L-5-Hydroxytrytophan (L-5HTP) - Investigational Drugs
Drug Name:L-5-Hydroxytrytophan (L-5HTP) - Investigational Drugs
List Of Brands:
Indication Type Description:
Drug Interaction
Indication
Adverse Reaction
Contra-Indications
Dosages/ Overdosage Etc
Pharmacology/ Pharmacokinetics
Drug Interaction:
Do not give monoamine oxidase inhibitors or resperine concurrently with
L-5-HTP- /carbidopa. Discontinue these drugs at least 2 weeks prior to initiating
treatment with L-5-HTP/carbidopa
Discontinue tricyclic antidepressants with a major serotonin reuptake inhibition mechanism
(ie. impipramine) prior to L-5-HTP/carbidopa therapy.
Also avoid serotonin receptor antagonists like methysergide or cyproheptadine, which
may reduce therapeutic effects of L-5-HTP/ carbidopa
Fenfuramine releases brain serotonin from serotonergic nerve terminals and may potentiate
L-5-HTP/carbidopa
Indication:
Treatment of post -anoxic intention mycoclonus.
Myoclonus is an uncommon neuromuscular movement disorder characterised by involuntary,
irregular muscle contraction.It is associated with a variety of brain lesions
Summary-
L-5HTP is available through a treatment IND under the FDAs orphan drug program from
Bolar Pharmaceuticals Inc. 130 Lincoln street, Copiague , NY 11726 , 516- 842-8383
The drug is beneficial to a small number of patients, further reasearch may elucidate
additional uses as we increase our understanding of the brains complex chemistry
Carbidopa may be obtained for use with L-5-HTP by contacting
Audrey A.Geist, MD, Professional information, MSD, West Point, PA 19486
215-661-7300
Adverse Reaction:
Most common-
GI - anorexia, nausea, diarrhea, and vomiting. Can be avoided or minimised by gradual
increases of L-5-HTP dosage. They rapidly disappear when the dose is reduced or
discontinued
The diarrhea will respond to therapy with diphenoxylate.The GI symptoms respond to
treatment with prochloroperazine or trimethoxybenzamide. The side effects eventually
disappear or diminish
Other adverse effects include mental changes, (ie euphoria which may progress to
hypomania, restlessness, rapid speech, anxiety, insomnia, aggresiveness, and agitation,
mydriasis, lightheadedness, sleepiness, blurring of vision, and bradycardia
Dysponea, sometimes accompanied by hyperventilation and lightheadedness, is rare.
L-5HTP/carbidopa might unmask subclinical scleroderma in patients with an abnormality
in kynurenine metabolism
Overdose- of L-5HTP/carbidopa can produce respiratory difficulties and hypotension
Contra-Indications:
Precautions-
Use L-5-HTP/carbidopa with caution in patients with severe emotional or psyciatric disorders
because of occassional mental side effects.
Mental depression has improved in some patients
Dosages/ Overdosage Etc:
Dosage-
Begin with 2mg L-5-HTP 4 times daily
Increase by 100mg/day every 3-5 days if there is no significant side effects.
If significant GI side effects develop, reduce the rate of increase to every 1 to 2 weeks
A reduction in myocolonus is usually first observed a6 600 to 1000mg/day( with carbidopa)
Usual optimal dose of L-5-HTP is between 1000 and 2000 mg/day in 4 divided doses.
Overdose
Overdose of L-5HTP/carbidopa can produce respiratory difficulties and hypotension
Pharmacology/ Pharmacokinetics:
Pharmacology-
L-5HTP is available as an -orphan drug- for the treatment of post-anoxic intension myocolonus.
Myocolonus is an uncommon neuromuscular movement disorder characterised by involuntary
irregular, muscle contraction. It is associted with a variety of brain lesions.
There is evidence that some of these disorders are related to brain neurotransmitter levels
or function, specifically serotinin. L-5-HTP is an aromatic amino acid , the immediate
precursor of serotonin
L-5HTP is administered with carpidopa , a peripheral dopa-decarboxylase inhibitor that
decreases the conversion of L-5HTP to serotonin in the extracerbral tissues.
This permits the administeration of lower doses of L-5-HTP and reduces the peripheral
GI side effects such as diarrhea and nausea
Pharmacokinetics-
When administred orally with carbidopa ( which produces a 5 to 15 fold increase in
plasma L-5HTP ) the systemic availability of L-5HTP is 47% to 84%
Peak plasma concentration of L-5HTP are reached at 1 to 3 hours.
The biological half-life of L-5HTP after pretreatment with carbidopa is 2 to 7 hours
