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Hair Loss
Erectile Dysfunction
FAQ

Dutasteride Safety Information

Brand Names in Canada

  1. Avodart

Important Notes

  • Women who are pregnant or may become pregnant should not handle dutasteride, as it can cause harmful effects on a fetus. Studies in animals or pregnant women have demonstrated positive evidence of fetal abnormalities.
  • Dutasteride is detectable in semen, however the effect on fertility and pregnancy is unknown. If you are trying to conceive or if you have a pregnant spouse, we recommend you do not take this medication due to fertility and teratogenic concerns. If you are taking this medication and unexpectantly concieve, you should consider using barrier contraception (condoms) and/or stop taking the medication.

What is Dutasteride?

Dutasteride 0.5mg, manufactured by GlaxoSmithKline, became available for the treatment of prostate enlargement (benign prostatic hypertrophy or BPH) in North America in January 2003 under the trade name Avodart. In 2006, Dutasteride 0.5mg became available in Canada in a generic formulation. Dutasteride 0.5mg is Health Canada authorized for the treatment BPH, but not for hair loss.

Dutasteride is an oral medication that blocks the conversion of testosterone to dihydrotestosterone (DHT), the hormone largely responsible for prostate enlargement and for male pattern baldness. It does this by inhibiting the action of both types (Type I and II) 5-alpha reductase enzyme. In contrast, finasteride, the Health Canada authorized medication for hair loss, inhibits only the Type II enzyme, the enzyme that is present in highest concentrations in and around the hair follicles.

Both dutasteride and finasteride produce a rapid decrease in serum DHT concentration. Lowering DHT appears to inhibit the miniaturization (shrinking) of affected hair follicles and helps restore miniaturized hair follicles to regrow visible hair.

Dutasteride (Avodart) inhibits both type I and type II, 5a-reductase. At the 0.5-mg dose, it is about 3 times as potent as finasteride at inhibiting type II, 5α-reductase enzyme and more than 100 times as potent at inhibiting the type I 5α-reductase enzyme. Type I receptors inhibited by dutasteride are present in other organs of the body besides the skin, including the liver and kidneys.

It is important to have realistic expectations when taking dutasteride for hair loss, as it will not regrow all your hair back. The effects of dutasteride are confined to areas of the scalp that are thinning, but where there is still some hair present. It does not grow hair in areas that are completely bald. Although it can regrow hair in thin areas, the major benefit of dutasteride seems to be in its ability to slow down or halt hair loss.

This medicine is available only with your doctor’s prescription.

This product is available in the following dosage forms:

  • Capsule, Liquid Filled

Before Using

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

Dutasteride is not indicated for use in the pediatric population. Safety and efficacy have not been established.

Geriatric

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of dutasteride in the elderly.

Pregnancy

Women who are pregnant or may become pregnant should not handle dutasteride, as it can cause harmful effects on a fetus. Studies in animals or pregnant women have demonstrated positive evidence of fetal abnormalities. This drug should not be used or handled by women who are or may become pregnant because the risk clearly outweighs any possible benefit.

Dutasteride is detectable in semen, however the effect on fertility and pregnancy is unknown. If you are trying to conceive or if you have a pregnant spouse, we recommend you do not take this medication due to fertility and teratogenic concerns. If you are taking this medication and unexpectantly concieve, you should consider using barrier contraception (condoms) and/or stop taking the medication.

Breastfeeding

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Drug Interactions

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Ceritinib
  • Clarithromycin

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Cimetidine
  • Ciprofloxacin
  • Diltiazem
  • Ketoconazole
  • Ritonavir
  • Verapamil

Other Interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

  • Liver disease—Use with caution. The effects may be increased because of slower removal of the medicine from the body.

Proper Use

Take this medicine only as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered.

You may take this medicine with or without food.

Swallow the capsule whole. Do not crush, chew, or open it. The contents of the capsule may irritate your lips, mouth, or throat.

This medicine comes with a patient information leaflet. Read and follow these instructions carefully. Ask your doctor if you have any questions.

Dosing

The dose of this medicine will be different for different patients. Follow your doctor’s orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

For oral dosage form (capsules):

  • For male pattern hair loss:
    • Adults—0.5 milligram (mg) once a day.
    • Children—Use is not recommended.

Missed Dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Precautions

It is very important that your doctor check you at regular visits to make sure that this medicine is working properly and to check for any unwanted effects that may be caused by this medicine.

Women and children should not use this medicine. Pregnant women or women who may become pregnant should not handle or touch the capsules. Dutasteride can be absorbed through the skin and can cause birth defects in male fetuses. If a pregnant woman does come in contact with this medicine, the affected area should be washed right away with soap and water, especially if the capsule is broken.

Men who have taken this medicine should not donate blood until 6 months have passed since the last dose. Dutasteride can remain in your blood for a long time and be passed on to a pregnant woman who receives a blood transfusion.

This medicine may increase your risk of developing high-grade prostate cancer. Tell your doctor if you have concerns about this risk.

This medicine may affect the results of the prostate specific antigen (PSA) test, which may be used to detect prostate cancer. Make sure you tell all of your doctors that you are using this medicine.

This medicine does not usually affect normal sexual abilities for most men. You may notice that you ejaculate less fluid when you have sex.

Side Effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

Rare

  • Chest pain or discomfort
  • dilated neck veins
  • extreme fatigue
  • irregular breathing
  • irregular heartbeat
  • shortness of breath
  • swelling of the face, fingers, feet, or lower legs
  • weight gain
  • wheezing

Incidence not known

  • Blistering, flaking, or peeling of the skin
  • cough
  • difficulty with swallowing
  • dizziness
  • fast heartbeat
  • hives or welts
  • itching skin
  • large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • redness of the skin
  • skin rash
  • tightness in the chest
  • unusual tiredness or weakness
  • wheezing

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common

  • Abnormal ejaculation
  • decreased interest in sexual intercourse
  • decreased sexual performance or desire
  • impotence
  • inability to have or keep an erection
  • loss in sexual ability, desire, drive, or performance
  • pain, soreness, swelling, or discharge from the breast or breasts

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.


Portions of this document last updated: August 01, 2019

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