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Bioequivalence Assessment of three 0.025% tretinoin gel products: Dermatopharmacokinetic vs. Clinical Trial Methods. Lynn K. Pershing, Ph.D. Department of Dermatology University of Utah Salt Lake City, UT 84132. Common Goal Best Therapeutic Products. Physicians. FDA. Generic Industry.
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Bioequivalence Assessment of three 0.025% tretinoin gel products:Dermatopharmacokinetic vs. Clinical Trial Methods Lynn K. Pershing, Ph.D. Department of Dermatology University of Utah Salt Lake City, UT 84132
Common GoalBest Therapeutic Products Physicians FDA Generic Industry Innovator Industry Consumer Scientists Health Care Insurance CROs
Hypothesis The dermatopharmacokinetic (DPK) method will assess the BIOEQUIVALENCE of three 0.025% tretinoin gel products similar to the Clinical Efficacy/Safety Trial method
Bioequivalence How much differentcan two topical products be and still be bioequivalent?
BioequivalenceQ1 Q2 similar Q1 Q2 Qualitatively similar Quantitatively similarsame same Vehicle components [Vehicle components]
Bioavailability Q1 Q2 different Q1 Q2 Qualitatively different Quantitatively differentdifferent different [active] Vehicle components different [Vehicle components]
Bioequivalence AssessmentClinical Efficacy/Safety Acne Trial
SC Drug DispositionInfluence Of Weight Removed On Drug Concentration Gradient
Bioanalytical Assay Validation Tretinoin Isotretinoin • Recovery >89.7% >87.0% • Interferences None None • Linear regression 0.9963 0.9961 • Accuracy >87% >85% • Precision < 8% <11% • Assay parameters • Calibration stds 4-100 ng/mL 4-100 ng/mL • LOQ 4 ng/mL 4 ng/mL • Stability • Pre-extraction • -70oC storage 4 week 4 week • Benchtop 2 hrs 2 hrs • Post-extraction • Autosampler 112 hrs 112 hrs • Freeze thaw 1 cycle 1 cycle
Product Dosing: 0.025% Tretinoin Gel 250 mcL syringe
DPK Experimental Design UPTAKE ELIMINATION
Surface Area Considerations Treated Skin Site vs. Adhesive Disc
Bioequivalence Assessment of Three 0.025% tretinoin gel products
DPK Method for Bioequivalence Assessment • Objective • Sensitive • Discriminating • Precise • Accurate • Relevant • Scientifically • Clinically • Comparable PK method used for oral solid dosage products
CONCLUSIONSDPK Method for Bioequivalence Assessment 0.025% tretinoin gel • DPK results predict Clinical Efficacy Results • DPK provides mechanistic basis for Safety Results • DPK is sensitive, reproducible and valid method for BE assessment