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Transdermal Drug Delivery – Assessment of in vitro skin permeation. Shashank Jain. Introduction. Transdermal and t opical drug delivery Advantage- Site specific application First pass metabolism Avoid GI side-effects Controlled drug delivery Non-invasive Limitation- Dose
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Transdermal Drug Delivery – Assessment of in vitro skin permeation Shashank Jain
Introduction • Transdermal and topical drug delivery • Advantage- • Site specific application • First pass metabolism • Avoid GI side-effects • Controlled drug delivery • Non-invasive • Limitation- • Dose • Large molecules • Skin irritation and metabolism • Rate limiting stratum corneum
Pathways for drug permeation Stratum corneum Epidermis Dermis Blood supply
Approaches • Physical: • Microneedle • Iontophoresis • Electrophoresis • Chemical: • Ethanol • PEG • Colloidal: • Liposome • Ethosomes • Microemulsion
Ethosome Mechanism of skin delivery via ethosomevesicles*
Assessment of in-vitro permeation • Fick’s law of diffusion
In-vitro experiment setup A] Side-Bi-Side
In-vitro experiment setup(contd.) B] Vertical Franz
In-vitro experiment setup (contd.) C] Flow Through Cells:
In-vitro permeation study procedure • Step 1. Skin selection • Human skin • Animal skin • Human skin equivalent • Step 2. Isolating skin section • Step 3. Experimental setup • Mounting skin section • Temperature • Air bubble • Step 4. Sampling • Step 5. Drug deposition study • Step 6. Data analysis • Permeation flux • Cumulative drug permeation • Drug deposition
A typical permeation profile Cumulative drug permeated/area Time
References: • Naik, A., Kalia, Y.N., Guy, R.H., 2000. Transdermal drug delivery: overcoming the skin’s barrier function. Pharmaceutical Science & Technology Today 3, 318-326 • Verma, P., Pathak, K., 2010. Therapeutic and cosmeceutical potential of ethosomes: An overview. J Adv Pharm Technol Res 1, 274-282 • http://www.permegear.com/primer.pdf • Bolzinger, M.-A., Briancon, S.p., Pelletier, J., Chevalier, Y., 2012. Penetration of drugs through skin, a complex rate-controlling membrane. Current Opinion in Colloid & Interface Science 17, 156-165.
Document BA/BE in order of preference are (1) pharmacokinetic (PK) measurements based on measurement of an active drug and/or metabolite in blood, plasma, and/or urine; (2) pharmacodynamic (PD); (3) clinical trials; and (4) in vitro studies. • The BA/BE determination based on PD (or clinical) and dermatokinetics. • DPK encompasses drug concentration measurements with respect to time, based on a stratum corneum concentration-time curve • Topical: If two formulation produce comparable stratum corneum concentration-time curves may be BE • A plot of stratum corneum drug concentration versus a time profile should be constructed to yield stratum corneum metrics of Cmax, Tmax and AUC. • Transdermal delivery systems, are considered to be bioequivalent if they yield comparable bioavailability-based plasma concentration–time profiles when administered to the same individuals under similar dosage conditions. • Two oral or transdermal formulations are judged BE if they produce comparable plasma concentration-time curves.