Histamine is a depressor amine derived by enzymatic decarboxylation of histidine. It is a powerful stimulant of gastric secretion, a constrictor of bronchial smooth muscle, a vasodilator, and a centrally acting neurotransmitter. Phosphate salt of jistamine was used as a diagnostic aid for evaluation of gastric acid secretory function. In addition, this compound is used as a positive control in evaluation of allergenic (immediate hypersensitivity or "Type I") skin testing. In addition, histamine is being studied for treatment of multiple sclerosis. It was approved, that histamine physiological functions are mediated by four 7-transmembrane G protein-coupled receptors (H1R, H2R, H3R, H4R) that are all targets of pharmacological intervention. The receptors display molecular heterogeneity and constitutive activity. H1R antagonists are long known antiallergic and sedating drugs, whereas the H2R led to the development of H2R-antagonists that revolutionized stomach ulcer treatment. The H3R is an auto receptor and heteroreceptor providing negative feedback on histaminergic and inhibition on other neurons. The H4R occurs on immuncompetent cells and the development of anti-inflammatory drugs is anticipated.

Levamisole (the trade name Ergamisol), an anthelminthic drug with immunological properties. It also has antitumor activity when administered with 5-fluorouracil in patients with Duke's C colorectal carcinoma; however, this use was discontinued. The mechanism of the antitumor effect is unknown but has been postulated to be related to levamisole's immunomodulatory properties. Levamisole can stimulate antibody formation to various antigens, enhance T-cell responses by stimulating T-cell activation and proliferation, potentiate monocyte and macrophage functions including phagocytosis, chemotaxis and increases motility, adherence, and chemotaxis. Levamisole inhibits alkaline phosphatase and possesses cholinergic activity. The mechanism of action of levamisole as an antiparasitic agent, for example, to treat ascariasis, relates to its agonistic activity to L-subtype nicotinic acetylcholine receptors in nematode muscles. In addition, levamisole was studied for preventing relapses of the steroid-sensitive idiopathic nephrotic syndrome (SSINS). It was shown, that alone or in combination with steroids, the drug can prolong the time to relapse and prevented recurrence during one year of treatment. However, these studies also were also discontinued.

P-32 is a radioactive isotope of phosphorus with a half-life of 14.29 days. Radioactive decay of P-32 produces beta-particles (electrons) which are able to penetrate tissue at a range of 3-8 mm. Phosphate ion P-32 has many applications in medicine and biology. P32 sodium phosphate was approved by the FDA for the treatment of polycythemia vera, chronic myelocytic leukemia, and chronic lymphocytic leukemia. P32-phosphate may also be used in the palliative treatment of selected patients with multiple areas of skeletal metastases. As metabolic uptake of phosphorus is selectively increased in malignant tissues, P-32 was also used for cancer diagnostics.

Novobiocin (also known as streptonivicin) is an aminocoumarin antibiotic, active against Staphylococcus epidermidis. Novobiocin and other aminocoumarin antibiotics act as a potent competitive inhibitor of DNA gyrase B. The oral form of the drug was withdrawn from the market in 1999 due to safety or effectiveness reasons. Later it was discovered that novobiocin inhibited Hsp90 and topoisomerase II, and novobiocin was investigated in clinical trials against metastatic breast cancer and non-small cell lung cancer. Topical form of novobiocin was investigated in combination with nalidixic acid for treatment of psoriasis.

Piperazine, a six membered nitrogen containing heterocycle, is of great significance to the rational design of drugs. This moiety can be found in a plethora of well-known drugs with various therapeutic uses, such as antipsychotic, antihistamine, antianginal, antidepressant, anticancer, antiviral, cardio protectors, anti-inflammatory, and imaging agents. Slight modification to the substitution pattern on the piperazine nucleus facilitates a recognizable difference in the medicinal potential of the resultant molecules. Piperazine has been used as an antihelmintic drug. Piperazine works by paralyzing the worms. They are then passed in the stool.

Pyridoxal phosphate (PLP, pyridoxal 5'-phosphate, P5P) is a coenzyme, the active form of vitamin B6. Pyridoxal 5′-phosphate (PLP) is used as a cofactor for a wide range of enzymes including mitochondrial cysteine desulfurase, cystathionine γ-synthase (CGS), ornithine 4,5-aminomutase (OAM), and d-serine dehydratase. The versatility of PLP arises from its ability to covalently bind the substrate, and then to act as an electrophilic catalyst, thereby stabilizing different types of carbanionic reaction intermediates. PLP acts as a coenzyme in all transamination reactions, in various beta-elimination reactions, in the condensation reaction in heme synthesis.

Phosphoric acid, also known as orthophosphoric acid, is used in dentistry and orthodontics to clean and roughen the surfaces of teeth where dental appliances or fillings will be placed. In addition, this acid is a part of product ProcalAmine, which is indicated for peripheral administration in adults to preserve body protein and improve nitrogen balance in well-nourished, mildly catabolic patients who require short-term parenteral nutrition. In combination with dextrose (glucose) and levulose (fructose), phosphoric acid relieves nausea due to upset stomach from intestinal flu, stomach flu, and food or drink indiscretions. In addition, homeopathic product, Brain power contains also phosphoric acid and this product is used to temporarily relieve symptoms of general physical weakness and listlessness, including: fatigue; sore muscles & joints; dry skin; absence of sexual desire; occasional sleeplessness.

Anhydrous dibasic calcium phosphate is a calcium salt of phosphoric acid. It is used as a diluent in pharmaceutical industry, in some toothpastes as a polishing agent. Calcium phosphate is generally recognized as safe by FDA. Dibasic calcium phosphate is ised as a supplement to treat conditions associated with calcium deficit, such as bone loss (osteoporosis), weak bones (osteomalacia/rickets), decreased activity of the parathyroid gland (hypoparathyroidism), and a certain muscle disease (latent tetany)