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.

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is metabolized to metabolites M1 and M2 which are more active toward the monoamine transporters.The drug was withdrawn from the market because of clinical trial data indicating an increased risk of heart attack and stroke.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.

Cerivastatin (BAYCOL®) is a competitive inhibitor of HMG-CoA reductase, which is responsible for the conversion of 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) to mevalonate, a precursor of sterols, including cholesterol. The inhibition of cholesterol biosynthesis by cerivastatin reduces the level of cholesterol in hepatic cells, which stimulates the synthesis of low-density lipoprotein (LDL) receptors, thereby increasing the uptake of cellular LDL particles. The end result of these biochemical processes is a reduction of the plasma cholesterol concentration. On August 8, 2001 the U.S. Food and Drug Administration (FDA) announced that Bayer Pharmaceutical Division voluntarily withdrew BAYCOL® from the U.S. market, due to reports of fatal rhabdomyolysis, a severe adverse reaction from this cholesterol-lowering (lipid-lowering) product. It has also been withdrawn from the Canadian market.

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.

Stavudine is a nucleoside reverse transcriptase inhibitor (NRTI) with activity against Human Immunodeficiency Virus Type 1 (HIV-1). Stavudine is phosphorylated to active metabolites that compete for incorporation into viral DNA. They inhibit the HIV reverse transcriptase enzyme competitively and act as a chain terminator of DNA synthesis. The lack of a 3'-OH group in the incorporated nucleoside analogue prevents the formation of the 5' to 3' phosphodiester linkage essential for DNA chain elongation, and therefore, the viral DNA growth is terminated. Stavudine inhibits the activity of HIV-1 reverse transcriptase (RT) both by competing with the natural substrate dGTP and by its incorporation into viral DNA. Stavudine is used for the treatment of human immunovirus (HIV) infections. Stavudine is sold under the brand name Zerit among others.

Levalmodipine (S-amlodipine) is an active enantiomer of amlodipine, a calcium antagonist that inhibits the transmembrane influx of calcium ions into vascular smooth muscle and cardiac muscle. Experimental data suggest that S-amlodipine binds to both dihydropyridine and nondihydropyridine binding sites. The contractile processes of cardiac muscle and vascular smooth muscle are dependent upon the movement of extracellular calcium ions into these cells through specific ion channels. S-Amlodipine inhibits calcium ion influx across cell membranes selectively, with a greater effect on vascular smooth muscle cells than on cardiac muscle cells. Enantiomerically pure S-amlodipine is marketed in some countries worldwide, while racemate, containing active S-enantiomer an inactive R-enantiomer is marketed in the USA and indicated for the treatment of hypertension and coronary artery disease.

Nabilone is a synthetic cannabinoid approved under the brand name cesamet for treatment of severe nausea and vomiting associated with cancer chemotherapy. Nabilone is an orally active which, like other cannabinoids, has complex effects on the central nervous system (CNS). It has been suggested that the antiemetic effect of nabilone is caused by interaction with the cannabinoid receptor system, i.e. the CB (1) receptor, which has been discovered in neural tissues.

Sulfaphenazole is an oral antibiotic, which was used for the treatment of bacterial infections under the name Sulfabid. The drug was found to block folate synthesis in bacterias by inhibiting the enzyme dihydropteroate synthase. Sulfaphenazole is also known to inhibit CYP2C9 with high potency and specificity. Sulfabid is no longer marketed in the USA.

Sulfinpyrazone was approved by the U.S. Food and Drug Administration (FDA) on May 13, 1959. It was developed and marketed as Anturane® by Novartis. Sulfinpyrazone is an oral uricosuric agent (pyrazolone derivative) used to treat chronic or intermittent gouty arthritis. Sulfinpyrazone competitively inhibits the reabsorption of uric acid at the proximal convoluted tubule, thereby facilitating urinary excretion of uric acid and decreasing plasma urate concentrations. This is likely done through inhibition of the urate anion transporter (hURAT1) as well as the human organic anion transporter 4 (hOAT4). Sulfinpyrazone is not intended for the treatment of acute attacks because it lacks therapeutically useful analgesic and anti-inflammatory effects. Sulfinpyrazone and its sulfide metabolite possess COX inhibitory effects. Sulfinpyrazone has also been shown to be a UDP-glucuronsyltransferase inhibitor and a very potent CYP2C9 inhibitor. Sulfinpyrazone is also known to be a cystic fibrosis transmembrane conductance regulator (CFTR) inhibitor as well as an inhibitor of several multridrug resistance proteins (MRPs). Branded and generic forms of sulfinpyrazone have been discontinued in the US.

Troleandomycin (also known Triacetyl-oleandomycin and having brand name Tao) is a macrolide antibiotic which used to for the treat of infections of the upper and lower respiratory tract: such as tonsillitis, bronchitis, sinusitis, and pneumonia. However, the brand name Tao was discontinued. Troleandomycin acts by penetrating the bacterial cell membrane and reversibly binding to the 50 S subunit of bacterial ribosomes or near the "P" or donor site so that binding of tRNA (transfer RNA) to the donor site is blocked. Translocation of peptides from the "A" or acceptor site to the "P" or donor site is prevented, and subsequent protein synthesis is inhibited.