Indinavir is an antiretroviral drug for the treatment of HIV infection. Indinavir is a protease inhibitor with activity against Human Immunodeficiency Virus Type 1 (HIV-1). Protease inhibitors block the part of HIV called protease. HIV-1 protease is an enzyme required for the proteolytic cleavage of the viral polyprotein precursors into the individual functional proteins found in infectious HIV-1. Indinavir binds to the protease active site and inhibits the activity of the enzyme. This inhibition prevents cleavage of the viral polyproteins resulting in the formation of immature non-infectious viral particles. Protease inhibitors are almost always used in combination with at least two other anti-HIV drugs.

Amifostine is an organic thiophosphate cytoprotective agent known chemically as 2-[(3¬ aminopropyl)amino]ethanethiol dihydrogen phosphate (ester), it’s adjuvant used in cancer chemotherapy and radiotherapy involving DNA-binding chemotherapeutic agents. It is marketed under the trade name Ethyol. Amifostine is a prodrug and is dephosphorylated by alkaline phosphatase in tissues to a pharmacologically active free thiol metabolite. This metabolite is believed to be responsible for the reduction of the cumulative renal toxicity of cisplatin and for the reduction of the toxic effects of radiation on normal oral tissues. The ability of Ethyol to differentially protect normal tissues is attributed to the higher capillary alkaline phosphatase activity, higher pH and better vascularity of normal tissues relative to tumor tissue, which results in a more rapid generation of the active thiol metabolite as well as a higher rate constant for uptake into cells. The higher concentration of the thiol metabolite in normal tissues is available to bind to, and thereby detoxify, reactive metabolites of cisplatin. This thiol metabolite can also scavenge reactive oxygen species generated by exposure to either cisplatin or radiation. Healthy cells are preferentially protected because amifostine and metabolites are present in healthy cells at 100-fold greater concentrations than in tumor cells.

Saquinavir (brand names Invirase and Fortovase) is an antiretroviral drug used together with other medications to treat or prevent HIV/AIDS. Saquinavir is an inhibitor of HIV protease. HIV protease is an enzyme required for the proteolytic cleavage of viral polyprotein precursors into individual functional proteins found in infectious HIV. Saquinavir is a peptide-like substrate analog that binds to the protease active site and inhibits the activity of the enzyme. Saquinavir inhibition prevents cleavage of the viral polyproteins resulting in the formation of immature noninfectious virus particles. The most frequent adverse events with saquinavir in either formulation are mild gastrointestinal symptoms, including diarrhea, nausea, loose stools & abdominal discomfort. Invirase is better tolerated than Fortovase.

Iobenguane I-131 is a radioactive therapeutic agent. The drug contains radioactive isotope I-131, which decays by electron emission with a half-life of about 8 days. By the chemical structure, iobenguane is similar to the neurotransmitter norepinephrine and is subject to the same uptake and regulation pathways. After intravenous administration, iobenguane I-131 accumulates within pheochromocytoma and paraganglioma cells, and radiation from the radioactive decay causes cell death and tumor necrosis. Iobenguane I-131 was approved by the FDA for the treatment of adult and pediatric patients with iobenguane scan positive, unresectable, locally advanced or metastatic pheochromocytoma or paraganglioma who require systemic anticancer therapy. Iobenguane I-131 is investigated in clinical trials as a treatment of neuroblastoma, ganglioneuroblastoma and other tumors of neuroendocrinal origin.

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.

Niclosamide is an antihelminth used against tapeworm infections. It may act by the uncoupling of the electron transport chain to ATP synthase. The disturbance of this crucial metabolic pathway prevents creation of adenosine tri-phosphate (ATP), an essential molecule that supplies energy for metabolism. Niclosamide works by killing tapeworms on contact. Adult worms (but not ova) are rapidly killed, presumably due to uncoupling of oxidative phosphorylation or stimulation of ATPase activity. The killed worms are then passed in the stool or sometimes destroyed in the intestine. Niclosamide may work as a molluscicide by binding to and damaging DNA. Niclosamide is used for the treatment of tapeworm and intestinal fluke infections: Taenia saginata (Beef Tapeworm), Taenia solium (Pork Tapeworm), Diphyllobothrium latum (Fish Tapeworm), Fasciolopsis buski (large intestinal fluke). Niclosamide is also used as a molluscicide in the control of schistosomiasis. Niclosamide was marketed under the trade name Niclocide, now discontinued.

Spectinomycin is an antibiotic produced by Streptomyces spectabilis. It is active against gram-negative bacteria and used for the treatment of acute gonorrheal urethritis and proctitis in the male and acute gonorrheal cervicitis and proctitis in the female when due to susceptible strains of Neisseria gonorrhoeae. In vitro studies have shown spectinomycin to be active against most strains of Neisseria gonorrhoeae (minimum inhibitory concentration <7.5 to 20 mcg/mL). Footprint studies indicate that spectinomycin exerts regional effects on ribosomal structure. Spectinomycin hydrochloride is an inhibitor of protein synthesis in the bacterial cell; the site of action is the 30S ribosomal subunit. The antibiotic is not significantly bound to plasma protein. Spectinomycin was discovered 1961. It is on the World Health Organization's List of Essential Medicines, the most important medications needed in a basic health system. This antibiotic is no longer available in the United States. Pfizer has discontinued distribution of spectinomycin (Trobicin) in the U.S. The drug continues to be distributed outside the U.S.

Cloxacillin is a derivative of penicillin for the treatment of broad spectrum of bacterial infections. The drug exerts its action by inhiiting bacterial beta-lactamase (penicillin-binding proteins).

Denatonium, usually available as denatonium benzoate (trade names Bitrex) is the most bitter chemical compound known, with bitterness thresholds of 0.05 ppm for the benzoate and 0.01 ppm for the saccharide. Scientists at Macfarlan Smith, Ltd. of Edinburgh, Scotland discovered Bitrex during research on derivatives of the anesthetic lidocaine. The extremely bitter taste proved effective in reducing ingestion by humans and animals. Denatonium is commonly included in placebo medications used in clinical trials to match the bitter taste of certain medications. Denatonium activates bitter taste receptor, mainly, TAS2R4, TAS2R8, TAS2R10, TAS2R13 on many cell types and plays important roles in chemical release, ciliary beating and smooth muscle relaxation through intracellular Ca(2+)-dependent pathways.

Ergonovine (also known as ergometrine) is the active water soluble component of ergot of rye. Ergonovine is being used as a maleate salt to prevent or treate postpartum haemorrhage and postabortion haemorrhage. Ergonovine stimulates alpha-adrenergic and serotonin receptors, thus activating contractions of uterine and vascular smooth muscle. Ergonovine may have depressant effect on CNS system as it binds to dopamine receptors.