Trimethoprim

Trimethoprim is an antibiotic drug employed in the prevention and treatment of bacterial infections in the urinary tract and is particularly effective in treating cystitis.. The medicine is also used in the bacterial infection treatments of the respiratory tract and lungs. This bacteriostatic drug belongs to the family of dihydrofolate reductase inhibitors. The medicine is available both in the form of suspension and tablets.

Trimethoprim for cystitis

Alternative Names

Formerly, the drug was marketed by GlaxoSmithKline under the various trade names such as Triprim, Proloprim and Monotrim. Clinically, the drug is called TMP or TRI. The laboratory abbreviation for the antibiotic is W.

 

How Trimethoprim works?

Bacteria needs to grow and multiply after infecting a certain region. So, in order to do that, they must synthesize DNA for which they need Folic acid or Folate. However, since Trimethoprim inhibits the synthesis of folate by the bacteria, they cannot produce the DNA either and hence, are prevented from multiplying in number. This stops the infection from spreading further. Eventually, the bacteria are destroyed by the body’s immune system.  To confirm the infection causing bacteria is susceptible to the antibiotic, the physician may take a tissue from the infected region and culture it in the laboratory conditions.

 

Caution

The medicine is to be used with caution by

  • Newly born babies
  • Elderly people
  • People with decreased kidney function
  • Those in the risk groups of folic acid deficiency
  • People with hereditary blood disorders (porphyrias)

The medicine is strictly not to be used in the following cases –

  • The number of blood cells in your blood keeps fluctuating.
  • You are in the first trimester of pregnancy.
  • If you are allergic to one or more ingredients used in the medicine.

It may also be used for treating travelers' diarrhea.

 

Trimethoprim Dosage

The medicine is prescribed to be taken once to twice a day, as prescribed by the doctor. It may or not be taken with food. Commonly, doctors advise that the medicine be taken an hour or two before or after meals. However, for patients who may experience nausea following this routine, they make take the drug with food. Also, for the medicine to function most effectively, it is recommended that the patient treats himself to minimum eight glasses of liquid every day, which may range from water, coffee, tea and soft drinks to fruit juice and milk. If a dose is missed, it should be taken as soon as remembered. However, it may be skipped if it is almost time for the next dose. Double dosing should be avoided at all costs.

 

Precautions

Before taking the drug, it is important to let the doctor know in case of the following –

  • You have allergy to sulfa drugs, Trimethoprim, oral diabetes drugs, diuretics or other drugs.
  • You are on other medications as well, especially vitamins and Phenytoin.
  • You have kidney or liver disease or anemia.
  • You are planning for pregnancy or already are pregnant or a nursing mother.

 

Side Effects of Trimethoprim

Some side effects which may affect the patients include –

  • vomiting
  • upset stomach
  • diarrhea
  • rash (hives)
  • itching
  • sore throat
  • Chills or fever
  • mouth sores
  • unusual bleeding or bruising
  • yellowing of eyes or skin
  • difficulty swallowing or breathing
  • paleness
  • joint aches
  • bluish-colored lips, skin or fingernails

 

Reaction with Other Medicines

Your kidney may become susceptible to side effects if you take Trimethoprim along with ciclosporin. On the other hand, if the drug is taken with antimalarial pyrimethamine, it may result in the lowering of the folic acid levels in the blood. This may lead to folate deficiency anaemia or interfere with blood cell production. Some other medicines which may cause side effects in the body in combination with Trimethoprim, include -

  • phenytoin
  • procainamide
  • dapsone
  • digoxin
  • methotrexate
  • clozapine
  • azathioprine
  • mercaptopurine
  • warfarin

 

StoringTrimethoprim

  • The medicine is best stored in the container it is sold in.
  • It should be kept out of reach of children.
  • It needs to be kept at room temperature, unexposed to extreme heat and excess moisture.
  • The medicine should not be stored in the bathroom.

 

Points to Remember

  • Unless advised otherwise by the doctor, its recommended to complete the prescribed course of this antibiotic, even if it may feel that you are recovering or the infection has visibly cleared up.
  • Stopping the dosage abruptly may bring back the infection and in some cases, the repeat infection may cause the bacteria to become immune to the antibiotic.
  • In rare cases, the drug may trigger a lowering of the blood cell count in your blood, the symptoms of which may appear as purple spots on skin, bleeding or bruising, sore throat, fever, general illness, mouth ulcers or fatigue. If such a thing happens, it is advised that you seek immediate medical attention.