ATI PHARM Gastrointestinal System

A nurse is planning care for a client who is receiving chemotherapy and has a new prescription for ondansetron. Which of the following actions should the nurse plan to take? (Select all that apply). A. Infuse the drug 30 min prior to chemotherapy. B. Administer the drug when the client reports nausea. C. Infuse the drug slowly over 15 min. D. Administer the drug immediately following chemotherapy. E. Repeat the dose 4 hr after chemotherapy.

A, C, E Infuse the drug 30 min prior to chemotherapy is correct. The nurse should administer IV ondansetron, a serotonin antagonist, 30 min prior to chemotherapy to prevent chemotherapy-induced nausea and vomiting. When treating radiation-induced nausea and vomiting, the nurse should give the drug orally 1 to 2 hr prior to radiation therapy and again every 8 hr. Administer the drug when the client reports nausea is incorrect. Ondansetron prevents nausea and vomiting from chemotherapy, radiation therapy, and anesthesia. The nurse should not wait until the client reports nausea to administer the drug. Infuse the drug slowly over 15 min is correct. The nurse should infuse ondansetron slowly over 15 min to prevent chemotherapy-induced nausea. Administer the drug immediately following chemotherapy is incorrect. Administering ondansetron immediately following chemotherapy might not allow enough time for the drug to exert its antiemetic actions before the client begins to feel chemotherapy-induced nausea. Repeat the dose 4 hr after chemotherapy is correct. For maximum effectiveness, the nurse should administer ondansetron 4 hr after chemotherapy, and again 8 hr after chemotherapy. When treating anesthesia-induced nausea and vomiting, the nurse can give the drug 1 hr before anesthesia induction.

A nurse is planning teaching for a client who has been prescribed loperamide to treat diarrhea. Which of the following statements should the nurse plan to include? A. "Avoid driving or activities requiring alertness." B. "If you miss a dose, double the next dose." C. "Rinsing the mouth with alcohol-based mouthwash can reduce dryness." D. "Having one glass of wine each night can improve medication effectiveness."

A. "Avoid driving or activities requiring alertness." --Loperamide can cause drowsiness and dizziness. The client should avoid driving or activities requiring alertness while taking the drug. B. --If the client misses a dose, they should not take skipped doses or double a dose. The client should continue the drug as prescribed, either taking it at timed intervals or with each incidence of diarrhea. C. --For dry mouth, the nurse should instruct the client to use oral rinses, sugarless gum, or candy for relief. Alcohol-based mouthwashes can have more of a drying effect than special oral rinses designed for dry mouth. D. --The client should avoid alcohol consumption while taking loperamide as it has the same CNS depressant effect as the drug. The client should also avoid using histamines, sedatives, or opioid analgesics while taking loperamide for this reason.

A nurse is teaching a client who has a new prescription for sulfasalazine. Which of the following statements should the nurse make? A. "Use sunscreen and protective clothing while taking sulfasalazine to prevent sunburn." B. "The medication can stain your contact lenses green." C. "The medication can color your urine dark brown." D. "Take an iron supplement when you take sulfasalazine to prevent anemia."

A. "Use sunscreen and protective clothing while taking sulfasalazine to prevent sunburn." --Photosensitivity is a possible adverse effect of sulfasalazine that makes the skin sensitive to light. The nurse should instruct the client to wear sunscreen and protective clothing when outdoors to prevent burning. B. --can stain contact lenses a YELLOW color C. --can color urine ORANGE-YELLOW D. --Interacts with iron and folic acid supplements, which will reduce absorption. Should take these supplements separately from sulfasalazine

A nurse is caring for a client who is taking allopurinol to treat gout and has a new prescription for azathioprine to treat ulcerative colitis. For which of the following reasons should the nurse clarify these prescriptions with the provider? A. Allopurinol delays the conversion of azathioprine and can lead to toxicity. B. Azathioprine increases the effectiveness of allopurinol. C. Allopurinol increases the metabolism of azathioprine and can require an increased dosage. D. Azathioprine decreases the effectiveness of allopurinol.

A. Allopurinol delays the conversion of azathioprine and can lead to toxicity. Allopurinol delays the conversion of azathioprine to an inactive form and can lead to toxicity. If used concurrently, the dose of azathioprine must be reduced. B. --Azathioprine does not increase the effectiveness of allopurinol. It can increase the risk of bone marrow suppression, which is an adverse effect of allopurinol. C. --Allopurinol decreases the rate of metabolism of azathioprine, which can cause the drug levels to build up in the body. If used concurrently, the dose of azathioprine must be reduced. D. --Azathioprine does not decrease the effectiveness of allopurinol.

