Primsol (trimethoprim)

  • Pharmacy Author:
    Omudhome Ogbru, PharmD

    Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.

  • Medical and Pharmacy Editor: Jay W. Marks, MD
    Jay W. Marks, MD

    Jay W. Marks, MD

    Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

What is Primsol (trimethoprim) and how does it work?

Primsol is a synthetic (man-made) antibiotic that interferes with the production of tetrahydrofolic acid, a chemical that is necessary in order for bacteria and human cells to produce proteins. Trimethoprim inhibits production of tetrahydrofolic acid by inhibiting the enzyme responsible for making tetrahydrofolic acid from dihydrofolic acid. Primsol inhibits the bacterial enzyme more than the human enzyme. Therefore, Primsol has less effect on the production of tetrahydrofolic acid by humans. Because of the frequent development of resistance to Primsol, it is more effective when combined with another antibiotic, sulfamethoxazole (Azo-Gantanol), and is rarely used alone.

What brand names are available for XYZ?

  • Primsol is the brand name for trimethoprim  available in the US.
  • Trimpex and Proloprim are brand names that have been discontinued in the US.

Is Primsol (trimethoprim) available as a generic drug?

Yes

Do I need a prescription for Primsol (trimethoprim)?

Yes

What are the uses for Primsol (trimethoprim)?

  • Primsol is used for the treatment of uncomplicated urinary tract infections (UTI) due to susceptible bacteria such as Escherichia coli, Proteus mirabilis, Klebsiella pneumoniae, Enterobacter species, and coagulase-negative Staphylococcus species, including S. saprophyticus.

What are the side effects of Primsol (trimethoprim)?

The most common side effects associated with Primsol involve the gastrointestinal (GI) tract, such as:

Other important side effects are:

Rarely, the skin rash can progress to peeling or blistering. Some patients have photosensitivity reactions, that is, they develop skin rashes on parts of their body that are exposed to the sun.

Serious side effects include:

Primsol may cause anemia due to a deficiency of folic acid. The anemia usually is mild and resolves when the Primsol is stopped. Patients who are folate-deficient, such as malnourished, alcoholic, geriatric, or pregnant females, may be at greater risk for developing anemia with Primsol. Warning signs of anemia include white or bluish fingernails and unusual tiredness and weakness. Prolonged therapy can result in low platelet counts, low white blood cell counts, and other toxic effects on the blood cells.

Medically Reviewed by a Doctor on 11/18/2016

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