Codeine is an opiate used to manage mild to moderate pain severe enough to require an opioid. Codeine is a selective agonist for the mu opioid receptor and has an affinity to delta and kappa-opioid receptors. In some countries, this drug is regulated under various narcotic control laws, because its chronic use can cause physical dependence. In others, it is available without a medical prescription in combination with paracetamol.

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.

Gentamicin C1 is a part of gentamicin C complex, containing gentamicin C1, gentamicin C1a, and gentamicin C2 which compose approximately 80% of gentamicin and have been found to have the highest antibacterial activity. Commercial gentamicin C is a mixture of gentamicin C1, C1a, and C2. Gentamicin C1 has a methyl group in the 6' position of the 2-amino-hexose ring and is N methylated at the same position. Gentamicin is a broad spectrum aminoglycoside antibiotic. Aminoglycosides work by binding to the bacterial 30S ribosomal subunit, causing misreading of t-RNA, leaving the bacterium unable to synthesize proteins vital to its growth. Aminoglycosides are useful primarily in infections involving aerobic, Gram-negative bacteria, such as Pseudomonas, Acinetobacter, and Enterobacter. In addition, some mycobacteria, including the bacteria that cause tuberculosis, are susceptible to aminoglycosides. Infections caused by Gram-positive bacteria can also be treated with aminoglycosides, but other types of antibiotics are more potent and less damaging to the host. In the past the aminoglycosides have been used in conjunction with penicillin-related antibiotics in streptococcal infections for their synergistic effects, particularly in endocarditis. Aminoglycosides are mostly ineffective against anaerobic bacteria, fungi and viruses. Aminoglycosides like gentamicin "irreversibly" bind to specific 30S-subunit proteins and 16S rRNA. Specifically gentamicin binds to four nucleotides of 16S rRNA and a single amino acid of protein S12. This interferes with decoding site in the vicinity of nucleotide 1400 in 16S rRNA of 30S subunit. This region interacts with the wobble base in the anticodon of tRNA. This leads to interference with the initiation complex, misreading of mRNA so incorrect amino acids are inserted into the polypeptide leading to nonfunctional or toxic peptides and the breakup of polysomes into nonfunctional monosomes. Gentamicin complex is used for treatment of serious infections caused by susceptible strains of the following microorganisms: P. aeruginosa, Proteus species (indole-positive and indole-negative), E. coli, Klebsiella-Enterobactor-Serratia species, Citrobacter species and Staphylococcus species (coagulase-positive and coagulase-negative).