Phenothiazine, the parent compound of a multitude of present-day drugs, has been employed on an extensive scale for its insecticidal, fungicidal, antibacterial and anthelmintic properties. Phenothiazine was formerly used as an insecticide and as a drug to treat infections with parasitic worms (antihelminthic) in livestock and people. It was introduced as antihelminthic in livestock in 1940 and is considered, with thiabendazole, to be the first modern antihelminthic. Almost a catholicon, its widespread use in animals and man has led to the uncovering of many adverse reactions encompassing effects on blood elements, neuromuscular problems and photosensitization. Its potential side effects have now limited its use. The chemical structure of phenothiazine provides a most valuable molecular template for the development of agents able to interact with a wide variety of biological processes. Synthetic phenothiazines (with aliphatic, methylpiperazine, piperazine-ethanol, piperazine-ethyl, or piperidine side-chain) and/or phenothiazine-derived agents e.g., thioxanthenes, benzepines, imonostilbenes, tricyclic antidepressants, dimetothiazine, and cyproheptadine have been effective in the treatment of a number of medical conditions with widely different etiology. These include various currently clinically used drugs for their significant antihistamic, antipsychotic, anticholinergic (antiparkinson), antipruritic, and/or antiemetic properties.

Theofibrate (Etofylline clofibrate, trade name Duolip) is the clofibric acid ester of theophylline, used for the treatment of hyperlipoproteinaemia with elevated triglycerides and cholesterol. The low dose of Etophylline clofibrate (750mg) has a similar lipid-lowering effect as pure clofibrate (1500mg), probably due to a synergistic hypolipidemic effect with theophylline, which has no lipid-lowering effect per se. Secondly, etophylline clofibrate substantially decreases platelet aggregability and plasma viscosity, properties which may be desirable in the prevention of coronary heart disease (CHD). Finally, etophylline clofibrate is clearly a less potent inducer of peroxisomal proliferation in the rat liver than clofibrate, bezafibrate or fenofibrate. Theofibrate increases lipoprotein lipase activity to promote the conversion of Very low-density lipoprotein (VLDL) to Low-density lipoprotein (LDL), and hence reduce the level of VLDL.

Salinazid (Acozid, Nupasal-213) is an antibacterial agent used primarily as a tuberculostatic. It used to be the treatment of choice for tuberculosis.

Nequinate is an aid in the prevention of coccidiosis caused by E. tenella, E. necatrix, E. acervulina, E. maxima, E. brunetti, and E. mivati.

Etofylline [7-(2-hydroxyethyl)theophylline] is a N-7-substituted derivative of theophylline, a smooth muscle relaxant. Etofylline is used to relieve bronchoconstriction. It may act as a phosphodiesterase inhibitor and adenosine receptor antagonist.

Nilvadipine (NIVADIL®) is a L-type calcium channel blocker for treatment of hypertension. It inhibits the influx of extracellular calcium through myocardial and vascular membrane pores by physically plugging the channel. The decrease in intracellular calcium inhibits the contractile processes of smooth muscle cells, causing dilation of the coronary and systemic arteries, increased oxygen delivery to the myocardial tissue, decreased total peripheral resistance, decreased systemic blood pressure, and decreased afterload.

Acivicin is a modified amino acid and structural analog of glutamine, that irreversibly inhibits glutamine-dependent amidotransferases involved in nucleotide and amino acid biosynthesis. Acivicin is a potent antitumor agent that induces apoptosis in human lymphoblastoid cells. Phase I dose-escalating studies conducted in cancer patients administered acivicin showed reversible, dose-limiting CNS toxicity, characterized by lethargy, confusion and decreased mental status.

Benzydamine (benzydamine hydrochloride, PHARIXIA®) is a benzyl-indazole having analgesic, antipyretic, and anti-inflammatory effects. It is indicated for the relief of pain in acute sore throat and for the symptomatic relief of oro-pharyngeal mucositis caused by radiation therapy.

Methylthiouracil is an orally active thyroid enzyme activity inhibitor. Methylthiouracil was introduced in the mid-1940s for the treatment of hyperthyroidism. Methylthiouracil is no longer in clinical use in most countries, although it may be used to a limited degree in some eastern European countries. Methylthiouracil possess anti-inflammatory effects in vitro and in vivo and was found effective in a murine model of sepsis.

Famphur is an insecticide and antihelmenthic. Famphur is approved in cattle as a pour-on (NADA 34-697; 21 CFR 524.900) and as medicated feed (NADA 34-266; 21 CFR 558.254). It is a component of the FDA-approved TRAMISOL X-TRA Combination Paste, used for the treatment of cattle infected with the following parasites: Stomach worms (Haemonchus, Trichostrongylus, Ostertagia), intestinal worms (Trichostrongylus, Cooperia, Nematodirus, Bunostomum, Oesophagostomum), lungworms (Dictyocaulus), cattle grubs (Hypoderma), biting lice (Bovicola), and sucking lice (Linognathus, Solenoptes). Famphur is a cholinesterase-inhibiting drug.