First-dose phenomenon

<h2 id="other-drug-classes-with-observed-first-dose-hypotension">Other drug classes with observed first dose hypotension</h2>
<p>This effect is also observed after the administration of the first dose of drugs in the ACEi class (<a href="/facts/Angiotensin-converting_enzyme_inhibitor/cHT1Yxub">angiotensin-converting enzyme inhibitor</a>).<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> This may occur with the class's better known side effect of dry cough (due to decreased breakdown of bradykinin), though there is no clear relationship between the two side effects.
</p><p>The first dose phenomenon in ACEi is reduced and made safer by avoiding diuretics for 24 hours prior to first dose, taking first dose at night (so avoiding falls, etc) and starting on low doses and titrating upwards.
</p>
<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/First_pass_effect/jfDsbq7S">First pass effect</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Graham RM, Thornell IR, Gain JM, Bagnoli C, Oates HF, Stokes GS (1976). "Prazosin: the first-dose phenomenon". British Medical Journal. 2 (6047): 1293–4. doi:10.1136/bmj.2.6047.1293. PMC 1689975. PMID 793676. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1689975" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1689975</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>"Hytrin (Terazosin Hcl) drug warnings and precautions – prescription drugs and medications at RxList". Archived from the original on 2008-06-16. Retrieved 2007-10-20. <a href="https://web.archive.org/web/20080616122234/http://www.rxlist.com/cgi/generic/teraz_wcp.htm" target="_blank">https://web.archive.org/web/20080616122234/http://www.rxlist.com/cgi/generic/teraz_wcp.htm</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>"Minipress (Prazosin HCl) drug warnings and precautions – prescription drugs and medications at RxList". Archived from the original on 2007-11-02. Retrieved 2007-10-20. <a href="https://web.archive.org/web/20071102081514/http://www.rxlist.com/cgi/generic/prazosin_wcp.htm#W" target="_blank">https://web.archive.org/web/20071102081514/http://www.rxlist.com/cgi/generic/prazosin_wcp.htm#W</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>Elliott HL, McLean K, Sumner DJ, Meredith PA, Reid JL (1981). "Immediate cardiovascular responses to oral prazosin—effects of concurrent beta-blockers". Clinical Pharmacology and Therapeutics. 29 (3): 303–9. doi:10.1038/clpt.1981.40. PMID 6110503. S2CID 3085281. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>"Digital Medicines Information Suite". <a href="http://www.medicinescomplete.com/mc/bnf/current/PHP1124-angiotensin-converting-enzyme-inhibitors.htm" target="_blank">http://www.medicinescomplete.com/mc/bnf/current/PHP1124-angiotensin-converting-enzyme-inhibitors.htm</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
</ol>

First-dose phenomenon open-in-new

First-dose phenomenon