Long COVID Patterns in the RECOVER-Adult Study
November 21, 2025
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Brand Name :
Stimol
Synonyms :
citrulline
Class :
Nutritional supplement
Brand Name :
Stimol
Synonyms :
citrulline
Class :
Nutritional supplement
Dosage Forms & StrengthsÂ
Oral powderÂ
1.5 gramsÂ
Exercise Performance EnhancementÂ
Indicated for athlete performance enhancement
1.5 to 5 grams is taken orally daily for four months
Not indicatedÂ
Refer to the adult dosing Â
may have a decrease in excretion when combined with cephalexin
may have a decrease in excretion when combined with chlorothiazide
may have a decrease in excretion when combined with cimetidin
may have a decrease in excretion when combined with enalapril
may have a decrease in excretion when combined with esomeprazole
may have a decrease in excretion when combined with cefadroxil
may have a decrease in excretion when combined with acetylsalicylic acid
may have a decrease in excretion when combined with acetazolamide
may have a decrease in excretion when combined with acyclovir
may have a decrease in excretion when combined with aminohippuric acid
may have a decrease in excretion when combined with aminophenazone
may have a decrease in excretion when combined with amoxicillin
may have a decrease in excretion when combined with antipyrine
may have a decrease in excretion when combined with apalutamide
may have a decrease in excretion when combined with ataluren
may have a decrease in excretion when combined with avatrombopag
may have a decrease in excretion when combined with benzylpenicillin
may have a decrease in excretion when combined with cabotegravir
may have a decrease in excretion when combined with cefaclor
may have a decrease in excretion when combined with ceftizoxime
may have a decrease in excretion when combined with ceftriaxone
may have a decrease in excretion when combined with chloramphenicol
may have a decrease in excretion when combined with chlorpropamide
may have a decrease in excretion when combined with cinoxacin
may have a decrease in excretion when combined with codeine
may have a decrease in excretion when combined with cyclosporine
may have a decrease in excretion when combined with cyclothiazide
may have a decrease in excretion when combined with dabrafenib
may have a decrease in excretion when combined with diclofenac
may have a decrease in excretion when combined with diflunisal
may have a decrease in excretion when combined with dolutegravir
may have a decrease in excretion when combined with dinoprostone
may have a decrease in excretion when combined with dronedarone
may have a decrease in excretion when combined with enasidenib
may have a decrease in excretion when combined with encorafenib
may have a decrease in excretion when combined with etodolac
may have a decrease in excretion when combined with famotidine
may have a decrease in excretion when combined with fexinidazole
may have a decrease in excretion when combined with flurbiprofen
may have a decrease in excretion when combined with furosemide
may have a decrease in excretion when combined with gentamicin
may have a decrease in excretion when combined with guanidine
may have a decrease in excretion when combined with indomethacin
may have a decrease in excretion when combined with leucovorin
may have a decrease in excretion when combined with linezolid
may have a decrease in excretion when combined with losartan
may have a decrease in excretion when combined with meclofenamic acid
may have a decrease in excretion when combined with melatonin
may have a decrease in excretion when combined with mercaptopurine
may have a decrease in excretion when combined with methotrexate
may have a decrease in excretion when combined with minocycline
may have a decrease in excretion when combined with nafcillin
may have a decrease in excretion when combined with naproxen
may have a decrease in excretion when combined with norfloxacin
may have a decrease in excretion when combined with ofloxacin
may have a decrease in excretion when combined with ouabain
may have a decrease in excretion when combined with oxyphenbutazone
may have a decrease in excretion when combined with pantoprazole
may have a decrease in excretion when combined with phenylbutazone
may have a decrease in excretion when combined with piperacillin
may have a decrease in excretion when combined with piroxicam
may have a decrease in excretion when combined with pravastatin
may have a decrease in excretion when combined with probenecid
may have a decrease in excretion when combined with quinidine
may have a decrease in excretion when combined with ranitidine
may have a decrease in excretion when combined with rifampicin
may have a decrease in excretion when combined with tenoxicam
may have a decrease in excretion when combined with teriflunomide
may have a decrease in excretion when combined with tetracycline
may have a decrease in excretion when combined with tolbutamide
may have a decrease in excretion when combined with tolmetin
may have a decrease in excretion when combined with trifluridine
may have a decrease in excretion when combined with valproic acid
may have a decrease in excretion when combined with zidovudin
Actions and spectrum:Â
Action:Â
Arginine Precursor: Citrulline is converted into arginine in kidneys. Arginine, in turn, serves as a precursor for the synthesis of nitric oxide. Nitric oxide helps to relax blood vessels, promoting improved blood flow.Â
Nitric Oxide Production: The increase in arginine levels resulting from citrulline supplementation can contribute to enhanced nitric oxide production. Nitric oxide is important for maintaining vascular tone and supporting cardiovascular health.Â
