Question 58

Cephalexin warrants caution with respect to cross-sensitivity in patients with a penicillin allergy.

Cephalexin, a cephalosporin antibiotic, has a structural similarity to penicillin, which can lead to cross-sensitivity in individuals who are allergic to penicillin.

A) Doxycycline

Doxycycline is a tetracycline antibiotic and does not share a structural similarity with penicillin. Therefore, it is generally considered safe for use in patients with a known penicillin allergy, and caution regarding cross-sensitivity is not warranted.

B) Cephalexin

Cephalexin is a first-generation cephalosporin that can cause allergic reactions in some patients who are allergic to penicillin. This is due to the similar beta-lactam structure, which may trigger an immune response in sensitive individuals, making it necessary to exercise caution.

C) Clindamycin

Clindamycin is a lincosamide antibiotic that does not have a beta-lactam structure and therefore does not pose a risk of cross-sensitivity for patients with penicillin allergies. It is considered a safe alternative for these patients.

D) Metronidazole

Metronidazole is an antibiotic that belongs to a different class (nitroimidazole) and has no structural similarities to penicillin. As such, it does not warrant caution regarding cross-sensitivity in patients with a penicillin allergy.

Conclusion

Cephalexin is the correct answer as it poses a risk of cross-sensitivity in patients with a penicillin allergy due to its structural similarities. In contrast, doxycycline, clindamycin, and metronidazole do not share these structural features and are considered safe alternatives for individuals with penicillin allergies. Hence, cephalexin is the only medication from the options that requires caution.