Gimeracil

Warning

H302 (100%): Harmful if swallowed [Warning Acute toxicity, oral]

P261, P264, P264+P265, P270, P271, P280, P301+P317, P302+P352, P304+P340, P305+P351+P338, P319, P321, P330, P332+P317, P337+P317, P362+P364, P403+P233, P405, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 2 reports by companies from 2 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Gimeracil's main role within Teysuno is to prevent the breakdown of [DB00544] (5-FU), which helps to maintin high enough concentrations for sustained effect against cancer cells. It functions by reversibly blocking the enzyme dihydropyrimidine dehydrogenase (DPD), which is involved in the degradation of 5-FU.

Mean 5-FU maximum plasma concentration (Cmax) and area under the concentration-time curve (AUC) values were approximately 3-fold higher after Teysuno administration than after administration of tegafur alone, despite a 16-fold lower Teysuno dose (50 mg of tegafur) compared to tegafur alone (800 mg), and are attributed to inhibition of DPD by gimeracil. Maximum plasma uracil concentration was observed at 4 hours, with a return to baseline levels within approximately 48 hours after dosing, indicating the reversibility of the DPD inhibition by gimeracil. After administration of a single dose of 50 mg Teysuno (expressed as tegafur content), median Tmax for Teysuno components tegafur, gimeracil, and oteracil was 0.5, 1.0, and 2.0 hours, respectively.

Following a single dose of Teysuno, approximately 3.8% to 4.2% of administered tegafur, 65% to 72% of administered gimeracil, and 3.5% to 3.9% of administered oteracil were excreted unchanged in the urine.

Although no intravenous data are available for Teysuno in humans, the volume of distribution could be roughly estimated from the apparent volume of distribution and urinary excretion data as 16 l/m2, 17 l/m2, and 23 l/m2 for tegafur, gimeracil and oteracil, respectively.