PMID: 1355542Apr 1, 1992Paper

Decarboxylation of L-dopa in the rat isolated vascularly perfused small intestine: contribution to systemic elimination and dose-dependent first pass effect

The Journal of Pharmacy and Pharmacology
M H de VriesJ Noordhoek


The contribution of the rat small intestine to systemic and presystemic elimination of L-dopa was studied. When L-dopa was administered into the vascular perfusate, a systemic extraction ratio of 0.38 was found, the major part being decarboxylated to dopamine. The intestinal L-dopa clearance was estimated to be 17.1 mL min-1 kg-1. Thus, L-dopa intestinal clearance in rat represents up to at least 20% of the total body clearance. After luminal administration of L-dopa 83-88% of the administered dose was absorbed within 60 min. The total amount of L-dopa appearing in the vascular perfusate increased more than proportionally to the increase in the dose. In contrast, the amount of dopamine increased less than proportionally to the dose. As a result, the intestinal first pass appeared to be strongly dose-dependent. Since the total percentage absorbed from the lumen was independent of the administered dose and the total amount that appeared in the vascular perfusate increased linearly with the dose, the dose dependency was probably due to saturation of intestinal L-dopa decarboxylation.


Apr 1, 1976·Xenobiotica; the Fate of Foreign Compounds in Biological Systems·L K Cheng, H L Fung
Jun 15, 1975·Biochemical Pharmacology·L LandsbergP Silva
Jun 1, 1987·The Journal of Pharmacy and Pharmacology·K IwamotoT Matsushita
Jan 1, 1987·Archives of Toxicology·M Schwenk
Apr 13, 1973·Nature·D N WadeJ L Morris
Nov 15, 1973·Biochemical Pharmacology·L Landsberg, H L Taubin
Jul 1, 1981·Clinical Pharmacokinetics·C F George

❮ Previous
Next ❯


Jan 1, 1993·Fundamental & Clinical Pharmacology·M A Vieira-Coelho, P Soares-da-Silva

❮ Previous
Next ❯

Related Concepts

Trending Feeds


Coronaviruses encompass a large family of viruses that cause the common cold as well as more serious diseases, such as the ongoing outbreak of coronavirus disease 2019 (COVID-19; formally known as 2019-nCoV). Coronaviruses can spread from animals to humans; symptoms include fever, cough, shortness of breath, and breathing difficulties; in more severe cases, infection can lead to death. This feed covers recent research on COVID-19.

Hereditary Sensory Autonomic Neuropathy

Hereditary Sensory Autonomic Neuropathies are a group of inherited neurodegenerative disorders characterized clinically by loss of sensation and autonomic dysfunction. Here is the latest research on these neuropathies.

Evolution of Pluripotency

Pluripotency refers to the ability of a cell to develop into three primary germ cell layers of the embryo. This feed focuses on the mechanisms that underlie the evolution of pluripotency. Here is the latest research.

Chronic Fatigue Syndrome

Chronic fatigue syndrome is a disease characterized by unexplained disabling fatigue; the pathology of which is incompletely understood. Discover the latest research on chronic fatigue syndrome here.

Nuclear Pore Complex in ALS/FTD

Alterations in nucleocytoplasmic transport, controlled by the nuclear pore complex, may be involved in the pathomechanism underlying multiple neurodegenerative diseases including Amyotrophic Lateral Sclerosis and Frontotemporal Dementia. Here is the latest research on the nuclear pore complex in ALS and FTD.

Landau-Kleffner Syndrome

Landau Kleffner syndrome (LKS), also called infantile acquired aphasia, acquired epileptic aphasia, or aphasia with convulsive disorder, is a rare childhood neurological syndrome characterized by the sudden or gradual development of aphasia (the inability to understand or express language) and an abnormal electroencephalogram. Discover the latest research on LKS here.

STING Receptor Agonists

Stimulator of IFN genes (STING) are a group of transmembrane proteins that are involved in the induction of type I interferon that is important in the innate immune response. The stimulation of STING has been an active area of research in the treatment of cancer and infectious diseases. Here is the latest research on STING receptor agonists.


Microbicides are products that can be applied to vaginal or rectal mucosal surfaces with the goal of preventing, or at least significantly reducing, the transmission of sexually transmitted infections. Here is the latest research on microbicides.

Regulation of Vocal-Motor Plasticity

Dopaminergic projections to the basal ganglia and nucleus accumbens shape the learning and plasticity of motivated behaviors across species including the regulation of vocal-motor plasticity and performance in songbirds. Discover the latest research on the regulation of vocal-motor plasticity here.