Methylnaltrexone bromide, (17s)- (methylnaltrexone bromide), a quaternary amine of the pure narcotic antagonist naltrexone, is a peripherally-acting selective mu-opioid antagonist. Methylnaltrexone antagonizes opioid binding at mu-opioid receptors, half-maximal inhibitory concentration (IC50) of 70 nM. It has a relatively lower affinity for κ-opioid receptors (IC50 575 nM), and it does not interact with δ-receptors or orphanin FQ receptors. Approved by FDA in the United States under the trade name Relistor, methylnaltrexone bromide is indicated for the treatment of opioid-induced constipation in patients with advanced illness who are receiving palliative care, when the response to laxative therapy has not been sufficient. Restricted ability to cross the blood-brain barrier allows methylnaltrexone bromide to function in tissues such as the gastrointestinal tract, decreasing the constipating effects of opioids without impacting opioid-mediated analgesic effects on the central nervous system.

Revaprazan (trade name Revanex) is a drug that reduces gastric acid secretion and is used for the treatment of gastritis and acid-related disease. It acts as an acid pump antagonist (potassium-competitive acid blocker) that reversibly inhibits H+, K+-ATPase by binding to the K+-binding site of the pump, thereby causing fewer side effects, compared with the irreversible proton pump inhibitors. Revaprazan is approved for use in Korea, but is not approved in Europe or the United States.

Casopitant (GW679769) is a novel substituted piperidine derivative that competitively binds with NK1 receptors. The full occupancy of the receptor by their piperidine compound inhibits its binding with tachykinin neurotransmitters, including SP. Casopitant, in a series of in vitro and in vivo experimentations, has exhibited a potent NK1 receptor antagonism. On 29 May 2008, GlaxoSmithKline announced the submission of a new drug application to the FDA for intravenous and oral formulations of casopitant mesylate. This drug was proposed for the prevention of chemotherapy-induced nausea and vomiting as an add-on therapy to the standard dual therapy of 5-HT3 receptor antagonists + dexamethasone. The submission also included a proposed indication for postoperative nausea and vomiting prevention. Rezonic™ is the proposed trade name for casopitant mesylate in the United States; Zunrisa™ is the proposed trade name for casopitant mesylate for GlaxoSmithKline’s global group of companies. In September 2009, GlaxoSmithKline decided to discontinue all regulatory filings for casopitant based on an estimate of the amount of additional safety data.

Fenpiverinium is a quaternary ammonium compound, it is an anticholinergic and antispasmodic agent. It is a constituent of Baralgin. The effects of the constituents of Baralgin (metamizole , fenpiverinium, and pitofenone ) on mechanical activity were studied in isolated human preparations of the upper urinary tract. Fenpiverinium blocked the increase in frequency of phasic-rhythmic contractions and the tonic tension development induced by acetylcholine. Fenpiverinium did influence neither spontaneous phasic activity nor activation by high potassium or norepinephrine. Fenpiverinium has exclusively anticholinergic properties. Fenpiverinium is a muscarinic acetylcholine receptor antagonist.

Ramosetron (INN) is a serotonin 5-HT3 receptor antagonist for the treatment of nausea, vomiting. And "diarrhea-predominant irritable bowel syndrome in males" (IBS-D). Ramosetron is licensed for use in India, Japan (Iribo) and selected Southeast Asian countries. In animal studies, ramosetron reduced defecation induced by corticotrophin-releasing hormone and had inhibitory effects on colonic nociception. In two randomized controlled studies including 957 patients with IBS-D, ramosetron increased monthly responder rates of patient-reported global assessment of IBS symptom relief compared with placebo. Ramosetron was also as effective as mebeverine in male patients with IBS-D. In a recent randomized controlled trial with 343 male patients with IBS-D, ramosetron has proved effective in improving stool consistency, relieving abdominal pain/discomfort, and improving health-related quality of life. Regarding safety, ramosetron is associated with a lower incidence of constipation compared with other 5-HT3 receptor antagonists and has not been associated with ischemic colitis.

Flupirtine is a triaminopyridine derivative having a chemical structure - 2-amino-3-ethoxy-carbonylamino-6-4-fluoro-benzylamino-pyridine. The basic molecule used for synthesis of flupirtine was 2, 6-dichoro 3-nitropyridine. It was first synthesized in 1980s in Germany and was marketed by Degussa Pharma. Flupirtine is a centrally acting, non-opioid analgesic that is available in a number of European countries for the treatment of a variety of pain states. The therapeutic benefits seen with flupirtine relate to its unique pharmacological properties. Flupirtine displays indirect NDMA receptor antagonism via activation of potassium channels and is the first representative of a pharmacological class denoted the 'selective neuronal potassium channel openers'. The generation of the M-current is facilitated by flupirtine via the opening of neuronal Kv7 potassium channels. The opening of these channels inhibits exaggerated neuronal action potential generation and controls neuronal excitability. Neuronal hyperexcitability is a physiological component of many pain states such as chronic pain, migraine and neurogenic pain.

