How Do Chemotherapy Rescue Agents Work?

Chemotherapy rescue agents are a class of drugs used to treat and prevent serious blood cell disorders such as thrombocytopenia (low blood platelet count), neutropenia (low neutrophil count), and anemia (low red blood cell count) caused by methotrexate (cancer chemotherapy and anti-rheumatic medication), accidental overdose of methotrexate, methanol poisoning, and trimethoprim (an antibiotic) toxicity.

The only drug that belongs to this class is “leucovorin,” a synthetic form of folic acid and a naturally occurring B vitamin that helps the body to produce new healthy cells. It is also crucial for the synthesis and repair of DNA and other genetic materials.

Folic acid must be reduced by the enzyme dihydrofolate reductase (DHFR) into the cofactors dihydrofolate (DHF) and tetrahydrofolate (THF), an essential pathway for the synthesis of nucleic acids and amino acids. However, methotrexate acts as a DHFR inhibitor to prevent DNA synthesis in rapidly dividing cells; it also prevents the formation of DHF and THF, resulting in a deficiency of coenzymes and accumulation of toxic substances that are responsible for numerous adverse side effects associated with methotrexate therapy.

Chemotherapy rescue agents are administered via injectable and oral routes, typically every six hours or once daily.

Chemotherapy rescue agents belong to a class of medications called “folic acid analogs” that work by protecting healthy cells from the harmful effects of methotrexate (a folic acid antagonists).

Chemotherapy rescue agents are used to treat conditions such as:

• Methotrexate overdose
• Megaloblastic anemia because of folate deficiency
• Advanced colorectal carcinoma
• Methanol poisoning
• Trimethoprim toxicity

Some of the common side effects include:

• Nausea
• Vomiting
• Diarrhea
• Stomatitis (inflammation of the mucous membrane of the mouth)

Other rare side effects include:

• Dizziness 
• Hives/rash/itching
• Difficulty breathing
• Swelling the face/tongue/throat
• Thrombocytosis (high blood platelet count)
• Wheezing
• Anaphylactic reactions (a severe, potentially life-threatening allergic reaction)

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Generic name of chemotherapy rescue agent includes:

• Leucovorin