What are the most commonly used cancer drugs?, Pg10

Context:

• A global investigation published in The Hindu reveals that widely-used chemotherapy drugs exported to over 100 countries have failed quality tests. 

Key Highlights:

• The drugs investigated include cisplatin, oxaliplatin, cyclophosphamide, doxorubicin, methotrexate, and leucovorin.
• These are critical components of standard chemotherapy regimens across multiple cancer types.
• The drugs function by damaging DNA, thereby preventing cancer cells from dividing and spreading.
• All six drugs carry severe side effects, impacting organs such as the heart, kidneys, and bone marrow.
• Leucovorin is used not as a chemotherapy drug but as a rescue agent to reduce the toxicity of methotrexate.

Detailed Insights:

• Cisplatin binds to DNA and stops cancer cell division; used for testicular, ovarian, bladder, and lung cancers.
• Cisplatin causes side effects such as kidney damage, hearing loss, nausea, and bone marrow suppression.
• Oxaliplatin works like cisplatin and is used for colorectal cancer, especially post-surgery.
• Oxaliplatin causes neurotoxicity, nausea, and reduced immune function.
• Cyclophosphamide disrupts DNA and is used in breast cancer, leukemia, sarcoma, and lymphoma.
• Cyclophosphamide leads to white blood cell depletion and bladder inflammation.
• Doxorubicin interferes with DNA synthesis and is used in breast cancer, leukemia, lymphoma, and sarcoma.
• Doxorubicin has serious side effects like irreversible heart damage, increased infection risk, and hair loss.
• Methotrexate inhibits enzymes needed for DNA synthesis and treats leukemia, lymphoma, and tumors.
• Methotrexate can cause liver damage, immune suppression, and severe mouth ulcers.
• Leucovorin is a folinic acid derivative that protects healthy cells during methotrexate therapy.
• Leucovorin is not cytotoxic and is essential to mitigate methotrexate's adverse effects.

Critical Issues Raised:

• Export of poor-quality cancer drugs undermines treatment outcomes and raises mortality risks.
• Inadequate international regulation allows circulation of substandard medicines.
• Patients are exposed to toxicity without therapeutic benefit if drug potency is compromised.
• Ethical concerns arise over pharma companies prioritising profit over patient safety.

Way Forward:

• Enforce rigorous batch-wise drug quality testing for both domestic and exported drugs
• Establish international pharmacovigilance protocols under WHO or regional blocs
• Mandate public reporting of clinical efficacy and adverse events
• Adopt real-time monitoring systems for tracing drug origin and test compliance
• Strengthen licensing and penalties for drug manufacturers violating standards. 

Scientific Concepts Involved:

• Chemotherapy: Treatment using drugs to kill or stop the growth of cancer cells by damaging their DNA or interfering with cell division.
• DNA Alkylation: The process of adding alkyl groups to DNA, causing damage that inhibits cancer cell replication.
• Chemoprotectants: Substances like leucovorin used to protect normal cells from chemotherapy side effects.
• Pharmacovigilance: The practice of monitoring the safety and efficacy of drugs after they reach the market.