русский

Known interactions

Acanthopanax senticosus, Achillea, Achillea millefolium, Ademetionine, African Pepper, Ague Tree, Alant, AllerMax, Alprazolam Intensol, Alprazolam Oral Solution, Alprazolam tablets, Amber Touch-and-Heal, Ambien, Amobarbital, Amytal, Anthemis nobilis, Antispasmodic Elixer, Apricot Vine, Aquatab C Tablets, Aquatab DM, Ativan, Ativan Injection, Atropine, Hyoscyamine, Phenobarbital, and Scopolamine Oral, Atropine, Hyoscyamine, Phenobarbital, and Scopolamine Elixir, Awa, Baikal Scullcap, Baikal Skullcap Root, Baldarian, Balm Mint, Banophen, Banophen Allergy Elixir, Bellacane SR, Belladonna Alkaloids, Ergotamine, and Phenobarbital Tablets, Bellaspas, Bellergal-S, Benadryl, Benadryl Injection, Benadryl Liquid, Benadryl Topical, Benylin, Benylin Expectorant Liquid, Bird Pepper, Bloodwort, Bramhi, Butabarbital, Butabarbital Oral Elixir, Butisol, Butisol Elixir, Calendula, Calendula officinalis, Capsicum, Capsicum annuum, Capsicum frutescens, Carbex, Catmint, Catnep, Catnip, Catrup, Catswort, Celexa, Celexa Solution, Centella asiatica, Chamomile, Cheracol D Cough Liquid, Children's Formula Cough Syrup, Chili Pepper, Chlordiazepoxide, Chlordiazepoxide and Clidinium Bromide, Chlordiazepoxide Injection, Chlorpromazine, Chlorpromazine Concentrate or Syrup, Chlorpromazine Extended-Release Capsules, Chlorpromazine Injection, Chlorpromazine Intensol Concentrate, Chlorpromazine Suppositories, Ci Wu Jia, Cinnamon Wood, Citalopram, Citalopram Oral Solution, Citalopram orally-disintegrating tablets, Clear Tussin 30 Liquid, Clonazepam, Clonazepam Orally Disintegrating Tablets, Clorazepate, Cold & Cough Tussin Softgels, Compazine, Compazine Injection, Compazine Rectal Suppositories, Compazine Spansules, Compazine Syrup, Corona de Cristo, citalopram orally-disintegrating tablets, Dalmane, Dehydroepiandrosterone, Delsym, Demerol Injection, Demerol Oral, Demerol Syrup, Devil's Bush, Devil's Leaf, Dextromethorphan, Dextromethorphan, Guaifenesin, and Potassium Guaiacolsulfonate, DHEA, Diabetic Tussin DM Liquid, Diastat, Diazepam, Diazepam Injection, Diazepam Intensol, Diazepam Oral Solution, Diazepam Rectal Gel, Diphen AF Liquid, Diphenhist, Diphenhydramine Injection, Diphenhydramine Liquid, Diphenhydramine Oral, Diphenhydramine Topical, Donnatal, Donnatal Elixir, Doral, Doxylamine, Eldepryl, Elecampane, Eleuthero, Eleutherococcus senticosus, Elf Dock, Elfwort, Estazolam, Etrafon, Extra Action Cough Syrup, Eyebalm, Fenesin DM Tablets, Field Balm, Field Wort, Fluoxetine and Olanzapine, Fluoxetine capsules (Sarafem), Fluoxetine Oral Solution, Fluoxetine tablets or capsules, Fluphenazine, Fluphenazine Injection, Fluphenazine Oral Concentrate or Elixir, Flurazepam, Fluvoxamine, Folergot-DF, fluoxetine delayed-release capsules, Garden Heliotrope, Garden Marigold, Genahist, Genahist Liquid, Genatuss DM Syrup, Genuine chamomile, German Chamomile, GL701, Goat's Pod, Gold Bloom, Golden Marigold, Goldenseal, Gotu Kola, Granadilla, Green Arrow, Ground Raspberry, Guaifenesin and Dextromethorphan Oral Solution, Guaifenesin and Dextromethorphan, Guaifenex DM Tablets, Guiatuss CF Syrup, Guiatuss DM Syrup, Guiatussin with Dextromethorphan Liquid, Halcion, Halotussin DM Sugar Free Syrup, Halotussin DM Syrup, Hardhay, Holligold, Hops, Horse-elder, Horseheal, Houblon, Huang Qin, Humibid DM, Humibid DM Sprinkle Capsules, Humibid DM Tablets, Humulus lupulus, Hungarian chamomile, Hwanggum, Hydrocotyle asiatica, Hyosophen Elixer, Hypericum, Hypericum perforatum, Indian Pennywort, Inula helenium, Iobid DM Tablets, Isocarboxazid, Kava, Kava-Kava, Kawa, Kew, Klamath Weed, Klonopin, Klonopin Wafer, Kolephrin GG/DM Liquid, Lemon Balm, Leonurus cardiaca, Librax, Libritabs, Librium, Librium Injection, Lion's Ear, Lion's Tail, Lorazepam, Lorazepam Injection, Lorazepam Intensol, Lorazepam Oral Solution, Luminal Sodium, Lupulin, Luvox, Marplan, Marsh Penny, Marybud, Matricaria