Gimeracil, molecular formula C5H4ClNO2, CAS 103766-25-2, It is an organic compound with biological activity. The raw material is a white to off white crystalline powder with a slightly glossy surface. Scanning electron microscopy (SEM) observation shows that the crystal presents an irregular sheet-like structure with a particle size distribution range of 20-80 μ m, which meets the basic requirements for flowability of pharmaceutical excipients. Often used as a component of anti-tumor drug formulations (such as Tegio capsules), it enhances the anti-tumor effect of fluorouracil by inhibiting the activity of dihydropyrimidine dehydrogenase (DPD).

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Chemical Formula |
C5H4ClNO2 |
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Exact Mass |
145 |
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Molecular Weight |
146 |
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m/z |
145 (100.0%), 147 (32.0%), 146 (5.4%), 148 (1.7%) |
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Elemental Analysis |
C, 41.26; H, 2.77; Cl, 24.36; N, 9.62; O, 21.99 |
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Gimeracil COA


Pharmacological mechanism of action and core functions
As a DPD inhibitor, gemcitabine shows significant advantages in the treatment of gastrointestinal tumors, pancreatic cancer and other solid tumors by optimizing the pharmacokinetics of fluorouracil. Its clinical application has expanded from standard chemotherapy regimens to multiple dimensions such as individualized treatment, conversion therapy, and combination immunotherapy.

As a dihydropyrimidine dehydrogenase (DPD) inhibitor, Gimeracil significantly prolongs the half-life of fluorouracil (5-FU) in plasma by specifically blocking DPD activity, thereby enhancing anti-tumor efficacy. Its mechanism of action exhibits multi-target synergistic characteristics:DPD inhibition kinetics:The binding constant Ki=0.28 μ M between Gimoste and DPD active site exhibits competitive inhibitory effect. Enzyme kinetics studies have shown that in the presence of gemostat, the Vmax of DPD decreases by 67%, the Km value increases.
Enhanced effect of fluorouracil:Preclinical experiments have shown that the combination of gemostat can increase the concentration of 5-FU in tumor tissue by 3.2-5.8 times and prolong the duration of action to 48 hours.
This pharmacokinetic optimization directly translates into enhanced drug efficacy, and in vitro experiments have shown that the IC50 value for gastric cancer cell lines decreased from 12.4 μ M for 5-FU alone to 3.1 μ M.by 4.1 times, and the metabolic clearance rate of 5-FU is significantly altered.

Clinical indications and standard treatment plan
Treatment of gastrointestinal tumors-Gastric cancer: As the core component of Tegio capsule (TS-1), gemostat combined with tegafur and ateiracile is used for first-line treatment of advanced gastric cancer. The JCOG9912 trial showed that the median survival time of the Tegio group was 12.5 months, which was better than the 10.1 months of the 5-FU monotherapy group.Colorectal cancer: As a DPD modulator in the FOLFOXIRI regimen, combined with irinotecan and oxaliplatin, phase III studies have shown an objective response rate (ORR) of 65%, which is 18% higher than traditional regimens.
Application of pancreatic cancer-In the combination therapy of gemcitabine and tigio (GS therapy), gemcitabine enhances the synergistic effect by maintaining an effective concentration of 5-FU. The Japanese GEST study confirmed that the 1-year survival rate of locally advanced pancreatic cancer increased from 42% to 63%.Exploration of other solid tumors:In phase II clinical trials of breast cancer and non-small cell lung cancer, gemcitabine combined with capecitabine showed a disease control rate (DCR) of 72%, especially for patients with high DPD activity.
Drug combination strategy and synergistic mechanism
Collaborative design of Tigio capsules-Tigafur (FT): As a prodrug of 5-FU, it is converted into an active ingredient under the action of liver microsomal CYP2A6.Oxo: distributed in the intestinal mucosa, selectively inhibits orotate phosphoribosyltransferase (OPRT) and reduces intestinal toxicity.Jimost: Maintaining plasma 5-FU concentration through DPD inhibition, achieving a balance between efficacy and toxicity.
Example of Combination Chemotherapy Protocol-S-1+Cisplatin (SP regimen): In neoadjuvant chemotherapy for gastric cancer, the ORR reaches 58% and the pathological complete response rate (pCR) is 12%, significantly better than the ECF regimen.
S-1+paclitaxel: For HER2 negative gastric cancer, the median progression free survival (PFS) reported in phase I/II studies is 6.8 months, which is better than the 4.2 months of paclitaxel monotherapy.