Exercise Performance: Supplementing with citrulline has been investigated for its ability to lessen soreness in the muscles and enhance performance during exercise, especially during high-intensity anaerobic activities. The improved blood flow and potential reduction in ammonia levels contribute to these effects.Â
Frequency not definedÂ
Heart burnÂ
Stomach upsetÂ
Black Box Warning:Â
None
Contraindication/Caution:Â
Contraindication:Â
Allergies or Sensitivities: Individuals with known allergic or sensitivities to citrulline or related compounds should avoid citrulline supplementation.Â
Kidney Disorders: Citrulline is involved in the urea cycle, which plays a role in ammonia detoxification. Individuals with pre-existing kidney disorders should exercise caution and consult healthcare professionals before using citrulline supplements.Â
Hereditary Urea Cycle Disorders: Individuals with hereditary urea cycle disorders, rare genetic conditions that affect the body’s ability to eliminate ammonia, should avoid citrulline supplementation. These individuals typically have difficulties with the urea cycle, and citrulline may exacerbate their condition. Â
Medication Interactions: Citrulline may interact with certain medications, particularly those that affect blood pressure or medications used for erectile dysfunction. Individuals taking medications should consult with healthcare professionals before using citrulline supplements to avoid potential interactions.Â
Pregnancy and Breastfeeding: Information on the safety of citrulline supplementation during pregnancy and breastfeeding is limited. Pregnant and breastfeeding individuals should consult with healthcare professionals before using citrulline supplements.Â
Pregnancy consideration:Â Â
Pregnancy category: N/AÂ Â Â
Lactation: excreted into human milk is unknownÂ
Pregnancy categories:Â
Category A: well-controlled and Satisfactory studies show no risk to the fetus in the first or later trimester.Â
Category B: there was no evidence of risk to the fetus in animal studies, and there were not enough studies on pregnant women.Â
Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.  Â
Category D: adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.Â
Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.Â
Category N: There is no data available for the drug under this category.Â
Pharmacology:Â
Citrulline is a non-essential amino acid with notable roles in the body’s biochemical processes. Its primary pharmacological action involves serving as a precursor to arginine, a semi-essential amino acid. Within the urea cycle, citrulline is converted into arginine, which, in turn, is utilized for the synthesis of nitric oxide . Nitric oxide is a signalling molecule with vasodilatory effects, contributing to the relaxation of blood vessels and improved blood flow. Â
Pharmacodynamics:Â
Urea Cycle Involvement: Citrulline is a crucial intermediate in the urea cycle that occurs in the liver and kidneys. The process of ammonia detoxification involves the urea cycle, a waste product generated during the breakdown of proteins.Â
Conversion to Arginine: Within the urea cycle, citrulline is converted into arginine through the action of enzymes such as argininosuccinate synthase. An important amino acid that is needed to produce nitric oxide is arginine.Â
Nitric Oxide Synthesis: Arginine, derived from citrulline, is a substrate for nitric oxide synthase. Nitric oxide is a signaling molecule with vasodilatory effects, influencing blood vessel dilation, and regulating blood flow. Â
Pharmacokinetics:Â
Absorption: Citrulline is absorbed in the small intestine, mainly through active transport mechanisms. It can also be absorbed in the colon to a lesser extent.Â
Distribution: Once absorbed, citrulline is distributed through the bloodstream to various tissues. It is mainly concentrated in the kidneys, where a significant portion is converted into arginine.Â
Metabolism: The primary metabolic fate of citrulline is its conversion into arginine. This conversion occurs in the kidneys through the action of the enzyme argininosuccinate synthase. Arginine, in turn, serves as a precursor for the synthesis of nitric oxide.Â
Excretion and Elimination: Citrulline itself is not excreted in significant amounts. Instead, its metabolite, arginine, and the by-products of the urea cycle, including ornithine and urea, are excreted. The urea cycle is crucial for detoxifying ammonia, and citrulline’s involvement in this process contributes to the elimination of nitrogen waste.Â
Administration:Â
Dosage: The recommended dosage of citrulline can vary, and individual responses may differ. Â
Timing: Citrulline supplements are often taken before exercise or at other times during the day, depending on the individual’s goals. For exercise performance, some individuals take citrulline as part of a pre-workout regimen.Â
Formulations: Citrulline is available in various formulations, including citrulline malate. Citrulline malate combines citrulline with malic acid and is a common form used in supplements.Â
Patient information leafletÂ
Generic Name: citrullineÂ
Why do we use citrulline?Â
Citrulline is utilized for various purposes, primarily as a dietary supplement known for its potential health and performance benefits. One of its key roles is as a precursor to arginine, contributing to increased nitric oxide production, which may enhance blood vessel dilation and improve blood flow.
This cardiovascular effect has implications for exercise performance, and athletes and fitness enthusiasts often explore citrulline supplementation to support endurance and reduce muscle fatigue.Â
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