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Common side effects when taken by mouth or injected include nausea, vomiting, headache, and anxiety. [12] Use on hemorrhoids is generally well tolerated. [12] Severe side effects may include a slow heart rate, intestinal ischemia, chest pain, kidney failure, and tissue death at the site of injection.
Phenylalanine is a precursor for tyrosine, the monoamine neurotransmitters dopamine, norepinephrine (noradrenaline), and epinephrine (adrenaline), and the biological pigment melanin. It is encoded by the messenger RNA codons UUU and UUC. Phenylalanine is found naturally in the milk of mammals.
l-DOPA is produced from the amino acid l-tyrosine by the enzyme tyrosine hydroxylase. l-DOPA can act as an l-tyrosine mimetic and be incorporated into proteins by mammalian cells in place of l-tyrosine, generating protease-resistant and aggregate-prone proteins in vitro and may contribute to neurotoxicity with chronic l-DOPA administration. [10]
A small subset of patients with hyperphenylalaninemia shows an appropriate reduction in plasma phenylalanine levels with dietary restriction of this amino acid; however, these patients still develop progressive neurologic symptoms and seizures and usually die within the first 2 years of life ("malignant" hyperphenylalaninemia).
Toxic levels of phenylalanine, along with insufficient levels of tyrosine, can interfere with infant development in ways that have permanent effects. The disease may present clinically with seizures , hypopigmentation (excessively fair hair and skin), and a "musty odor" to the baby's sweat and urine (due to phenylacetate , a carboxylic acid ...
Side effects of phenylpropanolamine include increased heart rate and blood pressure, among others. [13] [14] [15] [12] Rarely, phenylpropanolamine has been associated with hemorrhagic stroke. [11] [16] [13] Phenylpropanolamine acts as a norepinephrine releasing agent, thereby indirectly activating adrenergic receptors.
The amino acids phenylalanine and tyrosine are precursors for catecholamines. Both amino acids are found in high concentrations in blood plasma and the brain. In mammals, tyrosine can be formed from dietary phenylalanine by the enzyme phenylalanine hydroxylase, found in large amounts in the liver.
Pegvaliase, sold under the brand name Palynziq, is a medication used for the treatment of the genetic disease phenylketonuria (PKU). [5] [9] [10] It is a phenylalanine (Phe)‑metabolizing enzyme. [5]