Mechlorethamine

**Mechlorethamine** (also known as nitrogen mustard) is a highly potent, cell-cycle nonspecific antineoplastic agent. It is historically significant as the first nitrogen mustard alkylating agent used in chemotherapy. In veterinary medicine, it is primarily utilized as an adjunctive treatment for lymphoreticular neoplasms, most notably as the "M" in the **MOPP rescue protocol** (Mechlorethamine, Oncovin [vincristine], Procarbazine, Prednisone) for relapsing canine and feline lymphoma. > **Clinical Pearl:** Mechlorethamine is a severe vesicant. Extreme care must be taken during intravenous administration to avoid extravasation, which can lead to devastating tissue necrosis and sloughing. Due to significant price increases and availability issues, some veterinary oncologists substitute dactinomycin or lomustine (CCNU) in rescue protocols. It can also be administered intracavitarily to treat malignant pleural and peritoneal effusions, where it acts as a sclerosing agent to cause adherence of serosal surfaces.

กลไกการออกฤทธิ์: Mechlorethamine is a **bifunctional alkylating agent**. * **Mechanism:** It undergoes intramolecular cyclization to form a highly reactive aziridinium ion. This ion reacts with nucleophilic sites on DNA (primarily the N7 position of guanine). * **Pathway:** Alkylation → **Cross-linking of DNA strands** (interstrand and intrastrand) → Inhibition of DNA replication and RNA transcription → Cell death (apoptosis). * It is **cell cycle-phase nonspecific**, meaning it can kill cells in any phase of the cell cycle, though it is most toxic to rapidly dividing cells. * When given intracavitarily, it induces a strong inflammatory response on serous membranes, leading to sclerosis and obliteration of the cavity space.

ข้อมูลอ้างอิงยาของ VetSheet มีไว้สำหรับสัตวแพทย์ผู้มีใบอนุญาตเพื่อช่วยในการตัดสินใจทางคลินิก ไม่ใช่สิ่งทดแทนการวินิจฉัยของผู้เชี่ยวชาญหรือฉลากล่าสุดของผู้ผลิต