Phenylalanine (phenylalanine)
Phenylalanine Oral Powder In Packet (Ea)
Last reviewed · Source: First Databank (FDB) drug data
Overview
Generic name: phenylalanine
Drug class: Phenylalanine
Therapeutic class: Electrolyte Balance-Nutritional Products
Reference product & biosimilars
No reference, biosimilar or interchangeable associated with this drug.
Today’s intelligence on Phenylalanine
Indications
No indications are available for this drug.
Dosing
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Drug interactions
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Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.
Mixed & Indirect Sympathomimetics; Oral Phenylephrine/Maois
SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.
MECHANISM OF ACTION: Catecholamine stores increased by MAOIs can be released by indirect acting sympathomimetics such as ephedrine and amphetamine. MAO inhibitors also interfere with gut and liver metabolism of direct acting sympathomimetics (e.g oral phenylephrine).
CLINICAL EFFECTS: Concurrent use of MAOIs may result in potentiation of sympathomimetic effects, which may result in headaches, hypertensive crisis, toxic neurological effects, and malignant hyperpyrexia. Fatalities have occurred.
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: Concurrent use of monoamine oxidase inhibitors and sympathomimetics is contraindicated. The manufacturers of sympathomimetic agents recommend waiting 14 days after discontinuation of MAO inhibitors before initiating the sympathomimetic.
DISCUSSION: Indirect acting sympathomimetic amines may cause abrupt elevation of blood pressure when administered to patients taking monoamine oxidase inhibitors, resulting in a potentially fatal hypertensive crisis. Mixed (direct and indirect) acting sympathomimetics have also been shown to interact with monoamine oxidase inhibitors depending on their degree of indirect action. The direct-acting sympathomimetics have not been reported to interact. Dopamine is metabolized by monoamine oxidase, and its pressor effect is enhanced by monoamine oxidase inhibitors. Linezolid is another antibacterial with monoamine oxidase inhibitor properties. Metaxalone is a weak inhibitor of MAO. Foods containing large amounts of tyramine have also been implicated in this interaction. Methylene blue, when administered intravenously, has been shown to reach sufficient concentrations to be a potent inhibitor of MAO-A. At recommended dosages, rasagiline, oral selegiline, and transdermal selegiline up to 6mg/day are selective for MAO-B; however, at higher dosages they have been shown to lose their selectivity. One or more of the drug pairs linked to this monograph have been included in a list of interactions that should be considered "high-priority" for inclusion and should not be inactivated in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology.
Severe Interaction: Action is required to reduce the risk of severe adverse interaction.
Aspartame; Phenylalanine; Tyrosine/Nitisinone
SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.
MECHANISM OF ACTION: Aspartame contains phenylalanine, which is metabolized into tyrosine. Nitisinone prevents the breakdown of tyrosine.(1)
CLINICAL EFFECTS: Elevated levels of tyrosine can cause vision changes (cornea ulcers, corneal opacities, keratitis, conjunctivitis, eye pain, and photophobia), skin problems (painful hyperkeratotic plaques on the soles and palms), and nervous system toxicity (variable degrees of mental retardation and developmental delay).
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: Patients receiving nitisinone should following dietary restrictions concerning the consumption of aspartame, phenylalanine, and tyrosine, including medications that contain these ingredients.(1)
DISCUSSION: In most patients, eye symptoms resulting from elevated tyrosine levels were transient, lasting less than one week; however, six patients had prolonged episodes lasting up to almost 2 years.(1)
Mixed & Indirect Sympathomimet; Oral Phenylephrine/Slt Maois
SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.
MECHANISM OF ACTION: Catecholamine stores increased by MAOIs can be released by indirect acting sympathomimetics such as ephedrine and amphetamine. MAO inhibitors also interfere with gut and liver metabolism of direct acting sympathomimetics (e.g oral phenylephrine).
