Premium
TARGETED DRUG DELIVERY TO THE SKIN AND DEEPER TISSUES: ROLE OF PHYSIOLOGY, SOLUTE STRUCTURE AND DISEASE
Author(s) -
Roberts MS
Publication year - 1997
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1997.tb02708.x
Subject(s) - stratum corneum , dermis , iontophoresis , chemistry , penetration (warfare) , biophysics , drug delivery , polar surface area , permeation , permeability (electromagnetism) , transdermal , drug , passive transport , pharmacology , biochemistry , pathology , medicine , membrane , biology , organic chemistry , molecule , operations research , engineering , radiology
SUMMARY 1. Drug delivery through the skin has been used to target the epidermis, dermis and deeper tissues and for systemic delivery. The major barrier for the transport of drugs through the skin is the stratum corneum, with most transport occurring through the intercellular region. The polarity of the intercellular region appears to be similar to butanol, with the diffusion of solutes being hindered by saturable hydrogen bonding to the polar head groups of the ceramides, fatty acids and other intercellular lipids. Accordingly, the permeability of the more lipophilic solutes is greatest from aqueous solutions, whereas polar solute permeability is favoured by hydrocarbon‐based vehicles. 2. The skin is capable of metabolizing many substances and, through its microvasculature, limits the transport of most substances into regions below th. dermis. 3. Although the flux of solutes through the skin should be identical for different vehicles when the solute exists as a saturated solution, the fluxes vary in accordance with the skin penetration enhancement properties of the vehicle. It is therefore desirable that the regulatory standards required for the bio‐equivalence of topical products include skin studies. 4. Deep tissue penetration can be related to solute protein binding, solute molecular size and dermal bloo. flow. 5. Iontophoresis is a promising area of skin drug delivery, especially for ionized solutes and when a rapid effect i. required. 6. In general, psoriasis and other skin diseases facilitate drug delivery through th. skin. 7. It is concluded that the variability in skin permeability remains an obstacle in optimizing drug delivery by thi. route.