Mibefradil is a calcium channel blocker, chemically unlike other compounds in the class, that was approved by the Food and Drug Administration (FDA), U.S.A. in June 1997 for the treatment of patients with hypertension and chronic stable angina. Shortly following its introduction, mibefradil was withdrawn from the market in the U.S.A. as well as in Europe. The reason for the voluntary withdrawal of the drug by Roche laboratories was claimed to be the result of new information about potentially harmful interactions with other drugs. Mibefradil is calcium channel blocker with moderate selectivity for T-type Ca2+ channels displaying IC50 values of 2.7 uM and 18.6 uM for T-type and L-type channels respectively. Mibefradil is a tetralol calcium channel blocking agent that inhibits the influx of calcium ions across both the T (low-voltage) and L (high-voltage) calcium channels of cardiac and vascular smooth muscle, with a greater selectivity for T channels. Vasodilation occurs in vascular smooth muscle, causing a decrease in peripheral vascular resistance and a resulting decrease in blood pressure. Mibefradil causes a slight increase in cardiac output during chronic dosing. Mibefradil slows sinus and atrioventricular (AV) node conduction, producing a slight reduction in heart rate and a slight increase in the PR interval. It has also been shown to slightly lengthen the corrected sinus node recovery time and AH interval and to raise the Wenckebach point. The mechanism by which mibefradil reduces angina is not known, but is thought to be attributed to a reduction in heart rate, total peripheral resistance (afterload), and the heart rate-systolic blood pressure product at any given level of exercise. The result of these effects is a decrease in cardiac workload and myocardial oxygen demand. Mibefradil has been repurposed from an abandoned antihypertensive to a targeted solid tumor treatment, and it has been rescued from drug-drug interactions by using short-term dose exposure. Tau is using the early success of mibefradil as a proof of concept to build a platform technology of Cav3 blockers for broad antitumor applications in combination with new targeted cancer therapies, well-established.

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.

Spirapril (Renormax) is an ACE inhibitor antihypertensive drug used to treat hypertension. Spiraprilat, the active metabolite of spirapril, competes with angiotensin I for binding at the angiotensin-converting enzyme, blocking the conversion of angiotensin I to angiotensin II. Inhibition of ACE results in decreased plasma angiotensin II. As angiotensin II is a vasoconstrictor and a negative-feedback mediator for renin activity, lower concentrations result in a decrease in blood pressure and stimulation of baroreceptor reflex mechanisms, which leads to decreased vasopressor activity and to decreased aldosterone secretion. Spiraprilat may also act on kininase II, an enzyme identical to ACE that degrades the vasodilator bradykinin.

Cisapride is chemically related to metoclopramide, but unlike metoclopramide, it does not cross the blood-brain barrier or have antidopaminergic effects. Cisapride is a serotonin-4 (5-HT4) receptor agonist. Cisapride was indicated for the symptomatic treatment of adult patients with nocturnal heartburn due to gastroesophageal reflux disease. The Food and Drug Administration (FDA) in America stopped the marketing of cisapride as of 14th July 2000. They had received at least 341 reports of heart rhythm abnormalities and these led to 80 deaths. Other reported adverse effects are: headache, diarrhea, abdominal pain, nausea, constipation. Cisapride for animals has been found helpful in some cases of megaesophagus and is a common treatment for feline megacolon. Clarithromycin, erythromycin, and troleandomycin markedly inhibit the metabolism of cisapride. Concurrent administration of certain anticholinergic compounds, such as belladonna alkaloids and dicyclomine, would be expected to compromise the beneficial effects of cisapride.

Temafloxacin (marketed by Abbott Laboratories as Omniflox) is almost completely absorbed from the gastrointestinal tract, with an absolute bioavailability of approximately 93% and is not greatly affected by food. The time to reach peak concentrations ranges between 2 and 3 hours. In addition to the broad spectrum of activity all fluoroquinolones have against gram-negative pathogens, temafloxacin has improved antimicrobial activity against gram-positive aerobic cocci, intracellular microorganisms, and anaerobes. The bactericidal action of temafloxacin results from interference with the activity of the bacterial enzymes DNA gyrase. Omniflox was approved to treat lower respiratory tract infections, genital and urinary infections like prostatitis, and skin infections in the U.S. by the Food and Drug Administration in January 1992. Severe adverse reactions, including allergic reactions and hemolytic anemia, developed in about fifty patients during the first four months of its use, leading to three patient deaths. Abbott withdrew the drug from sale in June 1992.