chamomilla, Maxifed DM Tablets, Maypop, MEL, Mebaral, Medent-DM Tablets, Melatonin, Melissa, Melissa officinalis, Mellaril, Mellaril Suspension, Mellaril-S, Meperidine and Promethazine Oral, Meperidine Hydrochloride Injection, Meperidine Oral, Meperidine Syrup, Mephobarbital, Meprozine, Meridia, Mesoridazine Injection, Mesoridazine Oral, Mesoridazine Oral Concentrate, Mexican Chillies, Midazolam Injection, Midazolam Syrup, Milfoil, Millepertuis, MLT, Motherwort, Muco-Fen-DMT Tablets, Mytussin DM Liquid, N-acetyl-5-methoxytryptamine, Naldecon Senior DX Liquid, Nardil, Nembutal Elixir, Nembutal Injection, Nembutal Oral, Nembutal Sodium, Nepeta cataria, Nettle, Nettle Tops, Niravam, Nosebleed Plant, Ogon, Orangeroot, Oxazepam, PanMist-DM Tablets, Panmist-DM Syrup, Paprika, Parnate, Paroxetine, Paroxetine Oral Suspension, Passiflora incarnata, Passion Flower, Passion Vine, Paxil, Paxil CR, Paxil Suspension, Pentobarbital Injection, Pentobarbital Elixir, Pentobarbital Oral, Pentobarbital Suppositories, Permitil, Permitil Oral Concentrate, Perphenazine and Amitriptyline, Perphenazine Injection, Perphenazine Oral, Perphenazine Oral Concentrate, Pertussin, Phanatuss DM Syrup, Phenadex Senior Liquid, Phenelzine, Phenerbel-S, Phenergan DM, Phenobarbital, Phenobarbital Elixir, Phenobarbital Injection, Piper methysticum, Pot Marigold, Prasterone, Prochlorperazine, Prochlorperazine ER, Prochlorperazine Injection, Prochlorperazine Oral Syrup, Prochlorperazine Rectal Suppositories, Profen Forte DM Tablets, Profen II DM Liquid, Profen II DM Tablets, Prolixin, Prolixin Decanoate, Prolixin Elixir, Prolixin Enanthate, Prolixin Injection, Prolixin Oral Concentrate, Prometh with Dextromethorphan, Promethazine and Dextromethorphan, Promethazine DM, ProSom, Protuss DM Tablets, Prozac, Prozac Oral Solution, Prozac Weekly, Pseudoephedrine, Guaifenesin and Dextromethorphan, Pseudoephedrine, Guaifenesin, Dextromethhorphan Liquid, Pseudovent DM, Pushkarmoola, Quazapam, Red Pepper, Respa-DM Tablets, Restoril, Rhinosyn-DMX Syrup, Robafen CF Syrup, Robafen DM Syrup, Robitussin CF Syrup, Robitussin Cough, Robitussin DM Syrup, Roman Chamomile, Roman Nettle, Rosin Rose, Russian Root, S-adenosyl methionine (SAM-e), S-adenosyl-L-methionine, SAM, Safe Tussin 30 Liquid, Saloop, Sammy, Sarafem, Sarisol No.2, Sassafras, Sassafras albidum, Sassafras officinale, Saxifras, Scabwort, Scot-Tussin Senior Clear Liquid, Scute, Scutellaria baicalensis, Secobarbital, Seconal, Selegiline, Serax, Serentil, Serentil Injection, Serentil Oral Concetrate, Sertraline, Sertraline Oral Solution, Shigoka, Siberian Ginseng, Sibutramine, Siladryl Elixir, Silexin, Siltussin DM Syrup, SJW, Solfoton, Sonata, Sonazine Concentrate, Sonazine Syrup, Spastrin, St. John's Wort, Staunch Weed, Stelazine, Stelazine Injection, Stinging Nettle, Sudal-DM, Sweet Balm, Symbyax, Tabasco Pepper, Taiga, Temazepam, Thioridazine Suspension, Thioridazine Tablets, Thor-Prom, Thorazine, Thorazine Concentrate, Thorazine Injection, Thorazine Spansule, Thorazine Suppositories, Thorazine Syrup, Thorny Pepperbush, Thousand-Leaf, Throw-wort, Tipton Weed, Tolu-Sed DM Syrup, Tonga, Touch-Me-Not, Touro CC Tablets, Touro DM, Tramadol, Tramadol and Acetaminophen, Tranxene, Tranxene T, Tranxene-SD, Tranylcypromine, Triavil, Triazolam, Trifluoperazine Injection, Trifluoperazine Oral Concentrate, Trifluoperazine Oral Tablets, Trilafon, Trilafon Concentrate, Trilafon Injection, Tuss-DM, Tusstat Syrup, Ultracet, Ultram, Unisom, Urtica species, Valerian, Valeriana officinalis, Valeriana sambucifolia, Valeriana wallichi, Valeriane, Valium, Valium Injection, Velvet Dock, Versed, Versed Syrup, Vicks 44E Liquid, Vicks Pediatric Forumula 44E Liquid, Water Lemon, Wild Pepper, Wild Sunflower, Wogon, Wound Wort, Xanax, Yagona, Yarrow, Yarroway, Yellow Starwort, Yellowroot, Z-Cof DM Syrup, Zaleplon, Zanzibar Pepper, Zoloft, Zoloft Oral Solution, Zolpidem, Food and alcohol.

