Droxidopa(L-DOPS), the mixture of Droxidopa (w/w80%) and Pharmaceutical starch (w/w20%), acts as a prodrug to the neurotransmitters norepinephrine (noradrenaline) and epinephrine (adrenaline); Droxidopa(L-DOPS) is capable of crossing the protective blood–brain barrier[1][2].
The acute administration of droxidopa in PVL and BDL rats caused a significant and maintained increase in arterial pressure and mesenteric arterial resistance, with a significant decrease of mesenteric arterial and portal blood flow, without changing portal pressure and renal blood flow[1]. Droxidopa(L-DOPS) is a pro-drug which has a structure similar to noradrenaline, but with a carboxyl group. It has no pressor effects in this form. It can be administered orally, unlike noradrenaline, and after absorption is converted by the enzyme dopa decarboxylase into noradrenaline thus increasing levels of the neurotransmitter which is identical to endogenous noradrenaline[2].
References:
[1]. Coll M, et al. Droxidopa, an oral norepinephrine precursor, improves hemodynamic and renal alterations of portal hypertensive rats. Hepatology. 2012 Nov;56(5):1849-60.
[2]. Mathias CJ. L-dihydroxyphenylserine (Droxidopa) in the treatment of orthostatic hypotension: the European experience. Clin Auton Res. 2008 Mar;18 Suppl 1:25-9.