Developed by Solvay Pharmaceuticals, cilansetron is a 5-HT3 antagonist indicated for the treatment of diarrhoea-predominant irritable bowel syndrome (IBS). 5-HT(3) receptor antagonists such as cilansetron have been shown to affect gastrointestinal motility. With Phase III registration trials on cilansetron completed, Solvay filed for regulatory approval in Europe and the US in 2004. To ensure that cilansetron is only prescribed to patients with diarrhoea-predominant IBS, Solvay’s regulatory submission included an extensive appropriate use plan. In April 2005, however, Solvay received a “non-approvable” letter from the FDA and a request for additional data to support product registration in the US. Towards the end of 2005, the company announced that it had suspended registration of cilansetron in the US. Meanwhile, discussions continue with the UK’s MHRA about European marketing approval for cilansetron. In 2005, the MHRA also declined to approve cilansetron. Both the agencies requested additional clinical data to further assess the risk-benefit ratio of the compound. Despite the drug being rejected for approval, Solvay believed in the product and felt that the clinical data demonstrated important benefits for men and women suffering from diarrhoea-predominant IBS. However, taking into account the amount of clinical work requested and other business considerations, the company decided to end the development and regulatory activities for cilansetron. The clinical efficacy and safety of cilansetron was established in a series of clinical trials, including a large-scale international Phase III programme involving over 4,000 patients. Overall, results from these trials showed that cilansetron is significantly more effective than placebo in male and female patients with diarrhoea-predominant IBS, an important finding given the traditionally high placebo response rates seen in clinical trials of IBS drugs. Overall responder rates (adequate relief in at least 50% of weekly responses) for patients treated with cilansetron ranged from 52% to 61% compared with 37% to 46% for placebo recipients. The most common side effect of cilansetron is constipation, which is seen in 3-12% of subjects at 6 months. Ischemic colitis, a side effect associated with previous drugs of this class, has been seen in eight subjects (six women and two men) to date. All of these ischemic colitis events have been self-limited and did not require surgery. Because of its high degree of efficacy, the fact that it was well tolerated by the overwhelming majority of patients and that it showed efficacy in both genders, cilansetron represented a major advance in the treatment of irritable bowel syndrome with diarrhea predominance.

Itopride is a dopamine D2 receptor antagonist and inhibitor of acetylcholinesterase. It is indicated in the for the treatment of gastrointestinal symptoms caused by reduced gastrointestinal motility, such as functional non-ulcer dyspepsia (chronic gastritis), gastric fullness, rapid satiation, pain or discomfort in the upper abdomen, anorexia, heartburn, nausea, and vomiting. The drug is not approved in the USA or UK but is available in Japan and Western European countries.

Rociverine is the antispasmodic agent with balanced neurotropic and myotropic activity. The muscle-relaxant activity of rociverine is achieved by inhibiting the availability of Ca2+ at contraction site and not through an antiphosphodiesterasic mechanism, which might explain the absence of muscle-relaxant effects on the smooth musculature of the blood vessels. Rociverine did not differ statistically from the reference antispasmodic drug hyoscine butylbromide in premedication for endoscopy of the upper gastro-intestinal tract. No adverse effects were noted. Intrapartum administration of rociverine to nulliparous women may help to reduce the duration of the first stage of labor in a context of uniform labor management. Orally administered rociverine produced a dose-related reversal of the reserpine-induced detrusor hyperreflexia in anaesthetized rats. In experimental models rociverine was more effective than flavoxate. These results point to the usefulness of rociverine in the treatment of urinary bladder motility disorders.

Clebopride is a dopamine antagonist drug. It is used to treat functional gastrointestinal disorder such as nausea or vomiting. Unchanged parent drug was the most abundant compound in human urine. Major metabolites included the hydroxylation at benzyl group to yield carbinolamine and its further N-dealkylation product, and the piperidine ring hydroxylation/oxidation metabolite (a lactam).

Tiemonium (often used in a form of iodide or methylsulphate salt) is a muscarinic acetylcholine receptor antagonist, which is available in Asia (mainly Bangladesh) for the alleviation of muscle spasms of the intestine, biliary system, uterus and urinary bladder in gastrointestinal, biliary, urinary and gynecological diseases.

Bromopride is a dopamine D2 receptor blocker. Bromopride exerts is a gastrointestinal prokinetic exploited clinically for the management of motor disorders of the upper gastrointestinal tract, including functional dyspepsia, gastric stasis of various origins and emesis.

Caroverine is a spasmolytic drug used in tinnitus treatment improves mechanosensitivity and mechanotransduction phenomenon and otoneuroprotective agent. Caroverine acts as an N-type calcium channel blocker, competitive AMPA receptor antagonist, and non-competitive NMDA receptor antagonist. When excessive glutamate binds to NMDA receptors, the receptor opens and allows calcium and sodium to enter the neuron, abnormal levels of calcium disturbs ionic balance causing spontaneous depolarization state. Pathological spontaneous depolarization state is reversed back to physiological polarization state by antagonistic property of Caroverine.

Fentonium is an anticholinergic, antispasmodic and anti-ulcerogenic agent. It is quaternary analog of hyoscyamine, is a blocker of muscarinic activity and an allosteric blocker of α12βγε nicotinic receptors. It increases the spontaneous release of acetylcholine at the motor endplate without depolarizing the muscle or inhibiting cholinesterase activity. Fentonium inhibited transmitter release and depressed twitch without changing the responsiveness to noradrenaline or ATP. It is a K(+)-channel opener. Administration of fentonium bromide in rats receiving naloxone after chronic morphine treatment reduced the intensity of withdrawal signs such as increased defecation or micturition, salivation and wet-dog shakes, and elevated the nociceptive threshold values.

Mebeverine is an antispasmodic with a direct action on the smooth muscle of the gastrointestinal tract. The exact mechanism of action is not known, but multiple mechanisms, such as a decrease in ion channel permeabilities, blockade of noradrenaline reuptake, a local anesthetic effects, as well as weak anti-muscarinic and phosphodiesterase inhibitory effect might contribute to the local effects of Mebeverine. This medicine is used to treat symptoms of irritable bowel syndrome (IBS) and similar problems such as chronic irritable colon, spastic constipation, mucous colitis and spastic colitis. Most people will not have problems with Mebeverine, but some may get some side effects, such as: difficulty in breathing, swelling of face, neck, tongue or throat, skin rash, red itchy skin.

Drotaverine, an antispasmodic drug, is a synthetic derivative of the natural isoquinoline alkaloid of Papaver somniferum, papaverine. It inhibits cyclic-3',5'-nucleotide-phophodiesterase (PDE) enzymes with concentration-dependent specificity, in addition, it behaves as a L-type voltage- operated calcium channel (L-VOCC) blocker. Drotaverin also acts as a cytostatic compound for several human tumor cell lines. Drotaverine is an effective medicine to treat spasm or twitches of the smooth muscles in the stomach and heart. It is used to relieve pain caused due to irritable bowel syndrome, headache, menstrual periods, and is also used to relieve cervical spasm during labor.