Individualized drug delivery strategy:
Predicting enzyme activity by detecting DPD gene polymorphism (such as 2A/2A type) in patients, and guiding the adjustment of Giemster dosage.
The UMIN000002345 experiment showed that the incidence of grade III-IV toxicity in the genotype group decreased from 42% to 23%.
For advanced esophageal cancer, Tegio can significantly improve swallowing difficulties and increase the quality of life score (EORTC QLQ-OES18) by 27 points, which is superior to optimal supportive treatment.

Application in special clinical scenarios

Treatment of elderly tumors
For patients aged 75 years or older, the dose of Tegio is adjusted to 40mg/m ² bid, and Gimostat compensates for metabolic slowdown by prolonging the action time of 5-FU.
The JGCOG1213 study confirmed that the efficacy of this regimen is equivalent to the standard dose in elderly patients with advanced gastric cancer, but the incidence of neutropenia is reduced by 15%.
Application of Conversion Therapy:
In liver metastasis of colorectal cancer, the combination of Tegio and Bevacizumab is used as a translational chemotherapy regimen, while Gismost promotes tumor regression by maintaining drug exposure. A retrospective study showed that the R0 resection rate increased from 18% to 34%.
The value of palliative care

Frontier applications in drug research and development
New prodrug design template
Develop dual functional prodrug molecules by utilizing the DPD inhibitory properties of Gimeracil. For example, by connecting Giemster with topoisomerase inhibitors through cleavable linkers, tumor microenvironment responsive drug release can be achieved.
Nano drug delivery system:Co loading Gimostat and 5-FU onto mesoporous silica nanoparticles (MSN) enhances tumor targeting through EPR effect. Animal experiments showed that the drug concentration at the tumor site increased by 6.8 times, and the cardiotoxic indicator troponin I level decreased by 45%.
Exploration of immune combination therapy:
Jimost enhances M1 polarization of tumor associated macrophages (TAMs) by prolonging the action time of 5-FU, and when combined with PD-1 inhibitors, it can increase cytotoxic T lymphocyte infiltration. The preclinical model showed that the tumor growth inhibition rate of the combination group reached 78%, which was 42% higher than that of the monotherapy group.
Expanding applications in non tumor fields
Antiviral Research:In vitro experiments have found that gemostat has inhibitory effects on Zika virus (ZIKV) NS5 polymerase, with a half maximal inhibitory concentration (IC50) of 12.7 μ M, and shows synergistic antiviral effects when combined with sofosbuvir.
Exploration of antibacterial activity-For drug-resistant Staphylococcus aureus, Gimostat exerts antibacterial effects by inhibiting dihydropteroate synthase (DHPS), with a MIC value of 64 μ g/mL.
Although higher than the clinical drug concentration, it provides a new target for structural optimization.Research on neurodegenerative diseases:
Preliminary studies have shown that gemostat can cross the blood-brain barrier and improve cognitive function in Alzheimer's disease model mice by regulating thymine metabolism.
The specific mechanism is still under investigation.
Analysis of Typical Application Examples
Perioperative treatment of gastric cancer (JCOG1301 trial)
Solution: Ceio 80mg/m ² bid d1-14+Cisplatin 60mg/m ² d8q3w x 3 cycles;Result: R0 resection rate was 83%, 3-year DFS rate was 62%, and compared with the postoperative adjuvant chemotherapy group, it increased by 11%;Toxicity management: By adjusting the dosage of Giemster, the hematological toxicity of grade III or above was reduced from 52% to 38%
Conversion therapy for liver metastasis of colorectal cancer (OPUS study)
Solution: FOLFOXIRI (irinotecan+oxaliplatin+fluorouracil)+gemcitabine 9mg bid.
Neoadjuvant therapy for pancreatic cancer (PREOPANC-1 trial)
Scheme: Gemcitabine 1000mg/m ² d1,8,15+Tegio 30mg/m ² bid d1-28 q4w × 3 cycles;Result: The R0 resection rate was 42%, which was 18% higher than the simple surgery group, and the median OS was prolonged by 6.3 months.
Safety management and medication optimization
Dose adjustment standard
Renal insufficiency: When creatinine clearance rate is less than 50mL/min, the dose of Tegio is reduced by 20%
Liver dysfunction: Child Pugh class B patients with a 35% increase in Gimostat AUC require close monitoring
Toxicity prevention and control strategies
Hematological toxicity: Prophylactic administration of G-CSF (PEG rhG CSF 6mg d2) can reduce the incidence of grade IV neutropenia from 32% to 8%
Gastrointestinal reactions: Combined with the triple antiemetic regimen of aripipitan, the incidence of CINV decreased from 68% to 41%;Drug interactions;CYP2A6 inhibitors (such as ciprofloxacin): increase the conversion of tegafur and require monitoring of 5-FU related toxicity.
Future development direction
Development of biomarkers-Establish a rapid detection kit for DPD activity, based on the ratio of uracil/dihydrouracil in patient urine to guide personalized medication. Currently, a prototype product has entered the clinical trial stage.Intelligent drug delivery system:Developing pH sensitive nanoparticles and utilizing the pH gradient of the tumor microenvironment to achieve programmed release of gemcitabine at the tumor site.

