Trimpex Side Effects

Generic name: trimethoprim

Note: This document contains side effect information about trimethoprim. Some of the dosage forms listed on this page may not apply to the brand name Trimpex.

Some side effects of Trimpex may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

For the Consumer

Applies to trimethoprim: oral solution, oral tablet

Get emergency medical help if you have any of these signs of an allergic reaction while taking trimethoprim (the active ingredient contained in Trimpex) hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have a serious side effect such as:

• fever, chills, body aches, flu symptoms, sores in your mouth and throat;

• pale skin, easy bruising, unusual bleeding (nose, mouth, vagina, or rectum), purple or red pinpoint spots under your skin;

• high potassium (slow heart rate, weak pulse, muscle weakness, tingly feeling); or

• severe headache with muscle cramps, confusion, weakness, loss of coordination, feeling unsteady, and weak or shallow breathing.

Other common side effects may include:

• stomach pain, vomiting, diarrhea;

• sore or swollen tongue; or

• mild itching or skin rash.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.

For Healthcare Professionals

Applies to trimethoprim: compounding powder, oral solution, oral tablet

Dermatologic

Common (1% to 10%): Rash (up to 6.7%)
Rare (less than 0.1%): Stevens-Johnson syndrome, exfoliative dermatitis, erythema multiforme, toxic epidermal necrolysis (Lyell syndrome)
Frequency not reported: Pruritus, phototoxic skin eruptions

The incidence of rash was 2.9% to 6.7% at recommended doses of 200 mg/day.

A higher incidence of rash was reported in clinical trials using large doses of trimethoprim. These rashes had an onset of 7 to 14 days after begin of therapy and were maculopapular, morbilliform, pruritic, and mild to moderate in severity.

One case report described Stevens-Johnson syndrome, arthritis, and uveitis associated with trimethoprim.

Hypersensitivity

Common (1% to 10%): Diffuse, often pruritic, maculopapular or urticarial rashes (up to 7%)
Rare (less than 0.1%): Anaphylaxis, diffuse pneumonitis
Frequency not reported: Fixed drug eruption, linear fixed drug eruption

A Dutch retrospective analysis identified 13 cases of probable or possible anaphylaxis with a probable or definite causal relationship to trimethoprim.

Gastrointestinal

Rare cases of Clostridium difficile pseudomembranous colitis have been reported during or after trimethoprim (the active ingredient contained in Trimpex) therapy.

Frequency not reported: Epigastric distress, nausea, vomiting, glossitis, Clostridium difficile associated diarrhea, mild abdominal distress, pseudomembranous colitis

Hematologic

Frequency not reported: Leukopenia, megaloblastic anemia, methemoglobinemia, neutropenia, thrombocytopenia

Since trimethoprim inhibits a step of folate synthesis in vivo, megaloblastic anemia was more likely in patients with folate deficiency, such as alcoholics, the malnourished, and in patients with chronic hemolytic anemia.

Metabolic

Frequency not reported: Hyperkalemia, hyponatremia

Renal

Frequency not reported: Increased BUN, increased serum creatinine levels, renal tubular creatinine secretion inhibited, decreased creatinine clearance, aldosterone-antagonistic effect in the renal tubule

Trimethoprim may inhibit renal tubular creatinine secretion, resulting in increased serum levels. Some data indicated a significant decrease in creatinine clearance associated with trimethoprim. These changes appeared to be completely reversible upon discontinuation of therapy.

Trimethoprim acts like amiloride and blocks apical membrane sodium channels in the distal nephron. This resulted in inhibition of potassium secretion and mild hyperkalemia in some cases. Up to 20% of patients with AIDS who were given trimethoprim-sulfamethoxazole developed mild hyperkalemia due to the effect of trimethoprim, not sulfamethoxazole, on the kidney.

Nervous system

Rare (less than 0.1%): Aseptic meningitis

Trimethoprim-induced aseptic meningitis was characterized by a sterile cerebral spinal fluid pleocytosis (usually lymphocytic) associated with meningismus. Trimethoprim-associated aseptic meningitis, like that associated with some nonsteroidal anti-inflammatory medications, may be more likely in patients with underlying connective tissue diseases, such as systemic lupus erythematosus or Sjogren's syndrome. Occult bacterial, viral, and atypical etiologies of meningitis must also be considered. Cases of aseptic meningitis have been reported in AIDS patients.

Hepatic

Rare (less than 0.1%): Cholestatic jaundice
Frequency not reported: Elevated serum transaminases, elevated bilirubin

Other

Frequency not reported: Fever

Musculoskeletal

One case report described Stevens-Johnson syndrome, arthritis, and uveitis associated with trimethoprim (the active ingredient contained in Trimpex)

Rare (less than 0.1%): Arthritis (at least 1 case)

Ocular

One case report described Stevens-Johnson syndrome, arthritis, and uveitis associated with trimethoprim (the active ingredient contained in Trimpex)

Rare (less than 0.1%): Uveitis (at least 1 case)

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