Summary Opioid-induced gastrointestinal side effects are bothersome yet often manageable in patients receiving palliative care. Although it is often considered imprudent to treat the side effects of a drug with additional drugs, it is appropriate practice considering the desirability of adequate pain and symptom management. When an opioid is to be started, a thorough history of exposure to the agent, side effects experienced, as well as baseline bowel habits must be performed. By anticipating side effects and having a sound understanding of the pathophysiologic mechanisms by which opioids may cause nausea and constipation, the practitioner may confidently select the most appropriate agents to alleviate these symptoms based on that drug's known mechanism of action. Management of opioid-induced nausea must first be addressed with a decision for prophylaxis or to treat if and when the symptom becomes apparent. Metoclopramide or haloperidol may be considered first line for this indication at stated dosages. Therapy may be begun at the same time as opioid therapy, with anticipated duration of 2-3 days. For persons who have experienced opioid-induced nausea in the past, addition of a benzodiazepine, namely, lorazepam, should be considered. Treatment of opioid-induced nausea should be addressed with metoclopramide or a dopamine antagonist such as haloperidol. Monitoring for dose-limiting side effects should continue throughout therapy. Constipation should be managed systematically with a planned schedule of interventions before starting an opioid. The protocol may be site or practitioner specific and should be adhered to judiciously. Heightened awareness of side effects when managing pain with opioids in palliative care will greatly improve the quality of treatment that patients receive. Drugs for Treating Nausea in Palliative Care Drug Class Mechanism of Action Nausea Response Butyrophenones (haloperidol, droperidol) D2 blockade in CTZ Chemical irritation, visceral Phenothiazines and derivatives (chlorpromazine, prochlorperazine, thiethylperazine) D2 blockade in CTZ and gastrointestinal tract Vestibular Antihistamines (cyclizine, diphenhydramine, hydroxyzine, meclizine, promethazine) H1 blockade in vomiting center and vestibular apparatus Vestibular Anticholinergic agents (hyoscine, scopolamine) Muscarinic blockade in vomiting center and gastrointestinal tract Vestibular Serotonin antagonists (dolasetron, granisetron, ondansetron) 5-HT3 blockade in gastrointestinal tract and CTZ Gastric stasis Prokinetic agents (metoclopramide) D2 blockade in gastrointestinal tract and CTZ; 5-HT4 stimulation in gastrointestinal tract; 5-HT3 blockade in CTZ and gastrointestinal tract (high dosages) Gastric stasis Benzodiazepines (lorazepam) GABA agonist Anticipatory nausea CTZ = chemoreceptor trigger zone; 5-HT = serotonin; GABA = gamma-aminobutyric acid. Drugs for Treating Constipation in Palliative Care Drug General Mechanism Uses Softening agents (docusate) Stool-softening surfactant Coadministration with stimulant laxative; can be sole modality for patients who maintain adequate peristalsis Stimulants (bisacodyl, casanthranol, senna) Stimulant laxative Prophylaxis or treatment; may be used with stool softener Osmotics (glycerin suppositories, lactulose, mannitol, polyethylene glycol, sorbitol) Osmotic effect Prophylaxis or treatment; may be used with stool softener Saline (magnesium citrate, magnesium hydroxide, magnesium sulfate, sodium phosphates) Osmotic ion gradient Prophylaxis or treatment; may be used with stool softener Opioid antagonists (nalmefene, naloxone) Opioid receptor antagonists in gastrointestinal tract Prophylaxis; may be used with stool softener Lubricant (mineral oil) Softens fecal contents Softens fecal contents Ann's NOTE: Also see section under Relevant Studies called Non-Toxic methods for reducing unwanted effecgts. Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.