A nurse is assessing a client who was administered ondansetron IV 1 hour ago. Which of the following findings should the nurse recognize as an adverse effect of this drug? A. Dizziness B. Bradycardia C. Tardive dyskinesia D. Dyspepsia

A. Dizziness Dizziness and lightheadedness are the most common adverse effects of ondansetron. B. --Torsade De Pointes, a form of tachycardia, is a potential adverse effect of ondansetron, not bradycardia. C. --Tardive dyskinesia is an adverse effect of metoclopramide. D. --Dyspepsia is an adverse effect of misoprostol.

A nurse is teaching a client who has a new prescription for methotrexate. The nurse should instruct the client to monitor for manifestations of which of the following conditions? A. Gout B. Constipation C. Insomnia D. Hirsutism

A. Gout An adverse effect of methotrexate is hyperuricemia, which causes gout. The nurse should instruct the client to drink plenty of fluids to minimize this effect, and to report edema or pain in the joints. B. --An adverse effect of methotrexate is diarrhea, not constipation. The nurse should instruct the client to monitor for diarrhea as well as bloody stools. C. --An adverse effect of methotrexate is drowsiness, not insomnia. The nurse should also warn the client that methotrexate can cause seizures. D. --An adverse effect of methotrexate is alopecia, not hirsutism. The nurse should inform the client about possible hair loss and assist the client with coping strategies.

A nurse should recognize that diphenoxylate/atropine should be used with caution for a client who has which of the following conditions? A. Inflammatory bowel disease B. Thrombophlebitis C. Agranulocytosis D. Immunization with a live virus vaccine within the last 6 weeks

A. Inflammatory bowel disease --Diphenoxylate is an opioid, which can cause the severe complication of toxic megacolon in clients who have inflammatory bowel disease. The nurse should have the client monitor the consistency and frequency of stools throughout therapy. B. --Clients who have thrombophlebitis can take diphenoxylate/atropine, an opioid antidiarrheal combination. Thrombophlebitis is a contraindication for the use of alosetron, another GI-system drug. C. --Clients who have agranulocytosis can take diphenoxylate/atropine, an opioid antidiarrheal combination. Agranulocytosis is a potential adverse drug reaction of sulfasalazine, another GI-system drug, and the drug should be used with caution for clients who have existing blood dyscrasias. D. --Clients who have had an immunization with a live virus vaccine within the last 6 weeks can take diphenoxylate/atropine, an opioid antidiarrheal combination. For clients who have recently received a live virus vaccine, azathioprine can reduce the antibody response and increase the risk of adverse reactions.

A nurse is caring for an older adult client who has renal impairment and a new prescription for cimetidine. The nurse should instruct the client to report which of the following manifestations? A. Lethargy B. Cellulitis C. Dry mouth D. Myalgia

A. Lethargy Cimetidine is a histamine2 receptor antagonist, which can potentially cross the blood-brain barrier. Older adult clients who have kidney impairments are at risk for central nervous system (CNS) effects such as lethargy, depression, confusion, and seizures. The nurse should instruct the client to report these manifestations to their provider. B. --Cimetidine, a histamine2 receptor antagonist, is unlikely to cause cellulitis. It can, however, cause other integumentary manifestations, such as rash, alopecia, and Stevens-Johnson syndrome. C. --Cimetidine, a histamine2 receptor antagonist, is unlikely to cause dry mouth. It can, however, cause other adverse GI effects, such as fungal overgrowth in the stomach and mild diarrhea. D. --Cimetidine, a histamine2 receptor antagonist, is unlikely to cause myalgia. It can, however, exacerbate joint pain in clients who have arthritis.

