Cyclizine

(Hong Kong--The Hong Kong Practitioner, December 2000, p. 601.) Between 40 and 70 percent of patients with advanced cancer suffer from significant nausea and vomiting. These symptoms may directly result from the cancer, might be caused by a secondary effect such as gastrointestinal blockage or raised intracranial pressure, or could represent treatment side effects. Nausea and vomiting are frequently multifactorial in origin and require a detailed history, physical examination and other investigations to identify the cause. Therapy aims to treat any reversible cause as well as to relieve symptoms. Dietary manipulation, relaxation therapy, guided imagery and distraction may be useful as complete or adjunct treatments. Nasogastric suction, gastrostomy and selective surgical interventions also may help to relieve symptoms in selected patients, but the primary management of nausea and vomiting depends on antiemetic medications. These medications should be started as early as possible, and the dosage should be titrated to optimize the effect. A combination of drugs with different actions may be more effective than high dosages of a single agent. Medication may need to be provided by suppository, parenterally or by other nonoral routes to ensure absorption. Antiemetic drugs act centrally, on the gastrointestinal system, or both to suppress symptoms. Drugs that act primarily on the central nervous system receptors or the vestibular system include butyrophenones (e.g., haloperidol), phenothiazines (e.g., prochlorperazine, chlorpromazine), antihistamines (e.g., cyclizine) and anticholinergics (e.g., hyoscine). Antiemetic drugs with direct effects on the gastrointestinal system include metoclopramide, domperidone and octreotide (an analog of somatostatin). Antagonists of 5-HT3 receptors (i.e., ondansetron and tropisetron) have both central and gastrointestinal effects but are very expensive. Specific medications should be selected to match the drug effect to the cause of the vomiting; side-effect profile; route, timing and form of administration; cost; and patient-specific factors. Each drug is briefly reviewed in the full article, which is available online at http://www.hkcfp.org.hk/journal.htm.

COPYRIGHT 2001 American Academy of Family Physicians
COPYRIGHT 2001 Gale Group