Desyrel
Desyrel
Generic Name
Desyrel
Brand Names
for the essential amino acid tryptophan. Once marketed as a prescription antidepressant, it is now primarily available as a dietary supplement and used anecdotally for mild depression, anxiety, and sleep disorders.
Mechanism
- Serotonin precursor: Tryptophan is hydroxylated to 5‑hydroxytryptophan and decarboxylated to serotonin (5‑HT) in the CNS.
- Melatonin synthesis: A fraction is further converted to melatonin by the pineal gland, contributing to circadian rhythm regulation.
- Indirect monoamine influence: By raising central serotonin stores, it can modestly inhibit reuptake pathways and enhance serotonergic tone, albeit less potently than SSRIs.
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Pharmacokinetics
| Parameter | Value / Notes |
| Absorption | Oral bioavailability ~50‑70 %. Peak plasma ~2–3 h post‑dose. |
| Distribution | Widely distributed; crosses the blood‑brain barrier. Protein binding ~10 %. |
| Metabolism | Primarily hepatic via tryptophan hydroxylase to serotonin and via tryptophan‑2,3‑dioxygenase to kynurenine. |
| Elimination | Renal excretion of metabolites; terminal half‑life ~1–1.5 h. |
| Drug interactions | ↑risk of serotonin syndrome when combined with serotonergic agents (SSRIs, SNRIs, MAOIs, tramadol). |
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Indications
- Mild‑to‑moderate depression (often as adjunct or in patients intolerant to SSRIs).
- Insomnia and sleep disturbances (due to melatonin production).
- Anxiety and pre‑menstrual mood symptoms (mild relief reported).
- Adjunctive use in fibromyalgia or chronic fatigue where mood regulation may help.
*(Note: FDA has not approved tryptophan for depression; evidence is limited and largely anecdotal.)*
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Contraindications
- Serotonergic drug therapy: MAOIs, SSRIs, SNRIs, duloxetine, tramadol, linezolid, or any agent that elevates serotonin.
- Pregnancy & lactation: Use only if benefits outweigh risks; data limited.
- Severe hepatic impairment: Reduced metabolism may lead to accumulation.
- History of hypersensitivity to tryptophan or any ingredient.
- Risk of serotonin syndrome: Monitor for agitation, hyperreflexia, clonus, seizures.
- Potential for eosinophilic meningoencephalitis: Rare, serious.
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Dosing
| Population | Typical Dose | Administration |
| Adults (mild depression) | 500 mg 3–4 × daily (1–2 g / day) | Oral, preferably with food |
| Adults (sleep) | 500–1000 mg nightly | Oral |
| Pediatrics (≥12 y) | 5 mg/kg / day | Oral, split throughout day |
*Start low; titrate by 250–500 mg increments every 3–5 days based on response and tolerability.*
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Adverse Effects
- Common:
- Drowsiness, fatigue
- Nausea, GI upset
- Headache, dizziness
- Mild sedation (especially at higher doses)
- Serious:
- Serotonin syndrome (agitation, tremor, autonomic instability) in drug‑drinking combinations.
- Eosinophilic meningoencephalitis (rare; severe headache, fever, seizures).
- Allergic rash, anaphylaxis in susceptible individuals.
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Monitoring
- Baseline: Liver function tests (ALT/AST) if hepatic disease.
- During therapy:
- Watch for signs of serotonin syndrome if co‑administered with serotonergic drugs.
- Assess sleep quality and daytime alertness.
- Monitor weight and appetite (tryptophan may influence metabolic parameters).
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Clinical Pearls
- Adjunct, not stand‑alone: Tryptophan’s modest serotonergic effect makes it best suited as an adjunctive agent for mild symptoms.
- Avoid “combo” pitfalls: Do *not* stack tryptophan with SSRIs, SNRIs, or MAOIs unless under close supervision; the risk of serotonin syndrome outweighs benefit.
- Timing matters: Evening dosing enhances sleep benefit due to melatonin conversion; morning doses may reduce daytime sedation.
- Dietary interplay: High‑protein meals can compete for intestinal absorption; a moderate‑protein snack can optimize uptake.
- Quality control: Because tryptophan is often marketed as a supplement, verify product purity and dosage—contamination can lead to serious toxicity.
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• Key Takeaway:
Desyrel (tryptophan) is a natural serotonergic precursor with modest antidepressant and sleep‑promoting properties. Use it cautiously, avoid serotonergic drug combinations, and monitor for both common sedation and rare, serious adverse reactions.