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Pharmacokinetic and pharmacodynamic properties of oral L-citrulline and L-arginine: impact on nitric oxide metabolism

Edzard Schwedhelm, Renke Maas, Ralf Freese, Donald Jung, Zoltan Lukacs, Alen Jambrecina, William Spickler, Friedrich Schulze, Rainer H Böger
British Journal of Clinical Pharmacology 2008 65(1):51–59

Bibliography

PubMed
PMID 17662090
PubMed Central
PMC2291275
Funding
Not yet independently verified in full text
Competing interests
Not yet independently verified in full text

Study snapshot

DesignDouble-blind randomized placebo-controlled crossover pharmacokinetic study
ModelHealthy adult volunteers
Sample20 healthy volunteers
InterventionSeveral one-week dosing schedules of oral L-citrulline, sustained-release L-arginine and immediate-release L-arginine
DurationOne week per schedule
EndpointsPlasma L-arginine exposure; Plasma L-citrulline exposure; Nitrate excretion; Urinary cGMP; Flow-mediated dilation

What the study showed, in plain terms

Oral citrulline raised plasma L-arginine exposure efficiently and, at higher doses, raised some nitric oxide-related biomarkers. Pharmacokinetic superiority is not proof of improved patient outcomes.

Key findings

L-citrulline increased arginine AUC and peak concentration dose-dependently. At the highest studied schedule, urinary nitrate and cGMP increased.

What this study can and cannot tell us

Small healthy-volunteer study, surrogate outcomes, non-equivalent dosing comparisons. Does not prove clinical superiority in hypertension or erectile dysfunction.

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