Information about L-tryptophan

Scientific Name: Tryptophan

Other Names: L-tryptophan

Who is this for?

While the sale of tryptophan as a dietary supplement is not prohibited in the United States, the U.S. Food and Drug Administration (FDA) has issued a statement expressing strong concerns about the safety of its use. In 1989 and 1990, deaths and serious illnesses were attributed to the use of contaminated tryptophan. At that time, the FDA instituted a recall of supplemental tryptophan. Although the contamination is thought to have been limited to products made by only one manufacturer, the exact reasons for the contamination are unclear. Tryptophan may now be purchased as a dietary supplement, again. However, the use of supplemental tryptophan is not recommended.

The body uses tryptophan to produce melatonin, a hormone that regulates sleep; niacin (vitamin B3), which is essential for normal gastrointestinal and nerve processes; and serotonin, a neurotransmitter involved in controlling moods and appetite.

Tryptophan is well-known as an antidepressant, because it converts into serotonin in the body. Serotonin is a neurotransmitter that helps to moderate depression and related disorders such as premenstrual syndrome. Neurotransmitters are chemicals that carry messages from nerve cells to other cells. Unlike antidepressant drugs known as selective serotonin reuptake inhibitors (SSRIs) that only preserve the amounts of serotonin already in circulation, tryptophan actually changes into additional serotonin. By increasing the amount of serotonin in the blood, tryptophan may also increase serotonin’s antidepressant effects. Tryptophan is also involved in the body’s regulation of sleep. It has been shown in human clinical studies that low levels of tryptophan contribute to insomnia. Increasing tryptophan may help to normalize sleep patterns. However, higher than usual levels of tryptophan in the blood have been associated with conditions such as chronic fatigue syndrome. Whether the high tryptophan levels are a cause of the condition or a result from it are unclear. More studies are underway to better understand tryptophan’s role in both depression and sleep disorders.

In other research, studies of tryptophan’s effect on eating may show that raising tryptophan levels in the body may decrease appetite – especially for carbohydrates. While the exact reasons for this effect have not been identified, it is known that consuming carbohydrates increases serotonin levels, making carbohydrates among the most often over consumed “comfort foods”. In general, eating them makes most individuals feel less depressed due to the increased serotonin levels they produce. Substituting tryptophan for carbohydrate foods may also reduce depressed feelings. For similar reasons, tryptophan may also have a role in helping smokers to quit.

When should I be careful taking it?

