What Factors Affect a Sufficient Carboplatin Dose?

Canaan Downs

A member of a class of drugs known as alkylating agents, carboplatin is a medication predominantly used as a cancer treatment, particularly for cancer of the ovaries. Alkylating agents work by interfering with cancer cell growth, eventually causing these cells to die off at a greater rate than that of healthy cells within the patient's body. Some medications may interact with carboplatin, making it necessary to adjust their dosages if they cannot be entirely removed from the patient's treatment regimen. Other factors that may affect the appropriate carboplatin dose include the patient's level of kidney function, response to previous treatments, and the form of cancer to be treated.

Blood samples may be required to determine platelet counts to establish the correct carboplatin dosage.
Blood samples may be required to determine platelet counts to establish the correct carboplatin dosage.

As a monotherapy for ovarian cancer, the standard adult carboplatin dose is 360 mg/m2 carboplatin dose administered intravenously on day one every four weeks. Repeat doses are not generally given until the patient's platelet count is over 100,000 and his or her neutrophil count is over 2,000. When carboplatin is administered alongside cyclophosphamide, the standard dose is reduced to 300 mg/m2 for six cycles of four weeks. Some physicians instead apply an algorithm known as the Calvert formula to determine carboplatin dosages.

When determining the appropriate carboplatin dose to administer for patients who have been treated with carboplatin in the past, it is essential that their platelet count and performance status be measured prior to treatment. In patients with platelet counts of greater than 100,000 and neutrophil counts of greater than 2,000, the carboplatin dose may be increased by 125 percent, while those with platelet counts of less than 50,000 or neutrophil counts of less than 500 should receive 75 percent of the standard dose. Patients with platelet counts of between 50,000 and 100,000 and neutrophil counts of 500 to 2,000 require no adjustment to their carboplatin dose. Those demonstrating severe myelosuppression have in some cases received doses as low as 50 to 60 percent of the typical dose. These adjustments to carboplatin does the same when the drug is being used as a montherapeutic agent or when it is used in combination with cyclophosphamide.

Additional adjustments to carboplatin dosage may be required for patients suffering from diminished levels of kidney function, as reductions in kidney function may produce an idiosyncratic increase in serum levels of the drug. These patients are at a significantly higher risk of developing severe leukopenia, thrombocytopenia and neutropenia than other patients, even with the following modifications to their carboplatin dose. Patients with a creatinine clearence level of 41 to 59 mL/min should receive 250 mg/m2 on day one of treatment. Those with creatinine clearance of 16 to 40 mL/min should receive 200 mg/m2 on day one. These dosage recommendations must be adjusted according to the patient's tolerance and level of bone marrow suppression in subsequent treatments.

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