Document Detail

Pharmacodynamics of the hypotensive effect of levodopa in parkinsonian patients.
MedLine Citation:
PMID:  1423336     Owner:  NLM     Status:  MEDLINE    
Blood pressure effects of i.v. levodopa were examined in parkinsonian patients with stable and fluctuating responses to levodopa. The magnitude of the hypotensive effect of levodopa was concentration dependent and was fit to an Emax model in fluctuating responders. Stable responders demonstrated a small hypotensive response. Baseline blood pressures were higher in fluctuating patients; a higher baseline blood pressure correlated with greater hypotensive effects. Antiparkinsonian effects of levodopa temporally correlated with blood pressure changes. Phenylalanine, a large neutral amino acid (LNAA) competing with levodopa for transport across the blood-brain barrier, reduced the hypotensive and antiparkinsonian effects of levodopa. We conclude that levodopa has a central hypotensive action that parallels the motor effects in fluctuating patients. The hypotensive effect appears to be related to the higher baseline blood pressure we observed in fluctuating patients relative to stable patients.
R P Irwin; J G Nutt; W R Woodward; S T Gancher
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Publication Detail:
Type:  Clinical Trial; Journal Article; Randomized Controlled Trial; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Clinical neuropharmacology     Volume:  15     ISSN:  0362-5664     ISO Abbreviation:  Clin Neuropharmacol     Publication Date:  1992 Oct 
Date Detail:
Created Date:  1992-12-15     Completed Date:  1992-12-15     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  7607910     Medline TA:  Clin Neuropharmacol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  365-74     Citation Subset:  IM    
Department of Neurology, Oregon Health Sciences University, Portland.
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MeSH Terms
Amino Acids / pharmacology
Blood Pressure / drug effects
Brain / metabolism
Dose-Response Relationship, Drug
Double-Blind Method
Hypotension / chemically induced*
Infusions, Intravenous
Levodopa / adverse effects,  pharmacokinetics,  pharmacology*
Locomotion / drug effects
Middle Aged
Motor Activity / drug effects
Parkinson Disease / drug therapy,  metabolism,  physiopathology*
Phenylalanine / pharmacology
Grant Support
Reg. No./Substance:
0/Amino Acids; 0/Levodopa; 63-91-2/Phenylalanine

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