Which of the following is a radioprotector?
**Core Concept**
Radioprotectors are substances that can reduce the damage caused by ionizing radiation to living tissues. They work by scavenging free radicals, stabilizing DNA, or inhibiting enzymes involved in radiation-induced damage.
**Why the Correct Answer is Right**
Amifostine is a well-known radioprotector that is used to reduce the incidence of xerostomia (dry mouth) and mucositis in patients undergoing radiation therapy for head and neck cancer. It works by scavenging free radicals and inhibiting the enzyme topoisomerase II, which is involved in DNA damage. Amifostine also has a protective effect on the kidneys and salivary glands, making it a valuable adjunct in radiation therapy.
**Why Each Wrong Option is Incorrect**
**Option A:** Hydroxyurea is a chemotherapy agent, not a radioprotector. It works by inhibiting ribonucleotide reductase, an enzyme involved in DNA synthesis.
**Option B:** Cisplatin is a platinum-based chemotherapy agent that can cause nephrotoxicity, but it is not a radioprotector. It works by forming platinum-DNA adducts, which inhibit DNA replication and transcription.
**Option C:** Paclitaxel is a taxane chemotherapy agent that stabilizes microtubules, preventing cell division. It is not a radioprotector and can cause neurotoxicity and myelosuppression.
**Clinical Pearl / High-Yield Fact**
Radioprotectors like amifostine can reduce the incidence of radiation-induced side effects, but they do not affect the efficacy of radiation therapy. Always consider the potential benefits and risks of radioprotectors in the context of individual patient care.
**Correct Answer:** B. Amifostine.