Vinyl Chloride, a gas, is produced as a combustion product in tobacco smoke. Vinyl Chloride is used to produce polyvinyl chloride (PVC) and was workers exposed to vinyl chloride were at carcinogenic risk.

Telbivudine is an antiviral drug used in the treatment of hepatitis B infection. It is marketed by Swiss pharmaceutical company Novartis under the trade names Sebivo (Europe) and Tyzeka (United States). Clinical trials have shown it to be significantly more effective than lamivudine or adefovir, and less likely to cause resistance. Telbivudine is a synthetic thymidine nucleoside analogue; it is the L-isomer of thymidine. It is taken orally in a dose of 600 mg once daily with or without food. TYZEKA is the trade name for telbivudine, a synthetic thymidine nucleoside analogue with activity against hepatitis B virus (HBV). The chemical name for telbivudine is 1-((2S,4R,5S)-4-hydroxy-5-hydroxymethyltetrahydrofuran-2-y1)-5-methyl-1H-pyrimidine-2,4-dione, or 1-(2-deoxy-β-L-ribofuranosyl)-5-methyluracil. Telbivudine is a synthetic thymidine nucleoside analogue with activity against HBV DNA polymerase. It is phosphorylated by cellular kinases to the active triphosphate form, which has an intracellular half-life of 14 hours. Telbivudine 5'-triphosphate inhibits HBV DNA polymerase (reverse transcriptase) by competing with the natural substrate, thymidine 5'-triphosphate. Incorporation of telbivudine 5'-triphosphate into viral DNA causes DNA chain termination, resulting in inhibition of HBV replication. Telbivudine is an inhibitor of both HBV first strand (EC50 value = 1.3 ± 1.6 µM) and second strand synthesis (EC50 value = 0.2 ± 0.2 µM). Telbivudine 5'-triphosphate at concentrations up to 100 µM did not inhibit human cellular DNA polymerases α, β, or γ. No appreciable mitochondrial toxicity was observed in HepG2 cells treated with telbivudine at concentrations up to 10 µM.

Tegaserod (3‐(5‐methoxy‐1H‐indol‐3ylmethylene)‐N‐pentyl‐carbazimidamide), an aminoguanidine indole derivative of serotonin, is a selective partial agonist highly selective for 5‐HT4 receptor with an affinity constant in the nanomolar range. Tegaserod, by acting as an agonist at neuronal 5-HT4 receptors, triggers the release of further neurotransmitters such as calcitonin gene-related peptide from sensory neurons. The activation of 5-HT4 receptors in the gastrointestinal tract stimulates the peristaltic reflex and intestinal secretion, as well as inhibits visceral sensitivity. In vivo studies showed that tegaserod enhanced basal motor activity and normalized impaired motility throughout the gastrointestinal tract. Zelnorm® (tegaserod maleate) is indicated for the short-term treatment of women with irritable bowel syndrome (IBS) whose primary bowel symptom is constipation. In addition Zelnorm® is indicated for the treatment of patients less than 65 years of age with chronic idiopathic constipation.

CHOLINE is a basic constituent of lecithin that is found in many plants and animal organs. Choline was officially recognized as an essential nutrient by the Institute of Medicine in 1998.1 Its role in the body is complex. It is needed for neurotransmitter synthesis (acetylcholine), cell-membrane signaling (phospholipids), lipid transport (lipoproteins), and methyl-group metabolism (homocysteine reduction). It is the major dietary source of methyl groups via the synthesis of S-adenosylmethionine (AdoMet). At least 50 AdoMet-dependent reactions have been identified in mammals, and it is likely that the number is much higher. Choline is required to make the phospholipids phosphatidylcholine, lysophosphatidylcholine, choline plasmalogen, and sphingomyelin—essential components for all membranes. It plays important roles in brain and memory development in the fetus and appears to decrease the risk of the development of neural tube defects. The importance of choline in the diet extends into adulthood and old age. In a study of healthy adult subjects deprived of dietary choline, 77% of the men and 80% of the postmenopausal women developed signs of subclinical organ dysfunction (fatty liver or muscle damage). Less than half of premenopausal women developed such signs. Ten percent of the subjects studied developed fatty liver, muscle damage, or both when they consumed the Adequate Intake (AI) of choline. The damage was reversed when they consumed a high-choline diet. Plasma choline concentration has been found to vary in response to diet, decreasing approximately 30 percent in humans fed a choline-deficient diet for 3 weeks. Based on estimated dietary intakes and studies reporting liver damage with lower choline intakes, the Institute of Medicine, Food and Nutrition Board set the AI for choline at 425 milligrams/per day for women aged 19 and older, and 550 milligrams/per day for men aged 19 and older.

