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?

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.

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.