A nurse is caring for a client who is taking lubiprostone. The nurse should tell the client that lubiprostone can cause which of the following adverse drug reactions? A. Nausea B. Constipation C. Urinary retention D. Sore throat

A. Nausea Lubiprostone, a chloride channel activator, can cause nausea. Clients who develop this effect do not need to discontinue the drug but should take it with food and water to minimize GI upset. B. --Lubiprostone, a chloride channel activator, increases peristalsis and activates the chloride channels in the intestinal wall, which then increases the secretion of sodium and water. These actions treat constipation and can cause diarrhea. C. --Lubiprostone, a chloride channel activator, is unlikely to cause or worsen urinary retention. Dimenhydrinate, an antihistamine, is a GI-system drug that can cause urinary retention. D. --Lubiprostone, a chloride channel activator, is unlikely to cause or worsen a sore throat or respiratory infection. Sulfasalazine is a GI-system drug that can cause agranulocytosis, which could cause or worsen a sore throat.

A nurse is caring for a client who has a prescription for alosetron. The nurse should recognize that alosetron therapy is effective when the client reports which of the following? A. One formed stool per day B. Urination without burning C. Cessation of nausea or vomiting D. Reduced GI reflux effects

A. One formed stool per day Alosetron, a serotonin 5-HT3 receptor antagonist, treats the diarrhea and pain of severe irritable bowel syndrome. One formed stool per day indicates effective therapy. B. --Alosetron, a serotonin 5-HT3 receptor antagonist, is unlikely to improve burning or pain with urination. It can, however, cause urinary frequency. C. --Alosetron, a serotonin 5-HT3 receptor antagonist, is unlikely to affect nausea and vomiting. Ondansetron is a GI-system drug that treats nausea and vomiting. D. --Alosetron, a serotonin 5-HT3 receptor antagonist, is unlikely to affect gastrointestinal reflux. Metoclopramide is a GI-system drug that treats GERD.

A nurse is caring for a male client who asks the nurse about taking alosetron for irritable bowel syndrome with diarrhea (IBS-D) lasting 3 months. Which of the following information should the nurse provide the client about alosetron? A. The drug is prescribed to female clients who have IBS-D lasting more than 6 months. B. The drug is prescribed to clients who have chronic diarrhea lasting more than 12 months. C. The drug is most beneficial for male clients who have inflammatory bowel disease. D. The drug is most beneficial in treating clients who have constipation-predominant IBS (IBS-C).

A. The drug is prescribed to female clients who have IBS-D lasting more than 6 months. --Alosetron is approved only to be prescribed to females who have IBS-D lasting 6 months or longer that has not been controlled by conventional treatment. B. --Alosetron can be prescribed to clients who have certain types of chronic diarrhea caused by IBS, but it is not prescribed to treat all causes of chronic diarrhea. Furthermore, it can be prescribed sooner than 12 months. C. --Alosetron is not prescribed to treat inflammatory bowel disease. 5-aminosalicylate medications are one class of drugs used to treat this disorder. D. --Alosetron is approved only to be prescribed to women who have IBS-D, not IBS-C.

A nurse is administering sulfasalazine to a client. Which of the following data should the nurse collect to help identify an adverse drug reaction? (Select all that apply). A. Level of consciousness B. Skin integrity C. Temperature D. Urine output E. CBC

B, C, E -- Level of consciousness is incorrect. Sulfasalazine, a 5-aminosalicylate, is unlikely to affect level of consciousness. Metoclopramide, a dopamine antagonist, is a GI-system drug that can cause sedation. Skin integrity is correct. Sulfasalazine can cause a skin rash, so the nurse should check the client's skin for rashes. The drug can also cause nausea. If the client reports nausea, the nurse should suggest taking the drug with food or water. Temperature is correct. Sulfasalazine can cause a fever, so the nurse should check the client's temperature and treat fever with an antipyretic. Urine output is incorrect. Sulfasalazine is unlikely to affect urine output, although it can cause an orange-yellow discoloration of urine and skin. CBC is correct. Sulfasalazine can cause hematologic disorders, such as agranulocytosis and hemolytic and macrocytic anemia. The nurse should check the client's CBC periodically during therapy and tell the client to report sore throat or fatigue.

A nurse is caring for a client who has peptic ulcer disease. The nurse should monitor the client's phosphorus levels when administering which of the following drugs? A. Omeprazole B. Aluminum hydroxide C. Sucralfate D. Ranitidine

B. Aluminum hydroxide --Antacids that contain aluminum, such as aluminum hydroxide, can cause hypophosphatemia because of aluminum's ability to bind with phosphate and decrease its absorption. The nurse should monitor the client's phosphorus levels while administering this drug. A. --Administering omeprazole, a proton pump inhibitor, does not require monitoring of phosphorus levels. However, long-term therapy with the drug can cause bone loss, so it requires monitoring of bone density. C. --Administering sucralfate, a mucosal protectant, does not require monitoring of phosphorus levels. However, sucralfate therapy does require monitoring of bowel function. D. --Administering famotidine, a histamine2-receptor antagonist, does not require monitoring of phosphorus levels. However, famotidine therapy does require monitoring of the client's complete blood count periodically during therapy because it can cause anemia.