Rofecoxib is a nonsteroidal anti-inflammatory drug which selectively inhibits COX-2 and subsequent prostaglandin synthesis. The drug was developed by Merk and approved by FDA in 1999 for relief of signs and symptoms of arthritis, acute pain in adults, and painful menstrual cycles under the name Vioxx. Later on Merck voluntarily withdrawn Vioxx from the market due to safety concerns (high risk of heart attack and stroke).

Rapacuronium bromide (RAPLON), a nondepolarizing neuromuscular blocking agent, is a negative allosteric modulator of muscarinic acetylcholine receptors. Rapacuronium bromide is indicated as an adjunct to general anesthesia to facilitate tracheal intubation and to provide skeletal muscle relaxation during surgical procedures. There were no specific pharmacokinetic studies conducted to examine the drug-drug interactions of RAPLON. Due to the risk of fatal bronchospasm, it was withdrawn from the United States market less than 2 years after its FDA approval.

Mequinol (mequinol is 4-hydroxyanisole) is an active ingredient in topical drugs used for skin depigmentation. The mechanism of action of mequinol is unknown. Although mequinol is a substrate for the enzyme tyrosinase and acts as a competitive inhibitor of the formation of melanin precursors, the clinical significance of these findings is unknown.

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.

Alatrofloxacin is a fluoroquinolone antibiotic developed as a mesylate salt and was sold under brand name Trovan, but was withdrawn from the U.S. market in 2001. Trovan was indicated for the treatment of patients initiating therapy in in-patient health care facilities (i.e., hospitals and long term nursing care facilities) with serious, life- or limb-threatening infections caused by susceptible strains of the designated microorganisms in the conditions listed below. Nosocomial pneumonia caused by Escherichia coli, Pseudomonas aeruginosa, Haemophilus influenzae, or Staphylococcus aureus. Community acquired pneumonia caused by Streptococcus pneumoniae, Haemophilus influenzae, Klebsiella pneumoniae, Staphylococcus aureus. Complicated intra-abdominal infections, including post-surgical infections caused by Escherichia coli. Gynecologic and pelvic infections including endomyometritis, parametritis, septic abortion and post-partum infections caused by Escherichia coli, Bacteroides fragilis, viridans group streptococci, Enterococcus faecalis. Complicated skin and skin structure infections, including diabetic foot infections, caused by Staphylococcus aureus, Streptococcus agalactiae, Pseudomonas aeruginosa, Enterococcus faecalis, Escherichia coli, or Proteus mirabilis. After intravenous administration, alatrofloxacin is rapidly converted to trovafloxacin, which is responsible for therapeutic effect. Plasma concentrations of alatrofloxacin are below quantifiable levels within 5 to 10 minutes of completion of a 1 hour infusion.

Subitramine is a potent inhibitor of monoamines (serotonin, dopamine, noradrenaline) reuptake that was approved by FDA for the treatmen of obesity. Sibutramine is metabolized to metabolites M1 and M2 which are more active toward the monoamine transporters.The drug was withdrawn from the market because of clinical trial data indicating an increased risk of heart attack and stroke. It was sold under a variety of brand names including Reductil, Meridia and Sibutrex.