Gimeracil, as a competitive and reversible inhibitor of DPD and a modulator of DNA repair pathways, holds great promise in cancer research and therapy. Its ability to enhance the efficacy of 5-FU-based chemotherapy and radiation therapy, along with its relatively favorable safety profile, makes it a valuable addition to the armamentarium of anticancer agents.
Ongoing clinical trials and future research efforts will further elucidate its role in different cancer types and treatment settings.


Potentially leading to improved treatment outcomes and better quality of life for cancer patients.
As our understanding of the molecular mechanisms underlying cancer development and progression continues to deepen, it may find even broader applications in personalized cancer therapy, offering new hope in the fight against this devastating disease.
Frequently Asked Questions
What is the use of this drug?
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Gimeracil is used as an adjunct to antineoplastic therapy. When used within the product Teysuno, gimeracil is indicated for the treatment of adults with advanced gastric (stomach) cancer when given in combination with cisplatin.
What are the side effects of Tegafur oteracil?
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In some cases, Tegafur+gimeracil+oteracil may cause side effects such as nausea, vomiting, diarrhoea, and constipation. Do not be reluctant to talk with your doctor if any of the side effects persist or worsen.
Will I lose my hair with gemcitabine?
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Hair loss. On its own, gemcitabine can cause hair thinning. However, when it's given with carboplatin or paclitaxel, most people will lose all their hair, including eyebrows, eyelashes and other body hair. Scalp cooling may prevent or reduce hair loss.
Can gemcitabine shrink tumors?
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Giving gemcitabine, docetaxel, and radiation therapy to patients with soft tissue sarcoma of the extremities may lead to a reduction in the size of the tumor prior to surgery. It may also lead to better surgical outcomes and/or reduce the risk of the tumor spreading to other parts of the body.
What cancers does gemcitabine treat?
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Gemcitabine is a chemotherapy medication that treats breast cancer, lung cancer, pancreatic cancer and ovarian cancer. A healthcare provider will give you this injection via infusion into a vein at a hospital or clinic.
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