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(trip-tuh-fan) ,


(trade name)


Therapeutic: mood stabilizers
Premenstrual dysphoric disorder (PMDD)Depression.Smoking cessation.Insomnia.


L-tryptophan is an essential amino acid that is converted by the body to 5–hydroxytryptophan (5–HTP) and then to serotonin. Both L-tryptophan and 5–HTP cross the blood-brain barrier and have sedative effects. Depletion of endogenous tryptophan can cause a relapse in depression symptoms.

Therapeutic effects

Improved symptoms of depression.
Improved sleep.


Absorption: Unknown
Distribution: Unknown
Metabolism and Excretion: Unknown
Half-life: Unknown

Time/action profile



Contraindicated in: Hypersensitivity.Pregnancy and lactation.
Use Cautiously in: Eosinophilia.Kidney disease.Liver disease.

Adverse Reactions/Side Effects

Central nervous system

  • ataxia
  • headache
  • drowsiness
  • lightheadedness

Ear, Eye, Nose, Throat

  • visual blurring


  • heartburn
  • abdominal pain
  • dry mouth
  • nausea


  • eosinophilia-myalgia syndrome


Increased risk of serotonergic effects and serotonin syndrome with SSRIs,dextromethorphan,meperidine,tricyclic antidepressantsmonoamine oxidase inhibitorspentazocine andtramadol. Increased sedation with CNS depressants. Additive sedation with herbs or supplements that have sedative properties such as kavaSt. John's wortvalerian5–HTPand others.Increased risk of serotonin syndrome with St. John's wort.
Oral (Adults) Insomnia—1 gram 20 minutes before bedtime; Depression—300 mg/day; Prementrual syndrome—6 grams/day; Smoking cessation—50 mg/kg/day.


Capsules: Tablets: 500 mg

Nursing implications

Nursing assessment

  • Assess sleep patterns prior to and periodically during therapy.
  • Monitor for signs and symptoms of esosinophilia-myalgia sydrome (severe myalgia, arthralgia, intense eosinophilia) Less common symptoms include respiratory prodrome (cough, dyspnea, pulmonary infiltrates), limb edema, scleroderma, mononeuritis, evanescent skin rash, mild LFT elevations, and leukocytosis. If these symptoms occur, discontinue l-tryptophan.

Potential Nursing Diagnoses

Deficient knowledge, related to medication regimen (Patient/Family Teaching)


  • Oral: Administer without regard to food.

Patient/Family Teaching

  • Instruct patient to take as directed; do not take more than directed.
  • Advise patient to notify health care professional of symptoms of esosinophilia-myalgia sydrome occur.
  • Advise female patient to notify health care professional if pregnancy is planned or suspected or if breastfeeding.

Evaluation/Desired Outcomes

  • Improvement in insomnia and premenstrual disorder.


The biologically active form of the amino acid tryptophan. It is sold as a dietary supplement for use as a sleep aid and mood enhancer.
References in periodicals archive ?
group, there were no associated changes between externally added L-tryptophan and ammonia, [H.
No doubt by now you've seen the article on L-Tryptophan in our July issue ("Talking Turkey"), which indicated that in double-blind studies (and one single-blind study), the supplement didn't prove to be as helpful for anxiety-related disorders as some hoped it would.
Chronic increase of dietary L-tryptophan decreases gentle feather pecking behaviour.
In this study, the effect of 2-pyridinecarboxylic acid (picolinic acid), a catabolite of L-tryptophan, was tested against trypanosomes of the subgenus Schizotrypanum isolated from the bat Phyllostomus hastatus.
Ephedra was banned in the US due to its serious side effects including psychiatric symptoms, palpitation, stomach upset and death, while the use of l-tryptophan has been associated with eosinophilic myalgia syndrome (EMS), a potentially fatal muscle disorder responsible for at least 38 deaths worldwide.
Each sphere was then covered with a thin, ethyl cellulose film, incorporating a channelizer and a plasticizer whose formula precisely regulated L-tryptophan release rate (24-27).
Ajinomoto Heartland LLC produces L-Lysine, L-Threonine, L-Tryptophan and L-Valine.
United States regulatory agencies have recently reversed a 20-year ban on the over-the-counter sale of the essential amino acid L-tryptophan, and will once again allow it to be sold as a dietary supplement.
Serotonin (5'-hydroxy tryptamine; 5-HT) is a bioamine, which is synthesized from L-tryptophan mainly in enterochromaffin cells of the gastrointestinal tract and central nervous system.
The most frequently amino acids used in callus culture are glycine, asparagine, L-glutamine, L-proline and L-tryptophan (Kopertekh and Stribnaya, 2003; Saharan et al.