Relative to cisplatin, the greatest benefit of carboplatin is its reduced side effects, particularly the elimination of nephrotoxic effects. Nausea and vomiting are less severe and more easily controlled.[9]
The main drawback of carboplatin is its myelosuppressive effect. This causes the blood cell and platelet output of bone marrow in the body to decrease quite dramatically, sometimes as low as 10% of its usual production levels. The nadir of this myelosuppression usually occurs 21–28 days after the first treatment, after which the blood cell and platelet levels in the blood begin to stabilize, often coming close to its pre-carboplatin levels. This decrease in white blood cells (neutropenia) can cause complications, and is sometimes treated with drugs like filgrastim. The most notable complication of neutropenia is increased probability of infection by opportunistic organisms, which necessitates hospital readmission and treatment with antibiotics.
Mechanism of action
Carboplatin differs from cisplatin in that it has a bidentate dicarboxylate (the ligand is cyclobutane dicarboxylate, CBDCA) in place of the two chlorideligands. Both drugs are alkylating agents. CBDCA and chloride are the leaving groups in these respective drugs Carboplatin exhibits slower aquation (replacement of CBDCA by water) and thus slower DNA binding kinetics, although it forms the same reaction products in vitro at equivalent doses with cisplatin. Unlike cisplatin, carboplatin may be susceptible to alternative mechanisms. Some results show that cisplatin and carboplatin cause different morphological changes in MCF-7 cell lines while exerting their cytotoxic behaviour.[10] The diminished reactivity limits protein-carboplatin complexes, which are excreted. The lower excretion rate of carboplatin means that more is retained in the body, and hence its effects are longer lasting (a retention half-life of 30 hours for carboplatin, compared to 1.5-3.6 hours in the case of cisplatin).
Like cisplatin, carboplatin binds to and cross-links DNA, interfering with the replication and suppressing growth of the cancer cell.[11][12]
Dose
Calvert's formula is used to calculate the dose of carboplatin. It considers the creatinine clearance and the desired area under curve.[13] After 24 hours, close to 70% of carboplatin is excreted in the urine unchanged. This means that the dose of carboplatin must be adjusted for any impairment in kidney function.[14]
Calvert formula:
The typical area under the curve (AUC) for carboplatin ranges from 3-7 (mg/ml)*min.[14]
Synthesis
Cisplatin reacts with silver nitrate and then cyclobutane-1,1-dicarboxylic acid to form carboplatin.[15]
History
Carboplatin, a cisplatin analogue, was developed by Bristol Myers Squibb and the Institute of Cancer Research in order to reduce the toxicity of cisplatin.[6][16] It gained U.S. Food and Drug Administration (FDA) approval for carboplatin, under the brand name Paraplatin, in March 1989. Starting in October 2004, generic versions of the drug became available.
Research
Carboplatin has also been used for adjuvant therapy of stage 1 seminomatous testicular cancer. Research has indicated that it is not less effective than adjuvant radiotherapy for this treatment, while having fewer side effects.[17] This has led to carboplatin based adjuvant therapy being generally preferred over adjuvant radiotherapy in clinical practice.[18]
^ abcdefghi"Carboplatin". The American Society of Health-System Pharmacists. Archived from the original on 21 December 2016. Retrieved 8 December 2016.
^Oun R, Moussa YE, Wheate NJ (May 2018). "The side effects of platinum-based chemotherapy drugs: a review for chemists". Dalton Transactions. 47 (19): 6645–6653. doi:10.1039/c8dt00838h. PMID29632935.
^World Health Organization (2023). The selection and use of essential medicines 2023: web annex A: World Health Organization model list of essential medicines: 23rd list (2023). Geneva: World Health Organization. hdl:10665/371090. WHO/MHP/HPS/EML/2023.02.
^Gulbis AM, Wallis WD (2023). "10 - Preparative Regimens Used in Hematopoietic Cell Transplantation and Chimeric Antigen Receptor T-Cell Therapies". Manual of Hematopoietic Cell Transplantation and Cellular Therapies. Elsevier. pp. 125–143. doi:10.1016/B978-0-323-79833-4.00010-3. ISBN9780323798334.
^Natarajan G, Malathi R, Holler E (November 1999). "Increased DNA-binding activity of cis-1,1-cyclobutanedicarboxylatodiammineplatinum(II) (carboplatin) in the presence of nucleophiles and human breast cancer MCF-7 cell cytoplasmic extracts: activation theory revisited". Biochemical Pharmacology. 58 (10): 1625–1629. doi:10.1016/S0006-2952(99)00250-6. PMID10535754.
^O'Cearbhaill R, Sabbatini PS (September 1, 2012). "New Guidelines for Carboplatin Dosing". Memorial Sloan Kettering Cancer Center. Archived from the original on 2014-10-31. Retrieved 2014-03-27.
^ abCalvert AH, Newell DR, Gumbrell LA, O'Reilly S, Burnell M, Boxall FE, et al. (November 1989). "Carboplatin dosage: prospective evaluation of a simple formula based on renal function". Journal of Clinical Oncology. 7 (11): 1748–1756. doi:10.1200/JCO.1989.7.11.1748. PMID2681557.
Canetta R, Rozencweig M, Carter SK (September 1985). "Carboplatin: the clinical spectrum to date". Cancer Treatment Reviews. 12 Suppl A (Suppl A): 125–136. doi:10.1016/0305-7372(85)90027-1. PMID3002623.
Yang XL, Wang AH (September 1999). "Structural studies of atom-specific anticancer drugs acting on DNA". Pharmacology & Therapeutics. 83 (3): 181–215. doi:10.1016/S0163-7258(99)00020-0. PMID10576292.