Failure of vitamin B6 to reverse the L-dopa effect in patients on a dopa decarboxylase inhibitor.

Niacin depletion in Parkinsonian patients treated with L-dopa, benserazide and carbidopa.

1. Benserazide and carbidopa, decarboxylase inhibitors used in the treatment of Parkinson's disease, have been shown to inhibit the enzyme kynurenine hydrolase in rat and mouse liver. This results in reduced synthesis of nicotinamide coenzymes from tryptophan, and hence an increased reliance on dietary niacin. 2. Pellagra might be expected as a result of this inhibition of endogenous synthesis ...

The Effect of Oral Administration of L-Tyrosine, Folic acid and Pyridoxine on Perphenazine Induced Catatonia in Rat

L-tyrosine, B6 and folic acid are involved in biosynthesis of DOPA and consequently dopamine. The aim of this study was to investigate the antiparkinsonian effect of these agents in perphenazine-induced catatonia in rats. Murprogo method or scored muscular rigidity, which is induced by a phenothiazine, was used to evaluate the antiparkinsonian effect of these agents. A significant decrease in m...

Advances in Neurology, Volume 2. Treatment of Parkinsonism—The Role of Dopa Decarboxylase Inhibitors

This is an excellent compendium of current information on the status of various Dopa decarboxylase inhibitors in clinical practice. The book contains excellent articles on the experimental pharmacology of these inhibitors as well. This information is of importance because inhibitors of Dopa decarboxylase promise to play an important role in the treatment of Parkinson's disease. L-Dopa, as is ge...

Peripheral aromatic L-amino acids decarboxylase inhibitor in parkinsonism. II. Effect on metabolism of L-2- 14 C-dopa.

Modification of the cardiovascular effects of L-dopa by decarboxylase inhibitors.

Intravenously infused L-dopa (0.3 mg/kg per min) produced hypertension and cardiac arrhythmias in halothane anesthetized dogs. Biochemical studies showed that the heart, kidney, and brain of these animals accumulated significant amounts of catecholamines formed from the administered precursor. Pretreatment of dogs with an extracerebral inhibitor of dopa decarboxylase [D,L-alpha-hydrazino-alpha-...