The FDAs Gastrointestinal Drugs Advisory Committee referred to the drugs efficacy as "modest", highlighting that the placebo brought relief on the primary outcome measure to 40–50% of women. Contraindications
Lotronexs prescribing information brochure states that alosetron should not be initiated in patients with constipation. Other contraindications are: history of chronic or severe constipation or sequelae from constipation; intestinal obstruction, stricture, toxic megacolon, gastrointestinal perforation, and/or adhesions, ischemic colitis, impaired intestinal circulation, thrombophlebitis, or hypercoagulable state; Crohns disease or ulcerative colitis; diverticulitis; severe hepatic impairment. Concomitant use of fluvoxamine is also contraindicated. Adverse effects
Alosetron was withdrawn in 2000 following the association of alosetron with serious life-threatening gastrointestinal adverse effects. The cumulative incidence of ischaemic colitis was 2 in 1000, while serious complications arising from constipation (obstruction, perforation, impaction, toxic megacolon, secondary colonic ischaemia, death) was 1 in 1000. A 1999 review performed by FDA medical officer John Senior, indicated that 27% of patients experienced constipation. The phase III trial reported constipation occurred in 30% and 3% of patients in the alosetron and placebo groups, respectively. It was cited as the most important reason for patients dropping out of the study. Mechanism of action
Alosetron has an antagonist action on the 5-HT3 receptors of the enteric nervous system of the gastrointestinal tract. While being a 5-HT3 antagonist like ondansetron, it is not classified or approved as an antiemetic.
The simplest one is the caloric reflex test, in which one ear canal is irrigated with warm or cold water or air. The temperature gradient provokes the stimulation of the horizontal semicircular canal and the consequent nystagmus. Nystagmus is often very commonly present with Chiari malformation. The resulting movement of the eyes may be recorded and quantified by a special device called an electronystagmograph (ENG), a form of electrooculography (an electrical method of measuring eye movements using external electrodes), or an even less invasive device called a videonystagmograph (VNG), a form of video-oculography (VOG) (a video-based method of measuring eye movements using external small cameras built into head masks), administered by an audiologist. Special swinging chairs with electrical controls can be used to induce rotatory nystagmus.Over the past forty years, objective eye-movement-recording techniques have been applied to the study of nystagmus, and the results have led to greater accuracy of measurement and understanding of the condition. Orthoptists may also use an optokinetic drum, or electrooculography or Frenzel goggles to assess a patients eye movements. Nystagmus can be caused by subsequent foveation of moving objects, pathology, sustained rotation or substance use.