Talk:First pass effect

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Oh Really?[edit]

Alternative routes of administration like suppository, intravenous, intramuscular, and sublingual avoid the first-pass effect because they allow drugs to be absorbed directly into the systemic circulation.

How would a suppository bypass the hepatic portal? The inferior mesenteric vein serves the rectum. --70.131.113.133 (talk) 04:33, 24 September 2008 (UTC)[reply]

Rectal delivery of drugs may indeed be subjected to first-pass metabolism, depending on the site of absortion within the rectum (de Boer and Breimen, 1997, Advanced Drug Delivery Reviews, 28, pp. 201-227) 79.221.83.234 (talk) 20:05, 24 January 2009 (UTC)[reply]

Drugs administered rectally enter the the systemic circulation without passing through the liver, an advantage for drugs significantly inactivated by the liver following oral route absorption (York, P. 2007. Aulton's Pharmaceutics - The Design and Manufacture of Medicines, Third Edition. Chapter 1, Page 8.) --Raspatarian 04:25, 27 January 2009 (UTC)

I have a further question about alternative routes of administration: Can strain on the liver from drugs with a big "first pass effect" problem be reduced through administration through mucous membranes, ie "snorting" or application to the vaginal wall (women) or urethra (men) if tablets are crushed to a fine powder. If so, are there any risks associated with doing so other than the obvious one, ie. overdose, which would outweigh the benefits? FWIW, the sort of circumstances I'm talking about is harm reduction in circumstances where a doctor prescribes a physically necessary medication with a high first pass effect and advises "you must now go easy on alcohol(/steroids/whatever non-prescribed drug the patient has incidentally disclosed using) because your liver will be under a lot of strain already with this medication" but the patient, for whatever reason, fails to do so.

In medschool we learn from the textbooks that suppositories have less FPE. —Preceding unsigned comment added by 90.185.143.213 (talk) 18:44, 13 January 2010 (UTC)[reply]

From my understanding, only the superior rectal vein drains into the inferior mesenteric vein. Whereas the other veins draining the rectum would bypass the portal circulation via the inferior vena cava. Thus, for the most part the drug would bypass the liver. (101.161.8.226 (talk) 11:15, 22 October 2017 (UTC))[reply]

Transdermal route[edit]

Also bypasses the FPE and goes into systemic circulation. Eg. oxybutinin patches, where conventional tablets cause significantly more adverse effects than the patches do. — Preceding unsigned comment added by 220.239.41.11 (talk) 14:36, 4 May 2013 (UTC)[reply]