Niacin (also known as vitamin B3 and nicotinic acid) is bio converted to nicotinamide which is further converted to nicotinamide adenine dinucleotide (NAD+) and the hydride equivalent (NADH) which are coenzymes necessary for tissue metabolism, lipid metabolism, and glycogenolysis. Niacin (but not nicotinamide) in gram doses reduces LDL-C, Apo B, Lp(a), TG, and TC, and increases HDL-C. The increase in HDL-C is associated with an increase in apolipoprotein A-I (Apo A-I) and a shift in the distribution of HDL subfractions. These shifts include an increase in the HDL2:HDL3 ratio, and an elevation in lipoprotein A-I (Lp A-I, an HDL-C particle containing only Apo A-I). The mechanism by which niacin alters lipid profiles is not completely understood and may involve several actions, including partial inhibition of release of free fatty acids from adipose tissue, and increased lipoprotein lipase activity (which may increase the rate of chylomicron triglyceride removal from plasma). Niacin decreases the rate of hepatic synthesis of VLDL-C and LDL-C, and does not appear to affect fecal excretion of fats, sterols, or bile acids. As an adjunct to diet, the efficacy of niacin and lovastatin in improving lipid profiles (either individually, or in combination with each other, or niacin in combination with other statins) for the treatment of dyslipidemia has been well documented. The effect of combined therapy with niacin and lovastatin on cardiovascular morbidity and mortality has not been determined. In addition, preliminary reports suggest that niacin causes favorable LDL particle size transformations, although the clinical relevance of this effect is not yet clear. April 15, 2016: Based on several large cardiovascular outcome trials including AIM-HIGH, ACCORD, and HPS2-THRIVE, the FDA decided that "scientific evidence no longer supports the conclusion that a drug-induced reduction in triglyceride levels and/or increase in HDL-cholesterol levels in statin-treated patients results in a reduction in the risk of cardiovascular events" Consistent with this conclusion, the FDA has determined that the benefits of niacin ER tablets for coadministration with statins no longer outweigh the risks, and the approval for this indication should be withdrawn.

Cholecalciferol (/ˌkoʊləkælˈsɪfərɒl/) (vitamin D3) is one of the five forms of vitamin D. Cholecalciferol is a steroid hormone that has long been known for its important role in regulating body levels of calcium and phosphorus, in mineralization of bone, and for the assimilation of Vitamin A. The classical manifestation of vitamin D deficiency is rickets, which is seen in children and results in bony deformities including bowed long bones. Most people meet at least some of their vitamin D needs through exposure to sunlight. Ultraviolet (UV) B radiation with a wavelength of 290–320 nanometers penetrates uncovered skin and converts cutaneous 7-dehydrocholesterol to previtamin D3, which in turn becomes vitamin D3. In supplements and fortified foods, vitamin D is available in two forms, D2 (ergocalciferol) and D3 (cholecalciferol) that differ chemically only in their side-chain structure. Vitamin D2 is manufactured by the UV irradiation of ergosterol in yeast, and vitamin D3 is manufactured by the irradiation of 7-dehydrocholesterol from lanolin and the chemical conversion of cholesterol. The two forms have traditionally been regarded as equivalent based on their ability to cure rickets and, indeed, most steps involved in the metabolism and actions of vitamin D2 and vitamin D3 are identical. Both forms (as well as vitamin D in foods and from cutaneous synthesis) effectively raise serum 25(OH) D levels. Firm conclusions about any different effects of these two forms of vitamin D cannot be drawn. However, it appears that at nutritional doses, vitamins D2 and D3 are equivalent, but at high doses, vitamin D2 is less potent. The American Academy of Pediatrics (AAP) recommends that exclusively and partially breastfed infants receive supplements of 400 IU/day of vitamin D shortly after birth and continue to receive these supplements until they are weaned and consume ≥1,000 mL/day of vitamin D-fortified formula or whole milk. Cholecalciferol is used in diet supplementary to treat Vitamin D Deficiency. Cholecalciferol is inactive: it is converted to its active form by two hydroxylations: the first in the liver, the second in the kidney, to form calcitriol, whose action is mediated by the vitamin D receptor, a nuclear receptor which regulates the synthesis of hundreds of enzymes and is present in virtually every cell in the body. Calcitriol increases the serum calcium concentrations by increasing GI absorption of phosphorus and calcium, increasing osteoclastic resorption, and increasing distal renal tubular reabsorption of calcium. Calcitriol appears to promote intestinal absorption of calcium through binding to the vitamin D receptor in the mucosal cytoplasm of the intestine. Subsequently, calcium is absorbed through formation of a calcium-binding protein.

Pimilprost (SM-10902) and its free acid, SM-10906 are new stable 3-oxa-methano prostaglandin (PG) I1 analogs, SM-10902 is a prodrug of SM-10906. SM-10906, but not SM-10902 was demonstrated to be an agonist for IP receptors. SM-10906 was shown to exert its anti-platelet and vasodilatory activities through the increase of the cAMP level. Pimilprost was being developed by Dainippon Sumitomo Pharma (formerly Sumitomo Pharmaceuticals) in Japan for the treatment of skin ulcers. In Japan, an NDA was filed for pimilprost and was awaiting registration. However, development appears to have been discontinued.

Naluzotan (PRX-00023), a small molecule, non-azapirone, dual serotonin (5-HT)1A receptor agonist and sigma-1 receptor antagonist, is under development with Proximagen for the treatment of epilepsy. In previous clinical trials, the compound was shown to be safe and well-tolerated in over 400 patients. Epilepsy patients with localisation-related epilepsy have reduced 5-HT1a receptor binding as indicated by positron emission tomography (PET scan). It is thought that by increasing neurotransmitter activity at 5-HT1a receptor sites, seizure incidence and severity may be decreased.

Naronapride (ATI-7505), an orally administered, cisapride analogue and serotonin4 (5HT4) receptor agonist, is being developed by Renexxion for the treatment of multiple gastrointestinal disorders. Sinovant is initially developing naronapride for the treatment of irritable bowel syndrome – constipation (IBS-C), a disease that affects millions of Chinese patients and for which few effective treatment options are available. Naronapride has been evaluated in over 900 subjects in multiple randomized controlled clinical studies and has demonstrated promising results in patients with gastroesophageal reflux disease (GERD), erosive esophagitis (EE), and chronic idiopathic constipation (CIC). Naronapride’s low systemic absorption and high specificity for 5HT4 and D2 receptors is thought to improve its safety and tolerability profile relative to other members of the class.