Pharmacokinetic and local tissue disposition of [14C]sodium diclofenac following iontophoresis and systemic administration in rabbits

Journal of Pharmaceutical Sciences (Impact Factor: 2.59). 09/2001; 90(9):1269 - 1276. DOI: 10.1002/jps.1079


The systemic pharmacokinetics and local drug distribution of sodium diclofenac in skin and underlying tissues was studied. Iontophoresis facilitated local and systemic delivery of diclofenac sodium compared with passive diffusion. The maximum plasma concentration of sodium diclofenac was achieved within 1 h of iontophoresis, and the delivery was proportional to applied current density (371 ± 141 and 132 ± 62 μg/L at 0.5 and 0.2 mA/cm2, respectively). The in vivo delivery efficiency for diclofenac in rabbit was 0.15 mg/mA·h. The concentrations of sodium diclofenac in the skin, subcutanoeus tissue, and muscle beneath the drug application site (cathode) were significantly greater than plasma concentrations and concentrations of drug in similar tissues at the untreated sites. The results thus suggest that the cutaneous microvasculature is not always a perfect “sink” and that transdermal iontophoresis facilitated the direct penetration of diclofenac sodium to deeper tissues. No skin irritation was observed up to 0.5 mA/cm2 current density and 7 mg/mL sodium diclofenac concentration. © 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:1269–1276, 2001

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    • "In contrast, most of the drug found in the SF of the treated site had been delivered by direct penetration from the dosage site, with only a small portion delivered by the systemic circulation. Similar conclusions can be found elsewhere8, 10, 14. All of these observations imply that cutaneous circulation is not always an infinite “sink,” and that a drug may not be completely removed from the stratum corneum, epidermis, and dermis. "
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