A nurse should recognize that sulfasalazine is contraindicated for clients who have which of the following conditions? A. Pancreatitis B. Aspirin sensitivity C. Bronchitis D. GERD

B. Aspirin sensitivity Any sensitivity to salicylates, sulfonamides, or trimethoprim is a contraindication for the use of sulfasalazine, a 5-aminosalicylate. This is because intestinal bacteria metabolize the drug into 5-aminosalicylic acid, a salicylate. Aspirin is also a salicylate. A. --Clients who have pancreatitis may take sulfasalazine, a 5-aminosalicylate. Pancreatitis is a potential adverse drug reaction of azathioprine, another GI-system drug. C. --Clients who have bronchitis may take sulfasalazine, a 5-aminosalicylate. However, this drug is contraindicated for clients who have an intestinal obstruction. D. --Clients who have GERD may take sulfasalazine, a 5-aminosalicylate. However, this drug is contraindicated for clients who have a bowel obstruction.

A nurse is reviewing the medical record of a client who has a new prescription for ranitidine. The nurse should recognize that which of the following drugs interacts with ranitidine? A. Phenobarbital sodium B. Ketoconazole C. Lisinopril D. Hydrochlorothiazide

B. Ketoconazole Famotidine reduces the absorption of ketoconazole. A. --Phenobarbital sodium does not interact with famotidine. However, it interacts with several types of drugs, including anticoagulants, oral contraceptives, and anticonvulsants. C. --Lisinopril does not interact with famotidine. However, lisinopril interacts with lithium carbonate and can cause lithium toxicity. D. --Hydrochlorothiazide does not interact with famotidine. However, it acts by promoting potassium loss and increases the risk of digoxin toxicity.

A nurse is providing teaching to a client who has a new prescription for omeprazole to treat a duodenal ulcer. Which of the following instructions should the nurse include? A. Take the drug with food B. Swallow the capsules whole C. Dissolve the tablets in water D. Take the drug at bedtime

B. Swallow the capsules whole Omeprazole, a proton pump inhibitor, is unstable in stomach acid. The nurse should instruct the client to swallow the capsules or tablets whole and not to crush or chew the capsules or tablets. A. --Food can reduce the absorption of omeprazole, a proton pump inhibitor. Clients should take omeprazole prior to meals. C. --Omeprazole, a proton pump inhibitor, is available in delayed-release tablets, capsules, or powder for oral suspension. If taking the tablet formulation, the client should swallow them whole because gastric acid can decrease the effectiveness of the medication. D. --Omeprazole, a proton pump inhibitor, decreases the secretion of gastric acid. It is most effective when clients take it in the morning prior to the first meal of the day.

A nurse is providing teaching to a client who has a new prescription for dimenhydrinate to prevent motion sickness. Which of the following instructions should the nurse include? (Select all that apply). A. Sit upright for 30 minutes after taking the drug B. Avoid antacids C. Take the drug 30 to 60 minutes before activities that trigger nausea D. Avoid activities that require alertness E. Increase fluid and fiber intake

C, D, E Sit upright for 30 min after taking the drug is incorrect. Dimenhydrinate, an antihistamine, is unlikely to cause esophagitis, so this precaution is unnecessary. Alendronate, a bisphosphonate that treats osteoporosis, is a drug that requires sitting upright for 30 min after taking it because it can cause esophagitis. Avoid antacids is incorrect. Dimenhydrinate does not interact specifically with antacids. Antacids can decrease the absorption of ranitidine, another GI-system drug. Take the drug 30 to 60 min before activities that trigger nausea is correct. The nurse should instruct the client to take dimenhydrinate 30 to 60 min before activities that trigger nausea, and again before meals and at bedtime. Avoid activities that require alertness is correct. Dimenhydrinate can cause sedation. The nurse should instruct the client to avoid activities that require alertness. Increase fluid and fiber intake is correct. Dimenhydrinate can cause anticholinergic effects, such as dry mouth and constipation. The nurse should instruct the client to increase activity level, and fluid and fiber intake.