CLINICAL EFFECTS: Concurrent use of MAOIs may result in potentiation of sympathomimetic effects, which may result in headaches, hypertensive crisis, toxic neurological effects, and malignant hyperpyrexia. Fatalities have occurred with combinations of sympathomimetics and MAO-A inhibitors.
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: Concurrent use of MAO-A inhibitors and sympathomimetics is contraindicated. The manufacturers of sympathomimetic agents recommend waiting 14 days after discontinuation of MAO inhibitors before initiating the sympathomimetic. Patients receiving indirect acting sympathomimetics should not receive linezolid unless they are monitored for potential increases in blood pressure. Initial dosages of dopamine should be reduced. At recommended dosages, oral selegiline and transdermal selegiline up to 6mg/day are selective for MAO-B; however, at higher dosages they have been shown to lose their selectivity. Patients receiving higher dosages of selegiline should be considered susceptive to this interaction.
DISCUSSION: Indirect acting sympathomimetic amines may cause abrupt elevation of blood pressure when administered to patients taking monoamine oxidase inhibitors, resulting in a potentially fatal hypertensive crisis. Mixed (direct and indirect) acting sympathomimetics have also been shown to interact with monoamine oxidase inhibitors depending on their degree of indirect action. The direct-acting sympathomimetics have not been reported to interact. Dopamine is metabolized by monoamine oxidase, and its pressor effect is enhanced by monoamine oxidase inhibitors. Foods containing large amounts of tyramine have also been implicated in this interaction. A significant pressor response was observed in normal subjects receiving linezolid and tyramine doses of more than 100 mg. Administration of linezolid (600 mg BID for 3 days) with pseudoephedrine (60 mg q 4 hours for 2 doses) increased blood pressure by 32 mmHg. Administration of linezolid (600 mg BID for 3 days) with phenylpropanolamine (25 mg q 4 hours for 2 doses) increased blood pressure by 38 mmHg. One or more of the drug pairs linked to this monograph have been included in a list of interactions that should be considered "high-priority" for inclusion and should not be inactivated in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology.
Mixed & Indirect Sympathomimet;Oral Phenylephrine/Rasagiline
SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.
MECHANISM OF ACTION: Catecholamine stores increased by MAOIs can be released by indirect acting sympathomimetics such as ephedrine and amphetamine. MAO inhibitors also interfere with gut and liver metabolism of direct acting sympathomimetics (e.g oral phenylephrine).
CLINICAL EFFECTS: Concurrent use of MAOIs may result in potentiation of sympathomimetic effects, which may result in headaches, hypertensive crisis, toxic neurological effects, and malignant hyperpyrexia. Hypertensive crisis has been reported in patients taking recommended doses of rasagiline with sympathomimetic agents.
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: At recommended dosages, rasagiline is selective for MAO-B; however, at higher dosages it has been shown to lose its selectivity. Patients receiving higher dosages of rasagiline should be considered susceptive to this interaction. Concurrent use should be approached with caution.
DISCUSSION: Indirect acting sympathomimetic amines may cause abrupt elevation of blood pressure when administered to patients taking monoamine oxidase inhibitors, resulting in a potentially fatal hypertensive crisis. Mixed (direct and indirect) acting sympathomimetics have also been shown to interact with monoamine oxidase inhibitors depending on their degree of indirect action. The direct-acting sympathomimetics have not been reported to interact. Dopamine is metabolized by monoamine oxidase, and its pressor effect is enhanced by monoamine oxidase inhibitors.
There are no moderate interactions for this drug.
Contraindications
There is no enhanced messaging for this drug.
- Phenylketonuria
There are no severe contraindications for this drug.
There are no moderate contraindications for this drug.
Adverse reactions
There is no enhanced messaging for this drug.
There are no severe adverse reactions for this drug.
There are no less severe adverse reactions for this drug.
Precautions
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ICD codes
No ICD codes are available for this drug.
Formulary status
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Last reviewed · Source: First Databank (FDB) drug data
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