In 1989 and 1990, taking tryptophan was associated with a severe condition known as eosinophilia-myalgia syndrome. Although the exact causes for the outbreak are still not completely known, it is believed that a unique manufacturing process used by one company either introduced contaminants or caused reactions that formed toxic substances within the tryptophan that was produced. Eosinophilia-myalgia syndrome involves increased production of eosinophils (one type of white blood cells). It has potentially disabling symptoms that include fever, muscle pain, rash, and swelling in the arms and legs. Over 35 deaths were attributed to the toxic tryptophan and about 1500 more individuals are thought to have been permanently disabled by it.

Beginning about 1990, the sale of tryptophan as a single agent was restricted for some years in the United States. Although it continued to be included in some combination amino acid products and some special formulas, those products were used only with strict supervision from a healthcare professional. Currently, although tryptophan is back on the U.S. market as a non-prescription dietary supplement, the quality of any tryptophan product cannot be guaranteed.

While taking tryptophan is not recommended for anyone, certain individuals should be especially careful to avoid it.

  • In animal studies, high doses of tryptophan are believed to have caused birth defects. Additionally, high levels of tryptophan may cause developing babies to have serious breathing problems before they are born. Therefore, pregnant women should never take supplemental tryptophan.
  • Tryptophan is known to pass into the breast milk of new mothers, but its possible effects in infants are not known. Therefore, tryptophan should also be avoided during breast-feeding.
  • Individuals who have kidney or liver conditions should not take supplemental tryptophan due to the possibility that it may worsen these conditions.
  • Tryptophan may cause sedation, which may result in sleepiness or mental confusion during the daytime. Individuals who choose to take it should be careful when driving or performing other tasks that require alertness.

What side effects should I watch for?

In the early 1990s, the FDA withdrew tryptophan from the U.S. market due to a rare but definite association with fatal or disabling eosinophilia-myalgia syndrome. This condition may cause symptoms that include fatigue, fever, muscle and joint pain, rash, and swelling in the face, arms, or legs. Some individuals may be more likely to experience problems, but who might be affected is impossible to determine before symptoms develop. The severity of the possible results is also unpredictable.

Less Severe Side Effects

Oral tryptophan has also been associated with less serious side effects that include:

  • Blurry vision
  • Daytime drowsiness
  • Dry mouth
  • Headaches
  • Muscle incoordination
  • Nausea

What interactions should I watch for?

Prescription Drugs

When tryptophan is used with prescription drugs that promote sleepiness, the effects of the drug may be exaggerated, resulting in sedation or mental impairment. Prescription drugs that can cause sleepiness include:

  • Anticonvulsants such as carbamazepine, phenytoin and valproic acid
  • Barbiturates such as phenobarbital
  • Benzodiazepines such as alprazolam and diazepam
  • Drugs for insomnia such as Ambien and Sonata
  • Tricyclic antidepressants such as amitriptyline, amoxapine, doxepin and nortriptyline

Because it may block the effects of the enzyme monoamine oxidase, tryptophan may possibly increase the effects and the risk of side effects — including dangerous rapid increases in blood pressure — from prescription drugs that also interfere with monoamine oxidase. These drugs, known as monoamine oxidase inhibitors or MAOIs, include:

  • isocarboxazid (Marplan)
  • phenelzine (Nardil)
  • tranylcypromine (Parnate)

If tryptophan is taken with prescription antidepressants such as fluoxetine (Prozac), paroxetine (Paxil), or Zoloft that belong to the class known as selective serotonin re-uptake inhibitors (SSRIs), serotonin levels may become excessive. Serotonin syndrome, a rare but potentially dangerous condition, may develop. Uncontrolled serotonin syndrome may result in coma, seizures, and death. Symptoms of serotonin syndrome include:

  • Confusion
  • Euphoria
  • Fever
  • Hallucinations
  • Inability to coordinate muscles
  • Restlessness
  • Shakiness
  • Vomiting

Certain drugs — including sibutramine (Meridia), which is used to treat obesity, and meperidine and tramadol (Ultram), which are usually given to reduce pain — may also raise serotonin levels in the body. If one of these drugs is used at the same time as tryptophan, the risk of serotonin syndrome may increase.

If tryptophan is taken with drugs in the benzodiazepine or phenothiazine classes, symptoms that resemble Parkinson's disease may result. Benzodiazepines such as alprazolam (Xanax) and diazepam (Valium) are usually used to treat anxiety. Phenothiazines such as chlorpromazine (Thorazine), prochlorperazine (Compazine), thioridazine (Mellaril), and trifluoperazine (Stelazine) may be used to treat mental disorders or vomiting. Parkinson's-like symptoms may include muscle stiffness, the inability to move quickly, and trembling.

