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  • Trimethoprim: Drug Information

    Trimethoprim is an antibiotic medication primarily used to treat and prevent urinary tract infections (UTIs), including cystitis. In some cases, trimethoprim may also be prescribed to treat other types of infections such as chest infections and acne. It works by inhibiting the production of dihydrofolate reductase, an enzyme necessary for the production of nucleic acids in bacteria, ultimately preventing bacterial growth and replication. See our selection of trimethoprim impurities in our catalog.

    What is trimethoprim?

    Trimethoprim is an antibiotic that is commonly used to treat bacterial infections. It works by inhibiting the production of a key enzyme in the folic acid pathway that is necessary for bacterial growth and replication. Trimethoprim is usually used in combination with other antibiotics, such as sulfamethoxazole, to increase its effectiveness against a wider range of bacteria.

    Trimethoprim is commonly used to treat urinary tract infections, respiratory infections, and other bacterial infections. It is available in various forms, including tablets, capsules, and oral suspension. As with all antibiotics, it is important to take trimethoprim as prescribed by your healthcare provider and to complete the full course of treatment to ensure that the infection is fully cleared.

    How does trimethoprim work?

    Trimethoprim works by inhibiting the production of an enzyme called dihydrofolate reductase which is necessary for the synthesis of tetrahydrofolate, a key precursor in the synthesis of nucleic acids (DNA and RNA) in bacteria. This inhibition of dihydrofolate reductase disrupts the folate pathway in bacteria, leading to a decrease in the production of nucleic acids, which ultimately inhibits bacterial growth and replication.

    Trimethoprim is selective for bacterial dihydrofolate reductase and has little effect on the human enzyme, which means it can target bacterial cells while minimizing harm to human cells. However, it should still be used with caution and under the guidance of a healthcare provider, as with any antibiotic, to minimize the risk of developing antibiotic resistance and to ensure that the infection is treated effectively.

    What are the common side effects of trimethoprim?

    Common side effects of trimethoprim include:

    • Nausea and vomiting
    • Diarrhea or constipation
    • Loss of appetite
    • Headache
    • Dizziness
    • Rash or itching
    • Swollen or sore tongue
    • Joint pain
    • Increased sensitivity to sunlight

    If you experience any of these side effects, you should speak to your healthcare provider. They may recommend changes to your dosage or medication regimen, or they may prescribe additional medication to help manage your symptoms.

    In rare cases, trimethoprim can cause more serious side effects, such as anemia, liver damage, or a severe allergic reaction. If you experience any of the following symptoms, you should seek medical attention immediately:

    • Yellowing of the skin or eyes
    • Dark urine or pale stools
    • Unusual tiredness or weakness
    • Fever or chills
    • Difficulty breathing
    • Swelling of the face, lips, tongue, or throat

    It is important to always follow the instructions provided by your healthcare provider and to report any side effects that you experience.

    What medication should not be taken with trimethoprim?

    There are several medications that should not be taken with trimethoprim or that may require dose adjustments or close monitoring when taken together. These include:

    1. Warfarin: Trimethoprim can increase the anticoagulant effects of warfarin, which can increase the risk of bleeding. Patients taking warfarin should have their INR levels closely monitored when taking trimethoprim.
    2. Methotrexate: Trimethoprim can increase the toxicity of methotrexate, which can lead to serious side effects. Patients taking methotrexate should avoid taking trimethoprim, if possible.
    3. Digoxin: Trimethoprim can increase the serum concentration of digoxin, which can lead to toxicity. Patients taking digoxin should have their serum levels closely monitored when taking trimethoprim.
    4. ACE inhibitors or angiotensin receptor blockers (ARBs): Trimethoprim can increase the serum potassium levels in patients taking ACE inhibitors or ARBs, which can lead to hyperkalemia. Patients taking these medications should have their serum potassium levels closely monitored when taking trimethoprim.
    5. Sulfonylureas: Trimethoprim can increase the serum levels of sulfonylureas, which can lead to hypoglycemia. Patients taking sulfonylureas should have their blood glucose levels closely monitored when taking trimethoprim.

    It is important to always inform your healthcare provider of all medications you are taking, including over-the-counter medications and supplements, to avoid any potential interactions or adverse effects.

    Chemical properties of trimethoprim

    Trimethoprim is a white to cream-colored crystalline powder with a molecular weight of 290.3 g/mol. It is soluble in water and slightly soluble in ethanol and methanol. The chemical name for trimethoprim is 2,4-diamino-5-(3,4,5-trimethoxybenzyl) pyrimidine.

    Trimethoprim is a weak base with a pKa of approximately 7.4, which means it is primarily in the ionized form at physiological pH. It is stable at room temperature but can degrade under conditions of high temperature or humidity. It is typically stored in a dry, cool place away from direct sunlight.

    Trimethoprim is a synthetic antibacterial agent that belongs to the class of diaminopyrimidines. It has a broad spectrum of activity against Gram-positive and Gram-negative bacteria and is commonly used in combination with sulfamethoxazole to increase its effectiveness against a wider range of bacterial infections.

    Conclusion

    In conclusion, trimethoprim is a commonly used antibiotic medication that works by inhibiting the production of dihydrofolate reductase, ultimately preventing bacterial growth and replication. It is primarily used to treat and prevent urinary tract infections, including cystitis, and is sometimes prescribed for other types of infections such as chest infections and acne. Trimethoprim is generally well-tolerated, but common side effects may include nausea, diarrhea, and rash. Patients should always take trimethoprim as prescribed and complete the full course of treatment to ensure the infection is fully cleared. It is also important to inform your healthcare provider of all medications you are taking to avoid any potential interactions or adverse effects.

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