A nurse is providing teaching to a client who is about to start taking psyllium to treat constipation. Which of the following instructions should the nurse include? (Select all that apply). A. Expect results in 6-12 hours B. Urinate every 4 hours C. Take the drug with at least 8 oz (237 mL) of fluid D. Avoid activities that require alertness E. Increase fluid and fiber intake

C, E Expect results in 6 to 12 hr is incorrect. Psyllium, a fiber supplement, typically results in soft, formed bowel movements 1 to 3 days after beginning therapy. Urinate every 4 hr is incorrect. Psyllium is unlikely to cause urinary retention. Atropine can cause anticholinergic effects, such as urinary retention, and can require scheduled urination to help prevent this effect. Take the drug with at least 8 oz (237 mL) of fluid is correct. To prevent esophageal obstruction, clients should take psyllium with at least 8 oz of fluid; and after mixing the powdered form, clients should drink it immediately. Avoid activities that require alertness is incorrect. Psyllium is unlikely to cause sedation or dizziness. Prochlorperazine is a GI-system drug that can cause sedation and requires avoiding activities that require alertness. Increase fluid and fiber intake is correct. The nurse should tell the client to increase activity, fluid intake, and fiber intake, and to keep track of bowel function.

A nurse should recognize that misoprostol is contraindicated for a client who has which of the following conditions? A. A seizure disorder B. Rheumatoid arthritis C. A positive pregnancy test D. Heart failure

C. A positive pregnancy test --Misoprostol, a prostaglandin E1 analog, is a teratogenic drug. It can cause uterine contractions and induce spontaneous abortion; therefore, providers must confirm that clients are not pregnant before prescribing the drug; and clients who take misoprostol must use contraception. A. --Clients who have a seizure disorder can take misoprostol, a prostaglandin E1 analog. Drugs that contain caffeine are contraindicated for clients who have a seizure disorder. B. --Clients who have rheumatoid arthritis can take misoprostol, a prostaglandin E1 analog, especially because the drug prevents gastric ulcers that can occur with long-term NSAID use. D. --Clients who have rheumatoid arthritis can take misoprostol, a prostaglandin E1 analog, especially because the drug prevents gastric ulcers that can occur with long-term NSAID use.

A nurse is caring for a client who has a new prescription for alosetron to treat irritable bowel syndrome. The nurse should instruct the client to report which of the following adverse effects of the drug? A. Headache B. Drowsiness C. Abdominal pain D. Sore throat

C. Abdominal pain Alosetron, a serotonin 5-HT3 receptor antagonist, can cause ischemic colitis. The nurse should tell the client to report abdominal pain, bloody diarrhea, or rectal bleeding, and to stop taking the drug if these manifestations occur. A. --Headache is not an adverse effect of alosetron, a serotonin 5-HT3 receptor antagonist. Ondansetron, a serotonin antagonist, is a GI-system drug that can cause headaches. B. --Drowsiness is not an adverse effect of alosetron, a serotonin 5-HT3 receptor antagonist. Alosetron is more likely to cause anxiety than drowsiness. D. --Alosetron, a serotonin 5-HT3 receptor antagonist, is unlikely to cause a sore throat or infections. Sulfasalazine, a 5-aminosalicylate, is a GI-system drug that can cause agranulocytosis and has reportable adverse effects including sore throat and fatigue.

A nurse is providing teaching to a client who has a new prescription for loperamide. Which of the following instructions should the nurse include? A. Dissolve the powder thoroughly in 8 oz (237 mL) of water B. Take with diphenhydramine to prevent extrapyramidal effects C. Avoid activities that require alertness D. Take 30 minutes before activities that trigger nausea

C. Avoid activities that require alertness Loperamide, an opioid agonist, can cause sedation and dizziness. The nurse should instruct the client to avoid taking it before activities that require alertness. A. --Loperamide, an opioid agonist, is available in tablets, capsules, or liquid form. Psyllium is a GI-system drug that comes in a powder to mix in 8 oz of water. B. --Loperamide, an opioid agonist, is unlikely to cause extrapyramidal effects. Metoclopramide is a GI-system drug that can cause extrapyramidal effects and can require taking diphenhydramine to help reverse these effects. D. --Loperamide, an opioid agonist, treats diarrhea, not nausea. Dimenhydrinate is a GI-system drug that requires taking it 30 min before activities that trigger nausea.

