetic products is conducted using volunteers from the same population in which they are intended to be marketed in ( e.g. in terms of sex, age, ethnic origin and skin type ). The effect of population diversity on skin irritation. CD 2006:55:357-363

7. Scopes • Allergenicity/Sensitizing • Anti-aging • Comedogenicity • Irritation/Anti-irritation

8. การทดสอบความสามารถในการก่อภูมิแพ้การทดสอบความสามารถในการก่อภูมิแพ้ • The Maximization test: standard method • Skin sensitization • Animal model • Human test

9. การทดสอบความสามารถในการก่อภูมิแพ้การทดสอบความสามารถในการก่อภูมิแพ้ • Avialable human test • Schwartz-Peck test • HRIPT • Draize test • Shelanski-Shelanski test • Voss-Griffith test • Modified Draize test • Human maximization test

10. Allergenicity of substance Challenging test Resting period 2 weeks Sensitizing period

11. Allergens of the year • 2003 Bacitracin • 2004 Cocamidopropyl betaine • 2005 Steroid • 2006 PPD • 2007 Fragrance • 2008 Thiourea Dr.David AAD 2006 Dermatitis 2007;18(1):3-7

12. Sensitizers in Cosmetics • Fragrances • Preservatives • Parahydroxybenzoic acid (PHBA); minimal sensitizer J Eur Acad Dermatol Venereol 2007 Sep;21 Suppl 2:9-13

13. The Provocative Use Test or Open Test • valuable in confirming positive reactions • suspected material is rubbed directly on to normal skin (anticubital fossa) twice daily for 1 wk; 3 cm2 area • no reaction = negative • false negative reaction are common • for contact urticaria : 15-30 min. reading; retroauricular area or outer aspect of arm immediately above the elbow Fisher’s CD; 6th ed.

14. Scopes • Allergenicity • Anti-aging • Comedogenicity • Irritation/Anti-irritation • Sensitizing

15. Wrinkle: Mechanical Methods for Evaluating Skin Surface Architecture • Profilometric methods • Two-dimensional methods • Scanning electron microscopic methods • Confocal microscopic methods • Three-dimensional methods J Derm Sciences 2001;27:S5-S10

16. Wrinkle: Mechanical Methods for Evaluating Skin Surface Architecture • Profilometric methods • Mechanical tracing analysis • Laser tracing analysis J Derm Sciences 2001;27:S5-S10

17. Wrinkle: Mechanical Methods for Evaluating Skin Surface Architecture • Two-dimensional methods • Image analysis • Gray levelanalysis J Derm Sciences 2001;27:S5-S10

18. Wrinkle: Two-dimensional methods: Image Analysis Photographing Projecting angle; 30 degree Lens magnification; X15 Setting the area measured Binalization Noise elimination Area ratio calculation J Derm Sciences 2001;27:S5-S10

19. Wrinkle: Mechanical Methods for Evaluating Skin Surface Architecture • Three-dimensional methods • Light cutting analysis • Grating projection analysis J Derm Sciences 2001;27:S5-S10

20. Wrinkle: Three-dimensional methods: Principle of Light Cutting Analysis J Derm Sciences 2001;27:S5-S10

21. Wrinkle: Mesurement of 3-D pattern: Light Cutting Analysis J Derm Sciences 2001;27:S5-S10

22. Scopes • Allergenicity • Anti-aging • Comedogenicity • Irritation/Anti-irritation • Sensitizing

23. Comedogenicity Concept Comedogenic Assays : • Rabbit ear model ( ultra-sensitive ) • An improved rabbit ear model • Human model J Am Acad Dermatol 2006;54:3 Arch Derm 1982,118 BJD 1979;100:699 Cutis 1976;17:344

24. Human Model • The test substances are applied under occlusion for one month to the upper part of the backs of young adults, black men who have large follicles • The degree of follicular hyperkeratosis • Non-invasive “follicular biopsy” techniques Arch Dermatol 1982;118:903.

25. Human model • Human model could be used to evaluate comedogenicity, however the result were dissimilar from those observed in the rabbit ear model. Draelos ZD. J Am Acad Dermatol 2006;54:No3

26. Human model • A percent change from baseline was calculated: degree of microcomedone formation • A percent change in micromedone of greater or less than 10% of neg. control : noncomedogenic Draelos ZD. J Am Acad Dermatol 2006; 54:No3

27. Human model • The controversial aspect of any model is definition of the end point • Human model has strengths and weaknesses • Test material applied under occlusion • Selection of prominent of follicular orifice • This is but one of many tests used by manufacturers to determine safety Draelos ZD. J Am Acad Dermatol 2006; 54:No3

28. Comedogenicitiy of Sunscreen • UVB & UVA radiation would regularly enhance the formation of comedones when acnegenic substances were applied to the external ear canal of the rabbit • Patients who experienced summertime exacerbations of acne were frequently heavy user of sunscreens Arch Dermatol 1982;118: June

29. Comedogenicitiy of Sunscreen • UV dose : Solar-Simulating Radiation • two MEDs at wk1 Monday, Wednesday, • Three MEDs at wk2 Friday • Grading scale for the degree of comedone formation from 0 to 4 • 0 None • 1 Slight • 2 Moderate • 3 Strong • 4 Severe Arch Dermatol 1982;118:June

30. Strategies for skin irritation • The assessment of the skin corrosion and skin irritation potential of chemicals and finished product is an essential part of the toxicological evaluation prior to manufacture, transport or marketing Robinson MK. Annal New York Academy of Sciences

31. Predictive irritancy testing (1) • Predictive irritancy testing involves specific tests for the irritant potential of individual chemicals as well as test for individual susceptibility to irritation Irritant dermatitis: Derm Clin

32. Predictive irritancy testing (2) • Bioassay • In vitro skin irritation Irritant dermatitis: Derm Clin

33. Bioassays of irritation skin Measuring subtle degree of noninflammatory skin damage • Transepidermal water loss ( TEWL) • Electrical impedance • Rates of CO2 emission • Chloride ion flux Irritant dermatitis: Derm Clin

34. Skin irritation/corrosion potential • Animal model • Rabbit Draize Test • Chamber scarification test • Human model • Human 4-hour patch test • 21-day cumulative irritation test • Soap chamber test • Modified soap chamber test • Cup shake test CD 1996:34:204-212 The irritant contact dermatitis syndrome : Toxicology

35. Anti-irritants • The irritant potential of known eye and skin irritant components of formulating skin care products varied greatly depending on components of the formulation CD 2006;55:148-154

36. Anti-irritants • Goldemberg: Anti-irritants (AIs) “ Agents that used in conjunction with skin or eye irritants, reduces their irritant potential sufficiently CD 2006;55:148-154

37. Anti-irritants • Possible mechanisms of AIs • Elimination of irritancy • Reduce spread of the irritants: Prevention of complete contact with skin • Blocking of skin-reactive sites by oily substances to the skin prior to application of aqueous irritants CD 2006;55:148-154

38. Anti-irritants • AIs as treatment modalities: mechanism • Anti-inflammatiory • Stabilization of the stratum corneum lipid barrier CD 2006;55:148-154

39. AIs as Treatment Modalities for Acute Irritation • 24-hours Patch Test • Cumulative Irritation Model: more relevant for efficacy CD 2006;55:155-159

40. SPF / UVB MED of the sun screen – protected skin MED of the unprotected skin Minimal Erythematous Dose

41. PPD / +++ / UVA

42. Overview Eur J Pharmaceitics Biopharmaceutics 2009;72:295-303

43. Thank you