Pharmacokinetics
Absorption
Doxepin is well-absorbed from the gastrointestinal tract but between 55 and 87% undergoes first-pass metabolism in the liver, resulting in a mean oral bioavailability of approximately 29%. Following a single very low dose of 6 mg, peak plasma levels of doxepin are 0.854 ng/mL (3.06 nmol/L) at 3 hours without food and 0.951 ng/mL (3.40 nmol/L) at 6 hours with food. Plasma concentrations of doxepin with antidepressant doses are far greater, ranging between 50 and 250 ng/mL (180 to 900 nmol/L). Area-under-curve levels of the drug are increased significantly when it is taken with food. Distribution
Doxepin is widely distributed throughout the body and is approximately 80% plasma protein-bound, specifically to albumin and α1-acid glycoprotein. Metabolism
Doxepin is extensively metabolized by the liver via oxidation and N-demethylation. Its metabolism is highly stereoselective. Based on in vitro research, the major enzymes involved in the metabolism of doxepin are the cytochrome P450 enzymes CYP2D6 and CYP2C19, with CYP1A2, CYP2C9, and CYP3A4 also involved to a lesser extent. The major active metabolite of doxepin, nordoxepin, is formed mainly by CYP2C19 (>50% contribution), while CYP1A2 and CYP2C9 are involved to a lesser extent, and CYP2D6 and CYP3A4 are not involved. Both doxepin and nordoxepin are hydroxylated mainly by CYP2D6, and both doxepin and nordoxepin are also transformed into glucuronide conjugates. The elimination half-life of doxepin is about 15–18 hours, whereas that of nordoxepin is around 28–31 hours.
Nervous may refer to:

nervousness
Nervous system, a network of cells in an animals body that coordinates movement and the senses
Nervous tissue, the cells of the nervous system that work in aggregate to transmit signals

Music
"Nervous" (Gene Summers song), 1958; covered by several performers
"Nervous" (Gavin James song), 2016
"Nervous" (Shawn Mendes song), 2018
"Nervous", a song by K.Flay from Solutions, 2019
"Nervous", a song by L Devine, 2018
"Nervous", a song by Nick Jonas from Spaceman, 2021
Nervous Records, a UK record label
Nervous Records (US), a US record label

See also
"Nervousness", a song by the Gigolo Aunts from Tales from the Vinegar Side
Nervous Norvus (1912–1968), the performing name of Jimmy Drake
Nervous shark, a species of requiem shark
All pages with titles beginning with Nervous