A-Z Drug Facts > Trimetrexate Glucuronate

Trimetrexate Glucuronate

Pronouncation: (TRY-meh-TREK-sate glue-CURE-uh-nate)
Class: Folate antagonist

Trade Names:
Neutrexin
- Powder for injection, lyophilized 25 mg

Pharmacology

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Inhibits dihydrofolate reductase necessary for DNA, RNA, and protein synthesis, leading to cell death. Following a single-dose of 10 to 130 mg/m ² the alpha phase t _½ was about 57 min followed by a terminal phase with a t _½ of approximately 16 h. Cl has been reported as about 53 mL/min and about 32 mL/min following single-dose administration.

Pharmacokinetics

Distribution

There are inconsistencies in reporting of protein binding; in vitro, trimetrexate is 95% protein bound (over concentration of 18.75 to 100 ng/mL). Others report greater than 98% bound at concentrations 0.1 to 10 mcg/mL. Vd in AIDS patients is approximately 20 L/m ² .

Metabolism

Metabolism has not been characterized. Preclinical trial suggest major metabolic pathway is oxidative O-demethylation followed by conjugation to either glucuronide or the sulfate.

Elimination

Terminal t _½ in HIV is approximately 11 h and terminal t _½ in cancer is approximately 16 h. Cl is approximately 38 mL/min/m ² .

Indications and Usage

As alternative therapy, with concurrent leucovorin administration, for treatment of moderate-to-severe Pneumocystis carinii pneumonia in immunocompromised patients in whom trimethoprim-sulfamethoxazole cannot be used.

Unlabeled Uses

Treatment of non-small cell lung, prostate, and colorectal cancer.

Contraindications

Clinically significant sensitivity to trimetrexate, leucovorin, or methotrexate.

Dosage and Administration

Adults

IV 45 mg/m ² daily by IV infusion over 60 to 90 min for 21 days. Leucovorin may be administered IV at dose of 20 mg/m ² over 5 to 10 min every 6 h for total daily dose of 80 mg/m ² or PO at dose of 20 mg/m ² every 6 h for 24 days. Adjust dose of trimetrexate and leucovorin according to hematologic toxicity. Interruption of therapy may be necessary for hematologic, hepatic, renal, or mucosal toxicity or for uncontrolled fever. See manufacturer's recommendations.

Storage/Stability

Store vials at controlled room temperature and protect from exposure to light. After reconstitution, retain solution at room temperature or under refrigeration for up to 24 h. Do not freeze reconstituted solution.

Drug Interactions

Hepatic enzyme inducers (eg, phenobarbital, phenytoin, carbamazepine, rifampin, rifabutin)

Decreased trimetrexate concentrations and reduced efficacy are possible.

Hepatic enzyme inhibitors (eg, ketoconazole, itraconazole, macrolides, cimetidine)

Increased trimetrexate concentrations and increased toxicity are possible.

Hepatotoxic drugs (eg, NSAIDs, etretinate, ethanol, methotrexate, asparaginase)

Increased risk of hepatotoxicity may occur.

Nephrotoxic drugs (eg, aminoglycosides, amphotericin B, cisplatin, co-trimoxazole, cyclosporine, ganciclovir, melphalan, NSAIDs)

Increased risk of nephrotoxicity may occur.

Pneumococcal vaccine

Reduced vaccine efficacy may occur.

Pyrimethamine, trimethoprim

Increased antifolate effects and increased toxicity may occur.

Yellow fever vaccine, other live vaccines

Increased risk of infection (ie, vaccine toxicity).

Zidovudine

Zidovudine should be discontinued during trimetrexate therapy to allow for full therapeutic doses of trimetrexate.

Incompatibility

Do not mix with solutions containing either chloride ion (eg, sodium chloride) or leucovorin, because precipitation occurs instantly.

Laboratory Test Interactions

None well documented.

Adverse Reactions

CNS

Confusion; fatigue.

Dermatologic

Rash; pruritus.

GI

Nausea; vomiting; increased serum transaminases; increased alkaline phosphatase; increased bilirubin; mucositis; hepatotoxicity.

Genitourinary

Increased serum creatinine.

Hematologic

Neutropenia; thrombocytopenia; anemia; myelosuppression.

Metabolic

Hyponatremia; hypocalcemia.

Miscellaneous

Fever.

Precautions

Warnings Concurrent leucovorin must be used to avoid potentially serious or life-threatening toxicities including bone marrow suppression, oral and GI mucosal ulceration, and renal and hepatic dysfunction.

Pregnancy

Category D .

Lactation

Undetermined.

Children

Safety and efficacy not established.

Hypersensitivity

Has rarely occurred.

Renal Function

Use drug with caution in patients with impaired renal function.

Hepatic Function

Use drug with caution in patients with impaired hepatic function.

Special Risk Patients

Use drug with caution in patients with impaired hematologic function and in patients who require concomitant therapy with nephrotoxic, myelosuppressive, or hepatotoxic drugs.

Hepatic toxicity

Transient elevations of transaminases and alkaline phosphatase have occurred. Interrupt therapy if levels increase to more than 5 times ULN.

Seizures

Have rarely occurred.

Overdosage

Symptoms

Severe neutropenia, severe thrombocytopenia, severe anemia, nausea, vomiting.

Patient Information

• Explain that continued, frequent monitoring by health care provider is necessary.
• Inform patient that blood test must be performed at least twice weekly.
• Explain that leucovorin therapy must be continued for at least 72 h after last dose of trimetrexate.
• Describe potential adverse reactions, and what should be reported to health care provider (eg, fever, mucosal toxicity).

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