Loracarbef (KT3777) is carbacephem antibiotic structurally identical to cefaclor, except that the sulfur atom of position 1 of the cephem nucleus has been replaced by carbon. It showed good affinity for penicillin-binding proteins. At low concentrations (< 2 mg/L) in vitro, it inhibits Streptococcus pneumoniae, S. pyogenes, beta-haemolytic streptococci groups B, C and G. Proteus mirabilis and Moraxella catarrhalis, including beta-lactamase-producing strains. At therapeutic plasma concentrations it is also active in vitro against most strains of Staphylococcus aureus, S. saprophyticus, Escherichia coli and beta-lactamase-positive and -negative strains of Haemophilus influenzae. Loracarbef has been indicated in the treatment of patients with mild to moderate infections caused by susceptible strains of the designated microorganisms.

Altretamine is structurally similar to the alkylating agent triethylenemelamine (tretamine). Although Altretamine structurally resembles an alkylating agent, it has not been found to have alkylating activity in vitro. The precise mechanism of Altretamine cytotoxicity is unknown, although several proposals have been made. Altretamine requires N-demethylation in the liver to produce reactive intermediates (formaldehyde and/or iminium species) which covalently bind to DNA, resulting in DNA damage, or act as alkylating agents. Altretamine is used as a palliative treatment for persistent or recurrent ovarian cancer following treatment failure with a cisplatin- or alkylating agent-based combination. Side effects of Altretamine include nausea and vomiting, neurotoxicity (mood disorders, disorders of consciousness, ataxia, dizziness, vertigo), mild to moderate dose-related myelosuppression. Altretamine has been shown to be embryotoxic and teratogenic in rats and rabbits and may cause fetal damage when administered to a pregnant woman. Under the trade name Hexalen, Altretamine, is an antineoplastic agent. It is indicated for use as a single agent in the palliative treatment of patients with persistent or recurrent ovarian cancer following first-line therapy with a cisplatin and/or alkylating agent-based combination.

Bepridil is a calcium channel blocker that has well characterized anti-anginal properties and known but poorly characterized type 1 anti-arrhythmic and anti-hypertensive properties. It has inhibitory effects on both the slow calcium and fast sodium inward currents in myocardial and vascular smooth muscle, interferes with calcium binding to calmodulin, and blocks both voltage and receptor operated calcium channels. It is used to treat hypertension (high blood pressure), angina (chest pain), sustained atrial fibrillation and tachyarrhythmia. The most common side effects were upper gastrointestinal complaints (nausea, dyspepsia or GI distress), diarrhea, dizziness, asthenia and nervousness. Certain drugs could increase the likelihood of potentially serious adverse effects with bepridil hydrochloride. In general, these are drugs that have one or more pharmacologic activities similar to bepridil hydrochloride, including anti-arrhythmic agents such as quinidine and procainamide, cardiac glycosides and tricyclic anti-depressants. Anti-arrhythmics and tricyclic anti-depressants could exaggerate the prolongation of the QT interval observed with bepridil hydrochloride. Cardiac glycosides could exaggerate the depression of AV nodal conduction observed with bepridil hydrochloride.

Pipecuronium is a piperazinyl androstane derivative, which is a non-depolarizing neuromuscular blocking agent, which was approved under brand name arduan for injection. It is a long-acting neuromuscular blocking agent, indicated as an adjunct to general anesthesia, to provide skeletal muscle relaxation during surgery. Arduan can also be used to provide skeletal muscle relaxation for endotracheal intubation. Pipecuronium undergoes very little metabolism and is excreted by the kidney and the liver. Owing to its relatively long duration of action and to the residual postoperative neuromuscular block (RPONB), the use of pipecuronium was discontinued in the United States and in several European countries. Because of its excellent safety profile, the use of pipecuronium has been maintained in several countries including China, Russia, Brazil, and Hungary, among others. Its safe use, however, is dependent on the availability of a reliable reversal drug. Although widely used, there are concerns with the use of neostigmine for reversal. Arduan is a powerful competitive antagonist of acetylcholine, since it can bind pre- and postsynaptic (N1) receptors of the transmitters.