How does this medication work? What will it do for me?

This is a combination product that contains 2 ingredients: trimethoprim and polymyxin b. Both belong to the class of medications called antibiotics. When combined in eye drops, these ingredients are used to treat certain types of eye infections, including conjunctivitis (also known as "pink eye") and blepharitis (irritation along the eye lid). This medication works by killing the bacteria that cause the eye infection.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are using this medication, speak to your doctor. Do not stop using this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

This medication is available as an ophthalmic solution.

How should I use this medication?

The recommended dose for mild-to-moderate infections for adults and children over 2 months of age is to instill 1 or 2 drops in the affected eye every 3 hours (maximum of 6 doses daily) for a period of 7 to 10 days, or as directed by doctor.

For more severe infections, your doctor may instruct you to use 1 or 2 drops in the affected eye(s) every hour until improvement occurs. The dose will then be reduced to 1 or 2 drops every 3 hours. Refer to the package insert and ask your doctor or pharmacist about the proper administration of eye drops.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are using the medication without consulting your doctor.

The following procedure is recommended when using the eye drops:

  1. Wash your hands.
  2. Shake the bottle of eye drops to ensure the liquid is evenly distributed.
  3. Tilt your head back and gently pull the lower eyelid away from the eye to make a pouch under the eye.
  4. Drop the medicine into this space and then let go of the eyelid and gently close your eyes.
  5. Do not blink.
  6. Keep your eyes closed and apply gentle pressure to the inner corner of your eye with your finger for 1 or 2 minutes to prevent excessive absorption into the body.
  7. Wash your hands to remove any of the drops that may have got on them.
  8. Do not touch the dropper or the applicator tip to any surface (including the eye).

Use this medication for the total time period recommended by your doctor, even if you start to feel better. This will reduce the chance of the infection returning and being harder to treat.

It is important to use this medication exactly as prescribed by your doctor. If you miss a dose, use it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not instill a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature (15°C to 25°C) and, protect it from light. Keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not use this mediction if you are allergic to trimethoprim, polymyxin b, or any ingredients of the medication.

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people using this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • temporary burning or stinging, itching, or increased redness upon instillation of eye drops

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • symptoms of an allergic reaction (e.g., lid swelling, itching, increased redness, tearing, or rash)

Stop using the medication and seek immediate medical attention if any of the following occur:

  • signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are using this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Contamination: Avoid contaminating the dropper. Do not touch the dropper to the eye, fingers, or any other surface. This is necessary to maintain the sterility of the drops.

Overgrowth of organisms: Prolonged use of this medication may result in an overgrowth of organisms that are not killed by the medication, including fungi. If your eye gets worse or does not improve in the appropriate time, call your doctor.

Pregnancy: When used correctly, very little of this medication is absorbed into the body. Trimethoprim - polymyxin b may be used during pregnancy if the benefits outweigh the risks.

Breast-feeding: Very little of this medication is absorbed into the body when it is used correctly. It is not known if trimethoprim - polymyxin b passes into breast milk, however this medication may be used while breast-feeding, if the benefit to the mother outweighs the risks to the baby's health.

If you are a breast-feeding mother and are using this medication, talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of this medication for use by children below the age of 2 months have not been established.

What other drugs could interact with this medication?

There may be an interaction between trimethoprim - polymyxin b and any of the following:

  • other eye drops and eye ointments

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.