Non-prescription Drugs

The sleep-producing effects of over-the-counter products containing diphenhydramine may be enhanced by taking tryptophan at the same time. Diphenhydramine is contained in many non-prescription sleeping pills as well as in some cough and cold products, therefore caution should be used when taking these medications with tryptophan because excessive drowsiness may result.

Dextromethorphan is an anti-coughing ingredient in many non-prescription cough and cold products such as Nyquil and Robitussin DM. Because it may have an increasing effect on serotonin levels, taking dextromethorphan with tryptophan may result in a higher risk of side effects.

Herbal Products

Tryptophan may cause excessive sedation if it is taken with potentially sedating herbs such as:

  • Catnip
  • Hops
  • Kava
  • St. John's Wort
  • Valerian

Potentially, if tryptophan is taken with another supplement or herbal, such as SAM-e or St John's wort, that also may increase serotonin levels, the risk of serotonin syndrome may increase.

Foods

No interactions between tryptophan and foods have been reported, but drinking alcohol at the same time as taking tryptophan may result in increased drowsiness.

Some interactions between herbal products and medications can be more severe than others. The best way for you to avoid harmful interactions is to tell your doctor and/or pharmacist what medications you are currently taking, including any over-the-counter products, vitamins, and herbals.

Should I take it?

Tryptophan is one of the essential amino acids needed by humans - primarily to make proteins. Essential amino acids are necessary for body functions, but the human body cannot make them. They must be obtained from the diet in foods such as dairy products, eggs, fish, meats, and nuts. Commercial amino acid supplements commonly are derived from bacteria or plants; both of which do make essential amino acids. Supplemental tryptophan is made from purified bacteria by-products.

Tryptophan was first identified early in 1901 in a protein from milk. Nearly 70 years later, it was discovered to be involved in regulating appetite, mood, and sleep. Subsequently, tryptophan supplements were promoted for treating a number of conditions including depression, insomnia, and obesity. It was also thought to improve exercise capability, a theory that has not been proved. In 1989, a company that tried to increase their production of tryptophan, used a type of genetically modified bacteria. Over the next few years, suspected contaminants in the resulting tryptophan product caused more than 35 deaths and about 1500 cases of disability among individuals who took the product. Due to the severity of the reactions and the uncertainty about their exact cause, the FDA required all manufacturers of tryptophan to withdraw their products from the U.S. market. The only exceptions are medically-necessary foods and formulas that are given only under the supervision of a health professional.

Dosage and Administration

Although tryptophan is included in certain special dietary products, such as intravenous feedings and infant formulas, that are given with medical supervision; the use of tryptophan as a dietary supplement cannot be recommended.

Summary

The use of tryptophan as a dietary supplement cannot be recommended due to the slight possibility it may cause eosinophilia-myalgia syndrome that may result in death or permanent disability.

Risks

Eosinophilia-myalgia syndrome, a potentially life-threatening condition, has been attributed to taking tryptophan supplements. While investigations into the exact reasons for this association were made, the U.S. FDA removed most tryptophan supplements from the market in this country.

Pregnant and breast-feeding women and individuals who have kidney or liver diseases should be especially careful to avoid taking tryptophan supplements.

Side Effects

Documented cases of eosinophilia-myalgia syndrome have been associated with taking tryptophan supplements. Symptoms of this possibly fatal condition include:

  • Fever
  • Muscle and joint pain
  • Rash
  • Swelling in the face, arms, or legs

Less serious side effects such as blurry vision, drowsiness, muscle incoordination, and nausea may also be caused by supplemental tryptophan.

Interactions

Because it promotes sleepiness, tryptophan may increase the sedation associated with certain prescription drugs, non-prescription drugs, herbals, dietary supplements, and alcohol. Taking tryptophan may increase the risk of a serious condition known as serotonin syndrome, if it is taken with SSRI antidepressants, sibutramine, the pain drugs meperidine or tramadol, dextromethorphan, or herbals such as SAM-e or St. John's wort. Tryptophan may increase the effect and side effects from MAOI antidepressants. If it is used with anti-anxiety drugs in the benzodiazepine class or anti-psychotic drugs in the phenothiazine class, tryptophan may cause shaking, muscle stiffness, and other symptoms that resemble Parkinson's disease.

References

Adachi J, Asano M, Ueno Y. Tetrahydro-beta-carboline-3-carboxylic acids and contaminants of L-tryptophan. Journal of Chromatography A. 2000;881(1-2):501-515.

