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IN VIVO STUDIES FURTHER DETAILS


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In Vivo Study No: 131

METHODS

ChemicalMembraneConcentration mg/mlConcentration mg/mlloading (mg/cm2)SpeciesSiteArea (cm2)Occluded?Exposure Time (h)Analytical Method
Caffeine0.05550.20.00222AcetoneHumanArm526HPLC

RESULTS

Length of Study (h)% Recovery+/-Dose remaining on surface (mg)% remaining on SurfaceDose remaining in stratum corneum (mg)% remaining in stratum corneumDose remaining in the viable skin% remaining in the viable skinAmount Absorbed (mg)% Absorbed+/-% Absorbed
   91.041.560.000443.96  0.0049844.87.79344.8
Maximal Flux (mcrg/cm2/h)Average Flux (mcrg/cm2/h)+/-Time Plasma/Blood Levels Peaked (h)Peak Blood Concentration (mg/l)nkp (cm/h)Lag Time (h)
 0.95314.5  12  

NOTES

In the paper they calculated the Kp as 9.53E-8. I cannot see how they came to this conclusion so I have left that off the database.They worked out the absorption by measuring the difference between applied and recovered amounts from the skin surface. The unabsorbed drug was randomely recovered at 0.25, 0.5, 1, 2, 3, 4, 5, and 6h after treatment. No biomonitoring was done. The amount left in the Stratum corneum was established in different experiments by tape stripping.

REFERENCE

Surface Recovery and Stripping Methods to Quantify Percutaneous Absorption of Caffeine in Humans (1993) J. Pharm. Sci., 82 :1099-1101