Nomegestrol acetate (NOMAC) is a 19-norprogesterone derivative with high biological activity at the progesterone receptor, a weak anti-androgenic effect, but with no binding to estrogen, glucocorticoid or mineralocorticoid receptors. Nomegestrol has been developed by the Monaco-based company Théramex SAM (a Teva subsidiary). Nomegestrol acetate has been used successfully for the treatment of some gynaecological disorders (menstrual disturbances, dysmenorrhoea, premenstrual syndrome) and as a component of hormone replacement therapy in combination with estradiol for the relief of menopausal symptoms; it has been approved in Europe as monotherapy for the treatment of the menopausal syndrome, uterine diseases and menorrhagia, and in combination with an estrogen for the treatment of menopausal symptoms. Nomegestrol acetate in combination with estradiol is used as an oral contraceptive.

Raclopride is a salicylamide neuroleptic, that acts as a selective antagonist of D2 dopamine receptors both in vitro and in vivo. Tritium-labelled raclopride has properties that demonstrate its usefulness as a radioligand for the labelling of dopamine-D2 receptors : 3H-Raclopride has a high affinity for the rat and human dopamine-D2 receptors, the non-specific binding of 3H-raclopride is very low, not exceeding 5% of the total binding and the distribution of the 3H-raclopride binding sites in the brain closely correlates with the dopaminergic innervation. The binding of 3H-raclopride is blocked by dopamine-D2 agonists and antagonists, while the D1 agonist SKF 38393 and the Dl antagonist SCH 23390 have much less potency. The interaction of dopamine with 3H-raclopride binding results in a shallow competition curve, which suggests that 3H-raclopride, similar to other dopamine-D2 radioligands, labels both high and low agonist affinity states of the dopamine-D2 receptor. The in vivo receptor binding studies performed with 3H-raclopride also demonstrate its favorable properties as a dopamine-D2 receptor marker in vivo In contrast to some other compounds used as radioligands, raclopride enters the brain readily and binds with a low component of non-specific binding in all dopamine-rich brain areas. A saturation curve may be achieved in vivo binding studies since injections of increasing concentrations of 3H-raclopride appears to be saturated at concentrations above 25 mkCi (corresponding to approximately 5 nmol/kg). Raclopride antagonizes apomorphine-induced hyperactivity in the rat at low doses (ED50 = 130 nM/kg i.p.) but induces catalepsy only at much higher doses (ED50 = 27 mkM/kg i.p.). Radiolabelled raclopride has been used as a ligand for in vitro and in vivo autoradiography in rat and primate brains. Raclopride C 11 is used with positron emission tomography (PET) as a clinical research tool to determine dopamine type 2 (D 2) receptor density in the human brain under normal and pathological conditions. For example, raclopride C 11 used in PET studies has served to confirm the age-related decrease in striatal dopamine D2 receptor density, which may be associated with a decline in the motor as well as cognitive functions. In patients with Alzheimer's disease, raclopride C 11 may be used to examine neuroreceptor distribution and quantities, which may help in the analysis of degenerative alterations of neuron populations and neuroreceptor systems in patients with this disease. In Huntington's disease, in which degeneration of neostriatal interneurons occurs (postsynaptic to the dopaminergic input), specific binding of raclopride C 11 to D 2 receptors may serve as one of the parameters in predicting performance in cognitive tasks.

Zuclopenthixol is indicated the management of the manifestations of schizophrenia and other mental illnesses with disturbances in thinking, emotional reactions and behaviour. It is also used to treat the manic phase of manic depressive illness. Zuclopenthixol, a thioxanthene derivative, has high affinity for both dopamine D1 receptors and dopamine D2 receptors. Zuclopenthixol also has high affinity for α1-adrenergic and 5-HT2 receptors. Zuclopenthixol (CLOPIXOL®) is avavilable in the form of tablets and solution for intramuscular injections.

Alcuronium (diallylnortoxiferine) is a semi-synthetic substance prepared from C-toxiferine I a bis-quaternary alkaloid obtained from Strychnos toxifera. Alcuronium is a neuromuscular blocking (NMB) agent, alternatively referred to as a skeletal muscle relaxant. Alcuronium is used for endotracheal intubation and to produce muscle relaxation in general anesthesia during surgical procedures. The pharmacological action of alcuronium is readily reversed by neostigmine, and it produced little histamine release. The major disadvantage of alcuronium is that it elicits a vagolytic effect produced by a selective atropine-like blockade of cardiac muscarinic receptors.