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Drug Interactions between 5-hydroxytryptophan and carbidopa

This report displays the potential drug interactions for the following 2 drugs:

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Moderate

carbidopa 5-hydroxytryptophan

Applies to: carbidopa and 5-hydroxytryptophan

GENERALLY AVOID: Coadministration with carbidopa may potentiate the pharmacologic effects of 5-hydroxytryptophan (5-HTP), which is converted to 5-hydroxytryptamine (5-HT), or serotonin, in vivo. Carbidopa inhibits the peripheral metabolism of 5-HTP, and this effect has been exploited in the treatment of certain neurological disorders such as postanoxic myoclonus to enhance the amount of 5-HTP that reaches the central nervous system. However, higher CNS levels of serotonin may also potentiate the risk of serotonin syndrome, which is a rare but potentially fatal condition thought to result from hyperstimulation of brainstem 5HT1A receptors. Pharmacodynamically, the combination has been associated with a scleroderma-like skin condition in several case reports. The mechanism is unknown.

MANAGEMENT: In general, 5-hydroxytryptophan should not be given with carbidopa. If the combination is used, close monitoring is recommended for signs and symptoms of excessive serotonergic activity such as CNS irritability, altered consciousness, confusion, myoclonus, ataxia, abdominal cramping, hyperpyrexia, shivering, pupillary dilation, diaphoresis, hypertension, and tachycardia.

References (4)
  1. Magnussen I, Van Woert MH (1982) "Human pharmacokinetics of long term 5-hydroxytryptophan combined with decarboxylase inhibitors." Eur J Clin Pharmacol, 23, p. 81-6
  2. Sternberg EM, Van Woert MH, Young SN, Magnussen I, Baker H, Gauthier S, Osterland CK (1980) "Development of a scleroderma-like illness during therapy with L-5- hydroxytryptophan and carbidopa." N Engl J Med, 303, p. 782-7
  3. Klepser T, Nisly N (2000) "5-Hydroxytryptophan (5-HTP) for treatment of depression." Alternative Medicine Alert, 3, p. 121-4
  4. Limbird LE, Gilman AG, eds., Hardman JG (2001) "Goodman and Gilman's the Pharmacological Basis of Therapeutics." New York, NY: McGraw-Hill

Drug and food interactions

No alcohol/food interactions were found. However, this does not necessarily mean no interactions exist. Always consult your healthcare provider.

Therapeutic duplication warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.

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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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