Anon. Update: eosinophilia-myalgia syndrome associated with ingestion of l-tryptophan – United States, through August 24, 1990. Morbidity and Mortality Weekly Report. 1990;39(34):587-589.

Barbarich NC, McConaha CW, Halmi KA, et al. Use of nutritional supplements to increase the efficacy of fluoxetine in the treatment of anorexia nervosa. International Journal of Eating Disorders. 2004;35(1):10-15.

Barrett S. Notes on the tryptophan disaster. QuackWatch. December 22, 2001. Available at: http://www.quackwatch.org/01QuackeryRelatedTopics/DSH/trypto.html. Accessed December 8, 2003.

Belongia EA, Hedberg CW, Gleich GJ, et al. An investigation of the cause of the eosinophilia-myalgia syndrome associated with tryptophan use. New England Journal of Medicine. 1990; 323(6):357-365.

Bornstein RA, Baker GB, Carroll A, King G, Wong JT, Douglass AB. Plasma amino acids in attention deficit disorder. Psychiatry Research. 1990;33(3):301-306.

Bowen DJ, Spring B, Fox E. Tryptophan and high-carbohydrate diets as adjuncts to smoking cessation therapy. Journal of Behavioral Medicine. 1991;14(2):97-110.

Castell LM, Yamamoto T, Phoenix J, Newsholme EA. The role of tryptophan in fatigue in different conditions of stress. Advances in Experimental and Medical Biology. 1999;467:697-704.

Cauffield JS, Forbes HJ. Dietary supplements used in the treatment of depression, anxiety, and sleep disorders. Lippincotts Primary Care Practice. 1999;3(3):290-304.

Cavaliere H, Medeiros-Neto G. The anorectic effect of increasing doses of L-tryptophan in obese patients. Eating and Weight Disorders. 1997;2(4):211-215.

Comings DE. Serotonin and the biochemical genetics of alcoholism: lessons from studies of attention deficit hyperactivity disorder (ADHD) and Tourette syndrome. Alcohol and Alcoholism Supplement. 1993;2:237-241.

Comings DE. Blood serotonin and tryptophan in Tourette syndrome. American Journal of Medical Genetics. 1990;36(4):418-430.

Delgado PL, Price LH, Miller HL, et al. Serotonin and the neurobiology of depression. Effects of tryptophan depletion in drug-free depressed patients. Archives of General Psychiatry. 1994;51(11):865-874.

Devoe LD, Castillo RA, Searle NS, Searle JR. Maternal dietary substrates and human fetal biophysical activity. The effects of tryptophan and glucose on fetal breathing movements. American Journal of Obstetrics and Gynecology. 1986;155(1):135-139.

Dick K. Molecule of the Month. Tryptophan. Advanced Chemistry Development. June 2002. Available at: http://www.acdlabs.com/publish/tryptophan/index.html. Accessed December 8, 2003.

Etzel KR, Stockstill JW, Rugh JD, Fisher JG. Tryptophan supplementation for nocturnal bruxism: report of negative results. Journal of Craniomandibular Disorders. 1991;5(2):115-120.

Fukuwatari T, Morikawa Y, Sugimoto E, Shibata K. Effects of fatty liver induced by niacin-free diet with orotic acid on the metabolism of tryptophan to niacin in rats. Biosciences, Biotechnology and Biochemistry. 2002 ;66(6):1196-1204.

Ghadirian AM, Murphy BE, Gendron MJ. Efficacy of light versus tryptophan therapy in seasonal affective disorder. Journal of Affective Disorders. 1998;50(1):23-27.

Ghose K. l-Tryptophan in hyperactive child syndrome associated with epilepsy: a controlled study. Neuropsychobiology. 1983;10(2-3):111-114.

Hartmann E, Spinweber CL. Sleep induced by L-tryptophan. Effect of dosages within the normal dietary intake. Journal of Nervous and Mental Diseases. 1979;167(8):497-499.

Hatch DL, Goldman LR. Reduced severity of eosinophilia-myalgia syndrome associated with consumption of vitamin-containing supplements before illness. Archives of Internal Medicine. 1993;153(20):2368-2373.

Heine WE. The significance of tryptophan in infant nutrition. Advances in Experimental Medicine and Biology. 1999;467:705-710.

