Antibiotics and Antimicrobial Agents > Pharmacology
Exam Review
Interactions and contraindications
Total Questions : 5
Showing 5 questions, Sign in for moreA nurse is preparing to administer penicillin to a client who has a bacterial infection. The client also takes probenecid for gout.
What effect will probenecid have on the penicillin?
Explanation
It will increase the serum levels and half-life of penicillin.Probenecid inhibits the renal excretion of penicillin, which prolongs its action and increases its concentration in the blood. This can be beneficial for treating severe infections, but it also increases the risk of adverse effects and toxicity.
Choice B is wrong because probenecid does not affect the absorption or bioavailability of penicillin.
These factors depend on the route of administration and the formulation of the drug.
Choice C is wrong because probenecid does not enhance the bactericidal activity of penicillin.
Penicillin kills bacteria by interfering with their cell wall synthesis, which is independent of probenecid.
Choice D is wrong because probenecid does not reduce the risk of allergic reaction to penicillin.In fact, probenecid may increase the risk of hypersensitivity reactions by prolonging the exposure to penicillin.
Normal ranges for serum levels and half-life of penicillin vary depending on the type and dose of penicillin, but generally they are between 2 to 40 mcg/mL and 0.5 to 1.5 hours, respectively.
A nurse is caring for a client who is receiving vancomycin for a severe infection caused by methicillin-resistant Staphylococcus aureus (MRSA). The client also takes furosemide for heart failure.
Which of the following adverse effects should the nurse monitor for in this client? (Select all that apply.).
Explanation
Hearing loss and nephrotoxicity are possible adverse effects of vancomycin, especially when used with other drugs that can affect the kidneys or ears, such as furosemide. The nurse should monitor the client’s renal function tests, serum vancomycin levels, and hearing acuity while receiving this combination of drugs.
Choice C, red man syndrome, is a hypersensitivity reaction to vancomycin that causes flushing, itching, and rash on the face, neck, and upper body.It is not related to furosemide use and can be prevented by slowing the infusion rate of vancomycin.
Choice D, hypokalemia, is a low level of potassium in the blood that can be caused by furosemide, a loop diuretic that increases the excretion of potassium.However, vancomycin does not affect potassium levels and does not increase the risk of hypokalemia.
Choice E, thrombocytopenia, is a low level of platelets in the blood that can cause bleeding problems.
It is a rare side effect of vancomycin that occurs in less than 1% of patients.It is not related to furosemide use and does not occur more frequently with this combination of drugs.
A nurse is teaching a client who has a urinary tract infection (UTI) about trimethoprim/sulfamethoxazole. The client asks why he needs to take two antibiotics together.
What should the nurse say?
Explanation
The combination of trimethoprim and sulfamethoxazole has a synergistic effect that inhibits bacterial growth more effectively than either drug alone. This means that the two drugs work together to produce a greater effect than the sum of their individual effects.
Choice B is wrong because the combination of trimethoprim and sulfamethoxazole does not have an additive effect that reduces the dosage and frequency of administration of each drug.
The dosage and frequency of administration are determined by the severity of the infection, the renal function of the client, and the susceptibility of the bacteria.
Choice C is wrong because the combination of trimethoprim and sulfamethoxazole does not have an antagonistic effect that prevents the development of resistance to either drug.
Antagonistic effect means that one drug reduces or cancels out the effect of another drug.
The combination of trimethoprim and sulfamethoxazole may still cause resistance in some bacteria.
Choice D is wrong because the combination of trimethoprim and sulfamethoxazole does not have a selective effect that targets only the bacteria causing the UTI and spares the normal flora.
Selective effect means that a drug affects only certain types of cells or organisms.
The combination of trimethoprim and sulfamethoxazole is a broad-spectrum antibiotic that can affect both gram-positive and gram-negative bacteria, including some normal flora.
A nurse is administering tetracycline to a client who has acne vulgaris. The client tells the nurse that he usually takes calcium supplements with his meals.
How should the nurse respond?
Explanation
You should take calcium supplements at least 2 hours before or after tetracycline.This is because calcium can interfere with the absorption of tetracycline and reduce its effectiveness.
Choice A is wrong because taking calcium supplements with food does not prevent the interaction with tetracycline.
Choice B is wrong because avoiding calcium supplements altogether is not necessary and may deprive the client of an important nutrient.
Choice C is wrong because drinking plenty of water does not prevent the interaction with tetracycline either.
Normal ranges for calcium are 8.5 to 10.2 mg/dL for adults.Tetracycline is an antibiotic that is used to treat acne vulgaris and other infections.It should be taken on an empty stomach with a full glass of water.
A nurse is reviewing the medication history of a client who is prescribed azithromycin for a respiratory infection. The nurse notes that the client is also taking warfarin for atrial fibrillation.
What action should the nurse take?
Explanation
There is conflicting evidence about the interaction between azithromycin and warfarin.Some studies suggest that azithromycin does not affect warfarin metabolism or prothrombin time, while others report that azithromycin may enhance warfarin’s effects and increase the risk of bleeding or bruising.The FDA approved label revisions for azithromycin warn of a potential interaction with warfarin. Therefore, the nurse should inform the prescriber about this possible interaction and monitor the client’s prothrombin time or International Normalized Ratio (INR) periodically.
Choice B is wrong because it is not enough to instruct the client to monitor for signs of bleeding, such as bruising, hematuria, or melena.
The nurse should also inform the prescriber and check the client’s INR regularly.
Choice C is wrong because it is not advisable to advise the client to increase the intake of vitamin K-rich foods, such as green leafy vegetables, while taking azithromycin.
Vitamin K can reduce the effectiveness of warfarin and increase the risk of clotting.The client should maintain a consistent level of vitamin K intake throughout the treatment with warfarin.
Choice D is wrong because it is not relevant to the question.
Azithromycin does not affect hormonal contraception, such as pills, patches, or rings.The client does not need to use an alternative form of contraception, such as condoms, while taking azithromycin.
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