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?

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.

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.