Which of the following drugs has protocols that require clients to meet specific risk-management criteria and sign a treatment agreement before the nurse can administer the drug? A. Lubiprostone B. Azathioprine C. Sulfasalazine D. Alosetron

D. Alosetron Clients who take alosetron, a serotonin 5-HT3 receptor antagonist, can develop severe constipation that can lead to impaction, bowel obstruction, perforation, and potentially fatal ischemic colitis. Because of these risks, nurses must inform clients of the benefits and risks of the drug therapy, and clients must sign a treatment agreement. A. --Although lubiprostone, a serotonin 5-HT4 receptor agonist, can cause potentially serious adverse effects, including nausea, vomiting, diarrhea, and headache, clients do not have to sign anything other than the standard consent forms prior to taking the drug. B. --Although azathioprine, an immunosuppressant, can cause potentially serious adverse effects, such as bone marrow suppression, clients do not have to sign anything other than the standard consent forms prior to taking the drug. C. --Although sulfasalazine, a 5-aminosalicylate, can cause potentially serious adverse effects, including hematologic disorders, clients do not have to sign anything other than the standard consent forms prior to taking the drug.

A nurse is caring for a client who has a new prescription for ranitidine to treat GERD. The nurse should instruct the client to wait at least 1 hour between taking ranitidine and which of the following over-the-counter drugs? A. Ginkgo biloba B. Antidiarrheals C. St. John's wort D. Antacids

D. Antacids Antacids can decrease the absorption of famotidine, a histamine2-receptor antagonist. The nurse should instruct the client to wait at least 1 hr between taking famotidine and taking an antacid. A. --Ginkgo biloba is a natural or herbal medication that is classified as an antiplatlet or central nervous system stimulant. There is no interaction with famotidine, a histamine2-receptor antagonist. B. --Antidiarrheal preparations do not specifically interact with famotidine, a histamine2-receptor antagonist. However, bismuth subsalicylate, which is used to treat diarrhea, can decrease the absorption of tetracycline and quinolones. C. --St. John's wort is a natural or herbal medication that is classified as an antidepressant. It does not specifically interact with famotidine, a histamine2-receptor antagonist.

A nurse is teaching a client who recently had a myocardial infarction and has a new prescription for docusate sodium. The nurse should inform the client that docusate sodium has which of the following therapeutic effects? A. Reduces inflammation B. Reduces gastric acid C. Prevents diarrhea D. Prevents straining

D. Prevents straining --Docusate sodium, a stool softener, prevents straining during defecation and prevents the elevation in blood pressure that can result from straining. It also helps relieve constipation and reduces the painful elimination of hard stools. A --Docusate sodium does not have anti-inflammatory effects. Sulfasalazine, a 5-aminosalicylate, is a GI-system drug that reduces the inflammation of inflammatory bowel disease. B. --Docusate sodium does not reduce gastric acid secretion. Omeprazole, a proton pump inhibitor, is a GI-system drug that reduces gastric acid secretion. C. --Docusate sodium does not prevent diarrhea. Loperamide, an opioid agonist, is a GI-system drug that prevents or treats diarrhea.

A nurse is caring for a client who is taking phenytoin for a seizure disorder and has a new prescription for sucralfate to treat a duodenal ulcer. The nurse should instruct the client to take the drugs at least 2 hours apart for which of the following reasons? A. Phenytoin increases the metabolism of sucralfate. B. Phenytoin reduces the effectiveness of sucralfate. C. Sucralfate increases the risk for phenytoin toxicity. D. Sucralfate interferes with the absorption of phenytoin.

D. Sucralfate interferes with the absorption of phenytoin. Sucralfate decreases the absorption of phenytoin. The nurse should instruct the client to allow at least 2 hr between taking the two drugs and should monitor the client's phenytoin levels. A. --Phenytoin increases the metabolism of oral contraceptives and corticosteroids. It is unlikely to increase the metabolism of sucralfate. B. --Phenytoin increases the metabolism of oral anticoagulants, reducing their effectiveness. It is unlikely to reduce the effectiveness of sucralfate. C. --Omeprazole, another GI-system drug, can increase phenytoin levels and increase the risk for phenytoin toxicity. Sucralfate is unlikely to increase the risk for phenytoin toxicity.