Supportive Care Drugs in Oncology
Supportive care drugs manage chemotherapy toxicities including nausea, myelosuppression, pain, and metabolic emergencies to maintain treatment tolerability.
Overview
Supportive care pharmacology enables cancer patients to tolerate aggressive treatment regimens by preventing and managing treatment-related toxicities. Effective antiemesis, myeloid growth factor support, and pain management are essential components of modern oncology practice.
Antiemetics
Chemotherapy-induced nausea and vomiting (CINV) is classified as highly emetogenic (HEC, >90% incidence without prophylaxis), moderately emetogenic (MEC, 30-90%), or low/minimal emetogenic.
- 5-HT3 antagonists (ondansetron, granisetron, palonosetron): Block serotonin receptors on vagal afferents and in the vomiting center. Palonosetron has higher receptor affinity and a 40-hour half-life.
- NK1 antagonists (aprepitant, fosaprepitant, netupitant): Block substance P/NK1 receptors in the CNS. Essential for HEC prophylaxis. Aprepitant is a CYP3A4 inhibitor — monitor for drug interactions.
- Dexamethasone: Mechanism of antiemetic effect unclear; enhances efficacy of all other antiemetics.
- Olanzapine: Added to 3-drug regimen for highly refractory CINV.
Myeloid Growth Factors
G-CSF (filgrastim, pegfilgrastim): Stimulates neutrophil production from bone marrow progenitors. Reduces duration and severity of chemotherapy-induced neutropenia. Pegfilgrastim (PEGylated) has a long half-life, administered once per cycle. Primary prophylaxis when febrile neutropenia risk >20%.
Erythropoiesis-stimulating agents (epoetin alfa, darbepoetin): Treat chemotherapy-related anemia (Hgb <10 g/dL); avoid if curable intent treatment (possible tumor-promoting effect).
Bone-Modifying Agents
Bisphosphonates (zoledronic acid, pamidronate) and denosumab (anti-RANK-L) reduce skeletal-related events (fractures, cord compression, hypercalcemia) in bone metastases. Osteonecrosis of the jaw (ONJ) is a class effect; dental evaluation required before initiating.
Tumor Lysis Syndrome Prevention
Allopurinol (xanthine oxidase inhibitor) or rasburicase (urate oxidase, degrades existing uric acid) prevent uric acid nephropathy in high-risk patients (Burkitt lymphoma, bulky ALL).
Key Takeaways
- HEC prophylaxis requires triple therapy: NK1 antagonist + 5-HT3 antagonist + dexamethasone
- Pegfilgrastim provides convenient once-per-cycle G-CSF support; start 24-72h after chemotherapy
- Denosumab and bisphosphonates reduce skeletal events in bone metastases
- Rasburicase (not allopurinol) is preferred for established hyperuricemia and high-risk tumor lysis