Generic Name: Trimetrexate Brand Name(s): Trimetrexate.


What is Trimetrexate used for?

Trimetrexate is commonly used for treating moderate to severe Pneumocystis carinii pneumonia (PCP) in patients with weak immune systems, including those with AIDS, who are not able to take the standard treatment. Trimetrexate is used in combination with leucovorin.

Trimetrexate is an anti-infective agent. It works by inhibiting DNA, RNA, and protein synthesis, leading to cell death.

How should I take Trimetrexate?

Use trimetrexate as directed by your doctor. Check the label on the medicine for exact dosing instructions.

Trimetrexate is usually administered as an injection at your doctor’s office, hospital, or clinic. If you are using trimetrexate at home, carefully follow the injection procedures taught to you by your health care provider.

Trimetrexate should not be given at the same time as fluorouracil. Doses should be separated as directed.

If trimetrexate contains particles or is discolored, or if the vial is cracked or damaged in any way, do not use it.

Trimetrexate must be used with another medicine, leucovorin, as protection against potentially serious or life-threatening reactions. Treatment with leucovorin must extend 72 hours past the last dose of trimetrexate. Use all leucovorin doses as instructed. If you fail to use the correct dose and all doses of leucovorin, it may cause fatal toxicity.

Keep this product, as well as syringes and needles, out of the reach of children and away from pets. Do not reuse needles, syringes, or other materials. Dispose of properly after use. Ask your doctor or pharmacist to explain local regulations for proper disposal.

If you miss a dose of trimetrexate, contact your doctor immediately.

How do I store Trimetrexate?

Trimetrexate is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store Trimetrexate in the bathroom or the freezer. There may be different brands of Trimetrexate that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush Trimetrexate down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Precautions & warnings

What should I know before using Trimetrexate?

Before using this drug, tell your doctor if:

  • You are pregnant or breastfeeding. This is because, while you are expecting or feeding a baby, you should only take medicines on the recommendation of a doctor.
  • You are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines.
  • You have allergy with any of active or inactive ingredients of Trimetrexate or other medications.
  • You have any other illnesses, disorders, or medical conditions.
  • You are taking a nonsteroidal anti-inflammatory drug (NSAID) (e.g., ibuprofen) or pristinamycin.
  • You have bone marrow depression, a blood disorder, or kidney or liver problems.

Do not drink alcohol while you are using trimetrexate.

Trimetrexate may reduce the number of clot-forming cells (platelets) in your blood. To prevent bleeding, avoid situations in which bruising or injury may occur. Report any unusual bleeding, bruising, blood in stools, or dark, tarry stools to your doctor.

Trimetrexate may lower your body’s ability to fight infection. Prevent infection by avoiding contact with people with colds or other infections. Notify your doctor of any signs of infection including fever, sore throat, rashes, or chills.

Lab tests, including neutrophil counts, platelet counts, liver function, and kidney function, may be performed to monitor your progress or to check for side effects. Be sure to keep all doctor and lab appointments.

Use trimetrexate with caution in the elderly because they may be more sensitive to its effects.

Trimetrexate is not recommended for use in children. Safety and effectiveness have not been confirmed.

Is it safe during pregnancy or breastfeeding? 

There isn’t enough information about the safety of using Trimetrexate during pregnancy and breastfeeding. Please always consult with your doctor to weigh the potential benefits and risks before taking Trimetrexate.

Side effects

What side effects can occur from Trimetrexate?

Check with your doctor if any of these most common side effects persist or become bothersome:

  • Confusion
  • Fatigue

Seek medical attention right away if any of these severe side effects occur:

  • Severe allergic reactions (rash; hives; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue)
  • Chills
  • Drops in counts of blood cells
  • Fever
  • Itching
  • Nausea
  • Sores in mouth
  • Symptoms of a new infection
  • Unusual bruising or bleeding
  • Unusual tiredness or weakness
  • Vomiting
  • Yellow discoloration of skin or eyes.

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side-effect, please consult your doctor or pharmacist.


What drugs may interact with Trimetrexate?

Trimetrexate may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

Products that may interact with this drug are:

  • Cisplatin, corticosteroids (e.g., prednisone), cyclosporine, etretinate, NSAIDs (e.g., ibuprofen), penicillins (e.g., amoxicillin), pristinamycin, probenecid, quinolones (e.g., ciprofloxacin), salicylates (e.g., aspirin), sulfonamides (e.g., sulfamethoxazole), tetracyclines (e.g., doxycycline), or trimethoprim because the actions and side effects of trimetrexate may be increased, possibly leading to toxicities.
  • Digoxin or hydantoins (e.g., phenytoin) because the effectiveness of these medicines may be decreased.

Does food or alcohol interact with Trimetrexate?

Trimetrexate may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with Trimetrexate?

Trimetrexate may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have.


The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using Trimetrexate.

What is the dose of Trimetrexate for an adult?

Consult your doctor for further information.

What is the dose of Trimetrexate for a child?

The dosage has not been established in pediatric patients. It may be unsafe for your child. It is always important to fully understand the safety of the drug before using. Please consult with your doctor or pharmacist for more information.

How is Trimetrexate available?

Trimetrexate is available in the following dosage forms and strengths:

  • Injection

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of Trimetrexate, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.


Hello Health Group does not provide medical advice, diagnosis or treatment.


Review Date: November 28, 2017 | Last Modified: November 28, 2017

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