Hoshino Y, Ohno Y, Yamamoto T, Kaneko M, Kumashiro H. Plasma free tryptophan concentration in children with attention deficit disorder. Folia of Psychiatry and Neurology of Japan. 1985;39(4):531-535.

Hughes JR, Stead LF, Lancaster T. Antidepressants for smoking cessation. Cochrane Database Systematic Review. 2003;(2):CD000031.

Ivey M, Eichenhorn MS, Glasberg MR, Hyzy RC. Hypercapnic respiratory failure due to L-tryptophan-induced eosinophilic polymyositis. Chest. 1991;99(3):756-757.

Jellin JM, Gregory P, Batz F, Hitchens K, et al, eds. Pharmacist's Letter/Prescriber's Letter. Natural Medicines Comprehensive Database, 3rd Edition. Stockton CA: Therapeutic Research Facility, 2000.

Johnson SK, Wagner GC, Fischer H. Neurochemical and motor effects of high dose haloperidol treatment: exacerbation by tryptophan supplementation. Proceedings of the Society for Experimental Biology and Medicine. 1992;200(4):571-575.

Kamb ML, Murphy JJ, Jones JL, Caston JC, Nederlof K, Horney LF, Swygert LA, Falk H, Kilbourne EM. Eosinophilia-myalgia syndrome in L-tryptophan-exposed patients. Journal of the American Medical Association. 1992;267(1):77-82.

Klarskov K, Johnson KL, Benson LM, Gleich GJ, Naylor S. Eosinophilia-myalgia syndrome case-associated contaminants in commercially available 5-hydroxytryptophan. Adv Exp Med Biol. 1999;467:461-8.

Kreider RB, Miriel V, Bertun E. Amino acid supplementation and exercise performance. Analysis of the proposed ergogenic value. Sports Medicine. 1993;16(3):190-209.

Levitan RD, Shen JH, Jindal R, Driver HS, Kennedy SH, Shapiro CM. Preliminary randomized double-blind placebo-controlled trial of tryptophan combined with fluoxetine to treat major depressive disorder: antidepressant and hypnotic effects. Journal of Psychiatry and Neuroscience. 2000;25(4):337-346.

Lieberman HR, Corkin S, Spring BJ, Wurtman RJ, Growdon JH. The effects of dietary neurotransmitter precursors on human behavior. American Journal of Clinical Nutrition. 1985;42(2):366-370.

Messiha FS. Fluoxetine: adverse effects and drug-drug interactions. Journal of Toxicology and Clinical Toxicology. 1993;31(4):603-630.

Milburn DS, Myers CW. Tryptophan toxicity: a pharmacoepidemiologic review of eosinophilia-myalgia syndrome. DICP. 1991;25(11):1259-1262.

Murray MF. Tryptophan depletion and HIV infection: a metabolic link to pathogenesis. Lancet Infectious Diseases. 2003;3(10):644-652.

Murray MF, Langan M, MacGregor RR. Increased plasma tryptophan in HIV-infected patients treated with pharmacologic doses of nicotinamide. Nutrition. 2001;17(7-8):654-656.

Nardil [package insert]. New York: Parke-Davis Division of Pfizer, Inc:2003.

Nardini M, De Stefano R, Iannuccelli M, Borghesi R, Battistini N. Treatment of depression with L-5-hydroxytryptophan combined with chlorimipramine, a double-blind study. International Journal of Clinical Pharmacological Research 1983;3(4):239-250.

Newsholme EA, Blomstrand E. Tryptophan, 5-hydroxytryptamine and a possible explanation for central fatigue. Advances in Experimental Medical Biology. 1995;384(:315-320.

Oduho GW, Han Y, Baker DH. Iron deficiency reduces the efficacy of tryptophan as a niacin precursor. Journal of Nutrition. 1994;124(3):444-450.

Office of Nutritional Products, Labeling, and Dietary Supplements. Center for Food Safety and Applied Nutrition. U.S. Food and Drug Administration. Information paper on L-tryptophan and 5-hydroxy-L-tryptophan. Issued February 2001. Available at: http://www.cfsan.fda.gov/%7Edms/ds-tryp1.html. Accessed November 4, 2003.

Perugini M, Mahoney C, Ilivitsky V, Young SN, Knott V. Effects of tryptophan depletion on acute smoking abstinence symptoms and the acute smoking response. Pharmacology, Biochemistry and Behavior. 2003;74(3):513-522.

