Protirelin is the pharmaceutically available synthetic analogue of the endogenous peptide thyrotropin-releasing hormone (TRH). It is a tri-peptide tropic hormone, released by the hypothalamus, which stimulates the release of Thyroid Stimulating Hormone (TSH) and prolactin from the anterior pituitary. Although not currently available in any FDA-approved product, protirelin is a component of the TRH Test where it is used to test the response of the anterior pituitary gland in conditions such as secondary hypothyroidism and acromegaly. TRH is indicated as an adjunctive agent in the diagnostic assessment of thyroid function. As an adjunct to other diagnostic procedures, testing with TRH (protirelin) may yield useful information in patients with pituitary or hypothalamic dysfunction. TRH is indicated as an adjunct to evaluate the effectiveness of thyrotropin suppression with a particular dose of T4 in patients with nodular or diffuse goiter. A normal TSH baseline value and a minimal difference between the 30 minute and baseline response to TRH injection would indicate adequate suppression of the pituitary secretion of TSH. TRH may be used, adjunctively, for adjustment of thyroid hormone dosage given to patients with primary hypothyroidism. A normal or slightly blunted TSH response, thirty minutes following TRH injection, would indicate adequate replacement therapy. Side effects have been reported in about 50% of the patients tested with TRH. Generally, the side effects are moor, have occurred promptly, and have persisted for only a few minutes following injection. Cardiovascular reactions: Marked changes in blood pressure, including both hypertension and hypotension with or without syncope, have been reported in a small number of patients. Endocrine reaction: Breast enlargement and leakage in lactating women for up to two or three days. Other reactions: Headaches, sometimes severe, and transient amaurosis in patients with pituitary tumors. Rarely, convulsions may occur in patients with predisposing conditions, e.g., epilepsy, brain damage. Nausea; urge to urinate; flushed sensation; light-headedness; bad taste in mouth; abdominal discomfort; and dry mouth. Less frequently reported were: Anxiety; sweating; tightness in the throat; pressure in the chest; tingling sensation; drowsiness; and allergic reactions. Pharmacologically, TRH increases the release of the thyroid stimulating hormone (TSH) from the anterior pituitary. Prolactin release is also increased. It has recently been observed that approximately 65% of acromegalic patients tested respond with a rise in circulating growth hormone levels; the clinical significance is as yet not clear. Following intravenous administration, the mean plasma half-life of protirelin in normal subjects is approximately five minutes. TSH levels rise rapidly and reach a peak at 20 to 30 minutes. The decline in TSH levels takes place more slowly, approaching baseline levels after approximately three hours.

D-Xylose is a sugar originally isolated from wood. D-Xylose is a colorless to white crystalline powder that is used in food products such as breads, butter, and beverage industry as flavoring agent and sweetener. Specifically, D-Xylose is used to sweeten products intended for use by obese and diabetic customers because it is a non-caloric sweetener. It has a cool and refreshing taste and has the same sweetness as sucrose, and it is often used to sweeten a wide variety of foods and beverages such as spices, meat products, butter, etc. D-Xylose is a sugar widely used as diabetic sweetener in food and beverage. is a sugar first isolated from wood, and named for it. Xylose is classified as a monosaccharide of the aldopentose type, which means that it contains five carbon atoms and includes a formyl functional group. It is derived from hemicellulose, one of the main constituents of biomass. Like most sugars, it can adopt several structures depending on conditions. With its free carbonyl group, it is a reducing sugar. D-xylose absorbtion test has been used for diagnosis of intestinal malabsorption.

Phenylalanine is a biologically essential amino acid that acts as a precursor to tyrosine and the catecholamines (epinephrine, norepinephrine, dopamine, and tyramine), and is a constituent of many central nervous system neuropeptides. Normal dietary levels of phenylalanine are approximately 1-2 grams daily. Phenylalanine appears in two forms which are identical mirror images of each other: L-phenylalanine, a nutritional supplement, and D-phenylalanine, an effective painkiller and antidepressant due to its ability to inhibit the breakdown of enkephalins, the brain’s natural pain killers.

Tryptophan is alpha-aminoacid that is used in the biosynthesis of proteins. It is essential aminoacid in humans, meaning the body cannot synthesize and it must be obtained from the diet. Tryptophan is a precursor of serotonin, and as such is sold over the counter in many countries as a dietary supplement for use as an antidepressant, anxiolytic and sleep aid, however application of tryptophan in these indications is not approved by FDA.

Alanine is a non-essential aminoacid encoded by GCU, GCC, GCA, and GCG codons. Besides being a building block of proteins, alanine plays a key role in glucose-alanine cycle. Alanine is medically used as a dietary supplement for conditions such as fructose intolerance, muscle atrophy, low birth weight.

Isoleucine is an essential α-amino acid that is used in the biosynthesis of proteins. L-isoleucine is commonly used in parenteral and enteral nutrition. It is used in combination with the other branched chain amino acids to improve the nutritional status of patients with hepatic diseases. BCAAs serve as important fuel sources for skeletal muscle during periods of metabolic stress

Lysing is an essential basic amino-acid encoded by codone AAA and AAG, and used in the biosynthesis of proteins. The daily requirement for lysine is 38 mg/kg body weight. The most rich source of lysine is fish, beef, chicken. In a clinical study lysine supplements was found to be an effective for reduction of occurrence, severity and healing time for recurrent HSV infection, however Cochrane Review concluded that the evidence is insufficient. Lysine was investigated for improving anxiety, ameliorating angina prectoris. Lysine acetylsalicylate has been used to treat pain and to detoxify the body after heroin use. Lysine clonixinate has been used for its analgesic properties for the treatment of migraine headaches and other painful conditions. However, limited clinical trials exist for these conditions.

Histidine is an essential amino acid. L-histidine is converted to histamine by histidine decarboxylase, a pyridoxal 5'-phosphate-dependent enzyme. The copper(II)–l-histidine (1:2 complex at physiological pH) has been widely used in the treatment of Menkes disease (a genetic neurodegenerative disorder that leads to early death in the children due to impaired copper metabolism) and more recent use has been reported in the treatment of infantile hypertrophic cardioencephalomyopathy (a condition caused by mutations in SCO2, a cytochrome c oxidase assembly gene). CUSTODIOL HTK (Histidine-tryptophan-ketoglutarate) Solution is indicated for perfusion and flushing of donor kidneys, liver, and heart prior to removal from the donor or immediately after removal from the donor.

Valine is an α-amino acid that is used in the biosynthesis of proteins. It is essential in humans, meaning the body cannot synthesize it and thus it must be obtained from the diet. There is a mixed scientivic evidence that as a dietary supplement valine improves training efficacy, delays central fatigue.

Tyrosine (L-form) is a non-essential amino acid, which is primarily required for the protein synthesis. This amino acid is the precursor of dopamine, norepinephrine, and epinephrine; therefore the lower concentration of tyrosine could be a peripheral marker of the hyperdopaminergic condition hypothesized to explain psychosis. Tyrosine supplements can improve cognition, increase energy, reduce anxiety, reduce depression, reduce levels of pain.