Transdermal use of phosphorodiamidate morpholino oligomer AVI-4472 inhibits cytochrome P450 3A2 activity in male rats.
OBJECTIVE
To determine if dermal absorption of an antisense phosphorodiamidate Morpholino oligomers (PMO) can inhibit target gene expression in the liver in vivo.


METHODS
Antisense PMO targeted to cytochrome P450 (CYP) 3A2 was applied topically to adult male rats at doses of 0.03, 0.3, and 3.0 mg. CYP3A enzyme activity in the underlying skin and liver was evaluated 24 h following application.


RESULTS
Systemic PMO bioavailability was determined by detection of full-length PMO in liver and fluorescence micrography in underlying skin. CYP3A enzyme activity were measured by hydroxylation of 7-benzyloxy-4-(trifluoromethyl)-coumarin and data were expressed as nanomoles of product/ 100 microg S9 protein/h. A topical dose of 0.03 mg inhibited enzyme levels from 576 +/- 17 (vehicle) and 564 +/- 20 (control PMO) to 432 +/- 20 in the antisense-treated liver (p < 0.05). Increasing the dose to 0.3 mg further inhibited enzyme level to 278 +/- 13 (p < 0.005). The inhibition did not increase further when the dose was increased to 3 mg. In the skin, starting enzyme levels were approximately one third of the liver (171 +/- 9) and maximum inhibition was reached at a lower dose. Topical delivery of 0.03 mg led reduced skin enzyme levels in half to 89 +/- 32 (p < 0.05). Increasing the dose to 0.3 mg and 3.0 mg did not produce any further inhibition, at 73 8 and 72 +/- 17 respectively.


CONCLUSIONS
Topical application of antisense PMO in rats is a feasible delivery strategy for gene targets in liver and underlying skin.
Arora
Vikram
V
AVI BioPharma, Corvallis, Oregon, USA.
Hannah
Tracy L
TL
Iversen
Patrick L
PL
Brand
Rhonda M
RM
D000279:Administration, Cutaneous; D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051544:Cytochrome P-450 CYP3A; D016503:Drug Delivery Systems / Q000379:methods*; D004791:Enzyme Inhibitors / Q000008:administration & dosage*; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008297:Male; D008565:Membrane Proteins; D051379:Mice; D008812:Mice, Hairless; D008969:Molecular Sequence Data; D009025:Morpholines / Q000008:administration & dosage*; D060172:Morpholinos; D051381:Rats; D017207:Rats, Sprague-Dawley
D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D009025:Morpholines; D060172:Morpholinos; D001189:Aryl Hydrocarbon Hydroxylases; C465260:Cyp3a2 protein, rat; D051544:Cytochrome P-450 CYP3A