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.

MERCAPTOMERIN is a mercurial diuretic used for the treatment of congestive heart failure. It is an effective diuretic not only when given intramuscularly and intravenously but also when given subcutaneously.

Metocurine, also known as dimethyltubocurarine, is a non-depolarizing muscle relaxant through the neuromuscular blockade. It antagonizes the neurotransmitter action of acetylcholine by binding competitively with cholinergic receptor sites on the motor end-plate. Patients chronically receiving anticonvulsants are relatively resistant to metocurine.

Cyclomethycaine (also known as Surfacaine) is a local anesthetic.

Sulfisoxazole is a sulfonamide antibacterial antibiotic. The sulfonamides are synthetic bacteriostatic antibiotics with a wide spectrum against most gram-positive and many gram-negative organisms. However, many strains of an individual species may be resistant. Sulfisoxazole acetyl in combination with erythromycin ethylsuccinate is used for treatment of ACUTE OTITIS MEDIA in children that is caused by susceptible strains of Haemophilus influenzae. Sulfisoxazole acetyl is a prodrug of sulfisoxazole. Acetyl group is added to make the drug poorly water soluble, and is hydrolyzed in vivo to the active drug. Sulfisoxazole and its acetylated metabolites are excreted primarily by the kidneys through glomerular filtration. Sulfisoxazole is a competitive inhibitor of the enzyme dihydropteroate synthetase. It inhibits bacterial synthesis of dihydrofolic acid by preventing the condensation of the pteridine with para-aminobenzoic acid (PABA), a substrate of the enzyme dihydropteroate synthetase. The inhibited reaction is necessary in these organisms for the synthesis of folic acid

Dihydrostreptomycin is an antibiotic compound derived from streptomycin by reduction with hydrogen. The primary mechanism of action of the antibiotic dihydrostreptomycin is binding to and modifying the function of the bacterial ribosome, thus leading to decreased and aberrant translation of proteins, in addition it binds mechanosensitive channel of large conductance (MscL) and modifies its conformation, thus allowing the passage of K+ and glutamate out of, and dihydrostreptomycin into, the cell. It has about the same degree of antibacterial activity as streptomycin, but it is less effective against some gram-negative microorganisms. Because it has a higher risk of irreversible deafness, and its effectiveness is no greater that that of streptomycin, dihydrostreptomycin is no longer used clinically. To date dihydrostreptomycin is approved for veterinary use to treat bacterial infections.

Isometheptene (usually as isometheptene mucate) is a sympathomimetic amine sometimes used in the treatment of migraines and tension headaches due to its vasoconstricting properties. Isometheptene's vasoconstricting properties arise through activation of the sympathetic nervous system via epinephrine and norepinephrine. These compounds elicit smooth muscle activation leading to vasoconstriction by interacting with cell surface adrenergic receptors.

Tetraethylammonium is an experimental drug with no approved indication or marketed formulation. Tetraethylammonium blocks of apamin-sensitive and insensitive Ca2(+)-activated K+ channels. It is a weak agonist of the nicotinic receptor. Tetraethylammonium produces transient reductions in blood pressure. Tetraethylammonium hydroxide is used as a soluble source of hydroxide ions and in the synthesis of ionic organic compounds.

Tetraethylammonium is an experimental drug with no approved indication or marketed formulation. Tetraethylammonium blocks of apamin-sensitive and insensitive Ca2(+)-activated K+ channels. It is a weak agonist of the nicotinic receptor. Tetraethylammonium produces transient reductions in blood pressure. Tetraethylammonium hydroxide is used as a soluble source of hydroxide ions and in the synthesis of ionic organic compounds.

Hexestrol (INN) (brand name Synoestrol, Estrifar, Estronal, numerous others), also known as hexoestrol, and dihydro-diethylstilbestrol, is a synthetic, non-steroidal estrogen of the stilbestrol group related to diethylstilbestrol that was used to treat estrogen deficiency but is now no longer employed medically. Hexestrol has also been available and used in ester form, including as hexestrol diacetate, hexestrol dicaprylate, hexestrol diphosphate, and hexestrol dipropionate.