Ribociclib Succinate is being supplied by MedicaPharma in GMP grade.
Ribociclib Succinate was approved by the U.S. Food and Drug Administration (FDA) in March 2017, and the European Medicines Agency (EMA) in August 2017, for use in combination with an aromatase inhibitor (such as letrozole) to treat HR-positive, HER2-negative advanced or metastatic breast cancers.
In the clinical trial relevant for the drug’s approval, ribociclib significantly improved progression-free survival (PFS), that is, the time span the cancer did not get worse.
The most common side effects in studies were decreased blood cell counts, mainly neutropenia (in 75% of patients, as compared to 5% under placebo), but also anemia (18% vs. 5%). Gastrointestinal disorders were also common, for example nausea (52% vs. 29%) and diarrhea (35% vs. 22%), as was alopecia (33% vs. 16%). The drug also increases the QT interval and liver enzymes (alanine transaminase, aspartate transaminase).
As ribociclib succinate is mainly metabolized by the liver enzyme CYP3A4, inhibitors of this enzyme increase its concentrations in the body and could potentiate side effects and toxicity. Examples of such inhibitors include ketoconazole and similar antifungal drugs, ritonavir, clarithromycin, as well as grapefruit. Conversely, drugs that induce CYP3A4, such as rifampicin and St John’s Wort, can decrease ribociclib concentrations. Ribociclib itself is a moderate to strong CYP3A4 inhibitor and therefore can increase concentrations of other drugs that share this metabolism, as has been shown with midazolam. It also inhibits a number of transporter proteins and could thus theoretically interfere with the transport of other drugs in the body. It could also amplify QT prolongation of other drugs such as antiarrhythmics, clarithromycin, and haloperidol.
The percentage of ribociclib succinate absorbed in the gut has not been determined. Highest blood plasma levels are reached after one to four hours; and after repeated dosage, steady state concentrations are reached after about eight days. Food intake has no effect on absorption rates. When in the bloodstream, about 70% of ribociclib are bound to plasma proteins.
The substance is mainly metabolized by CYP3A4 and subsequently by various phase II enzymes, resulting in a large number of metabolites. Those with highest blood plasma concentrations in humans are called CCI284 (an unspecified N-hydroxylation product), LEQ803 (the N-demethylation product) and M1 (a glucuronide). All metabolites have negligible clinical activity. Ribociclib succinate has a slight tendency to accumulate in the body. It is eliminated with an average biological half-life of 32 hours, mostly (69%) via the feces, but also (23%) via the urine. The unchanged drug accounts for 17% of the substance in the feces and 12% of the substance in the urine, the rest being metabolites (source Wikipedia).