Philen RM, Eidson M, Kilbourne EM, Sewell CM, Voorhees R. Eosinophilia-myalgia syndrome. A clinical case series of 21 patients. New Mexico Eosinophilia-Myalgia Syndrome Study Group. Archives of Internal Medicine. 1991;151(3):533-537.

Philen RM, Hill RH, Flanders WD, et al. Tryptophan contaminants associated with eosinophilia-myalgia syndrome. American Journal of Epidemiology. 1993;138(3):154-159.

Riemann D, Feige B, Hornyak M, Koch S, Hohagen F, Voderholzer U. The tryptophan depletion test: impact on sleep in primary insomnia - a pilot study. Psychiatry Research. 2002;109(2):129-135.

Schmidt HS. L-tryptophan in the treatment of impaired respiration in sleep. Bulletin of European Physiopathology and Respiration. 1983(6);19:625-629.

Seltzer S, Dewart D, Pollack R. The effects of dietary tryptophan on chronic maxillofacial pain and experimental pain tolerance. Journal of Psychiatric Research. 1982-83;17(2):181-186.

Sharma RP, Shapiro LE, Kamath SK, Soll EA, Watanabe MD, Davis JM. Acute dietary tryptophan depletion: effects on schizophrenic positive and negative symptoms. Neuropsychobiology. 1997;35(1):5-10.

Shibata K. Nutritional factors that regulate on [sic] the conversion of L-tryptophan to niacin. Advances on Experimental Medicine and Biology. 1999;467:711-716.

Shibata K, Fukuwatari T, Enomoto A, Sugimoto E. Increased conversion ratio of tryptophan to niacin by dietary di-n-butylphthalate. Journal of Nutritional Science and Vitaminology (Tokyo). 2001;47(3):263-266.

Sidransky H. Tryptophan and carcinogenesis: review and update on how tryptophan may act. Nutrition and Cancer. 1997;29(3):181-194.

Singhal AB, Caviness VS, Begleiter AF, et al. Cerebral vasoconstriction and stroke after use of serotonergic drugs. Neurology. 2002;58(1):130-133.

Smith KA, Fairburn CG, Cowen PJ. Symptomatic relapse in bulimia nervosa following acute tryptophan depletion. Archives of General Psychiatry. 1999;56(2):171-176.

Smith MJ, Mazzola EP, Farrell J, et al. 1,1'-ethylidenebis (l-tryptophan), structure determination of contaminant “97” – implicated in the eosinophilia-myalgia syndrome (EMS). Tetrahedron Letters. 1991;32(8):991-994.

Steinberg S, Annable L, Young SN, Liyanage N. A placebo-controlled study of the effects of L-tryptophan in patients with premenstrual dysphoria. Advances in Experimental Medicine and Biology. 1999;467:85-88.

Stockstill JW, McCall WD Jr, Gross AJ, Piniewski B. The effect of L-tryptophan supplementation and dietary instruction on chronic myofascial pain. Journal of the American Dental Association. 1989;118(4):457-460.

Sullivan EA, Kamb ML, Jones JL, et al. The natural history of eosinophilia-myalgia syndrome in a tryptophan-exposed cohort in South Carolina. Archives of Internal Medicine. 1996;156(9):973-979.

Thacker HL. Eosinophilia-myalgia syndrome: the Cleveland Clinic experience. Cleveland Clinic Journal of Medicine. 1991;58(5):400-408.

van Hall G, Raaymakers JS, Saris WH. Ingestion of branched-chain amino acids and tryptophan during sustained exercise in man: failure to affect performance. Journal of Physiology (London). 1995;486(Pt 3):789-794.

Varga J, Jimenez SA, Uitto J. L-tryptophan and the eosinophilia-myalgia syndrome: current understanding of the etiology and pathogenesis. Journal of Investigative Dermatology. 1993;100(1):97S-105S.

Werbach MR. Nutritional strategies for treating chronic fatigue syndrome. Alternative Medicine Review. 2000;5(2):93-108.

Wurtman RJ, Wurtman JJ. Brain serotonin, carbohydrate-craving, obesity and depression. Obesity Research. 1995;3(Suppl 4):477S-480S.

Yamamoto T, Castell LM, Botella J, et al. Changes in the albumin binding of tryptophan during postoperative recovery: a possible link with central fatigue? Brain Research Bulletin. 1997;43(1):43-46.


(Note: The above information is not intended to replace the advice of your physician, pharmacist, or other healthcare professional. It is not meant to indicate that the use of the product is safe, appropriate, or effective for you.)

© 2006-2018 LetsDrug.com Contact