Patients with allergies to penicillins often have cross-allergies to cephalosporins. Cephalosporins such as ceftriaxone should be avoided by patients with these allergies. Patients with cephalosporin allergies should also avoid pencillins. Streptomycin, ciprofloxacin, clindamycin, and sulfasalazine may all treat UTIs but are not penicillins.

The nurse should identify alendronate as a medication that slows bone loss, and is commonly prescribed to patients with osteoporosis to maintain bone density. The nurse should assess ages and risk factors associated with both osteoporosis and alendronate use. Alendronate is contraindicated in patients who are allergic to it, have esophageal issues such as narrowing or blockages, are unable to sit or stand upright for 30 minutes (after taking), or have kidney dysfunction or low blood calcium levels. Therefore, the nurse should question the order of alendronate for the 70-year-old female with chronic kidney disease. The nurse should also recognize that older patients are more likely to experience problems such as contraindications with medications due to polypharmacy, so the age of the 70-year-old female should concern the nurse. Alendronate is not contraindicated in patients who are on low-calorie diets, and it is not contraindicated with estrogen or captopril.

Blood donors must be healthy and feeling well to donate blood; they must also be free of blood-borne pathogens such as HIV/AIDS and hepatitis B, C, and D. Diverticulosis, Crohn’s disease, a previous cholecystectomy, and a dose of ibuprofen the previous day do not preclude this person from donating blood.

Patients with acute gastritis experience inflammation in the gastric mucosa. They must discontinue use of drugs that may cause gastritis or inflammation, such as NSAIDs like ibuprofen or alcohol consumptions. Calcium gluconate, furosemide, acetaminophen, and propranolol are not associated with acute gastritis and can be taken safely by this patient.

Tyramine is an amino-acid that is present in many foods, including fermented, aged, or smoked foods, aged cheese, fish, pork, cold cuts, chocolate, alcohol, yeasty breads, peanuts, and beans. High tyramine intake in patients on MAOI's can cause hypertensive crisis due to monoamine oxidase's role in tyramine breakdown.

Drinking alcohol while taking metronidazole can result in nausea, vomiting, flushing, and tachycardia. This is due to metronidazole's inhibition of acetaldehyde dehydrogenase, the enzyme responsible for acetaldehyde catabolism. Reduced function of acetaldehyde dehydrogenase results in toxic levels of acetaldehyde in the blood.

Tyramine is normally broken down by monoamine oxidase. Monoamine oxidase inhibitors prevent the breakdown and removal, leading abnormally high tyrosine levels in the body. This can in turn displace the storage and increase release of multiple other catecholamines, including dopamine, epinephrine, and norepinephrine. This increase in free catecholamines can cause a hypertensive crisis.

The correct answer is "Do not consume grapefruit juice while taking warfarin." 

This advice is correct because warfarin is metabolized and inactivated by the cytochrome P-450 (CYP450) enzyme complex, and grapefruit juice is an inhibitor of CYP450. Therefore, when grapefruit juice is consumed, the efficacy of inactivation of drugs, like warfarin, is impaired, which increases the effective level of warfarin circulating in the patient's blood. Consequently, even if the patient is taking the prescribed dose of warfarin, the effect of the drug may be greater than intended if taken with grapefruit juice, which can predispose to dangerous, potentially fatal bleeding effects. Thus, avoiding grapefruit juice while taking warfarin is the most appropriate advice for this patient.

The patient's risk of bleeding events is elevated while taking warfarin, even without consuming grapefruit juice, though the benefit of preventing future blood clots and pulmonary emboli outweighs the risk of bleeding. Due to the risk of bleeding events while taking warfarin, it would be inappropriate to advise the patient to continue participating in contact sports.

Warfarin is not known to cause an increased risk of seizures.

It would be inappropriate to advise a patient to discontinue taking aspirin while on warfarin unless explicitly instructed for a medical reason by his physician. While aspirin is an anti-platelet agent, which can predispose to bleeding, and warfarin is an anti-coagulant, which also independently can predispose to bleeding, each medication has a clinical indication in the patient, and therefore it is inappropriate to simply discontinue one medication.

The correct answer is "Ciprofloxacin."

This choice is correct because the combined oral contraceptive pill (OCP) is metabolized and inactivated by the cytochrome P-450 (CYP450) enzyme complex, and ciprofloxacin, a fluoroquinolone antibiotic, is an inhibitor of CYP450. Therefore, when ciprofloxacin is taken, the efficacy of inactivation of drugs, like OCP's, is impaired, which increases the effective level of OCP's circulating in the patient's blood. Consequently, even if the patient is taking the prescribed dose of OCP's, the effect of the drug may be greater than intended if taken with ciprofloxacin or other drugs that inhibit CYP450, which can make the potential adverse effects of OCP's more likely to occur, or occur with greater severity than if that patient had not taken ciprofloxacin with it. 

Neither lisinopril (an ACE inhibitor), fluoxetine (an SSRI), Docusate (a stool softener), nor aspirin (an anti-inflammatory, anti-platelet agent) appreciably induce or inhibit CYP450 and therefore none of them has an appreciable effect on OCP metabolism.

The correct answer is "St. John's wort." 

This question tests your knowledge of factors that influence the metabolism of warfarin. In this case, you are told that the patient is taking an appropriate dose of warfarin, but still is not achieving the desired therapeutic effect, which raises the possibility of drug interactions and/or use of other medications that may impact the metabolism of warfarin.

Warfarin is metabolized by the CYP450 enzyme complex, which is known to be induced and inhibited by a variety of other common medications, supplements, and foods. Since this patient's International Normalized Ratio (INR) is sub-therapeutic, meaning that warfarin is not achieving a great enough effect, this should raise the possibility of increased metabolism of warfarin by CYP450, which means that warfarin will be inactivated more quickly than usual. The only agent listed that is known to induce or activate CYP450, which would speed the inactivation of warfarin, is St. John's wort, an herb commonly used for antidepressant activity and anti-inflammatory activity.

Gemfibrozil, quinidine, cimetidine, and azithromycin all are inhibitors of CYP450, not inducers, and therefore would slow the metabolism of warfarin, increasing the effective circulating dose of warfarin, which would raise the INR. Therefore, these are not correct answer choices for this case.