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Active ingredient: Gemcitabine - Brands, Medical Use, Clinical Data

Brands, Medical Use, Clinical Data

Drug Category

  • Radiation-Sensitizing Agents
  • Immunosuppressive Agents
  • Antivirals
  • Antimetabolites
  • Antineoplastic Agents

Dosage Forms

  • Lyophilized powder for injection

Brands / Synonyms

DDFC; DFDC; Gemcin; Gemcitabina [Inn-Spanish]; Gemcitabine HCl; Gemcitabine hydrochloride; Gemcitabinum [Inn-Latin]; Gemtro; Gemzar; Gemzar ; GEO

Indications

For the first-line treatment of patients with metastatic breast cancer, locally advanced (Stage IIIA or IIIB), or metastatic (Stage IV) non-small cell lung cancer and as first-line treatment for patients with adenocarcinoma of the pancreas.

Pharmacology

Gemcitabine is an antineoplastic anti-metabolite. Anti-metabolites masquerade as purine or pyrimidine - which become the building blocks of DNA. They prevent these substances becoming incorporated in to DNA during the "S" phase (or DNA synthesis phase of the cell cycle), stopping normal development and division. Gemcitabine blocks an enzyme which converts the cytosine nucleotide into the deoxy derivative. In addition, DNA synthesis is further inhibited because Gemcitabine blocks the incorporation of the thymidine nucleotide into the DNA strand.

Mechanism of Action

Gemcitabine inhibits thymidylate synthetase, leading to inhibition of DNA synthesis and cell death. Gemcitabine is a prodrug so activity occurs as a result of intracellular conversion to two active metabolites, gemcitabine diphosphate and gemcitabine triphosphate by deoxycitidine kinase. Gemcitabine diphosphate inhibits ribonucleotide reductase, the enzyme responsible for catalyzing synthesis of deoxynucleoside triphosphates required for DNA synthesis. Gemcitabine triphosphate (diflurorodeoxycytidine triphosphate) competes with endogenous deoxynucleoside triphosphates for incorporation into DNA.

Absorption

100%

Toxicity

Myelosuppression, paresthesias, and severe rash were the principal toxicities, LD50=500 mg/kg (orally in mice and rats)

Biotrnasformation / Drug Metabolism

Transformed via nucleoside kinases to two active metabolites, gemcitabine diphosphate and gemcitabine triphosphate. Can also undergo deamination via cytidine deaminase to an inactive uracil metabolite (dFdU).

Contraindications

Gemzar is contraindicated in those patients with a known hypersensitivity to the drug (see Allergic under ADVERSE REACTIONS).

Drug Interactions

No specific drug interaction studies have been conducted. For information on the pharmacokinetics of Gemzar and cisplatin in combination, see Drug Interactions under CLINICAL PHARMACOLOGY section.

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