Avodart (dutasteride)

Avodart Manufactured by: GlaxoSmithKline.

What is Avodart used for?

If you are suffering or ever suffered from benign prostatic hyperplasia (BPH), you may have been prescribed a drug called Avodart (Dutasteride) by your doctor. For those who do not know, Avodart is a drug used to treat BPH, a medical condition characterized by an enlarged prostate in men. The prostate is a gland that surrounds urethra, which is a tube that expels urine from the bladder.  An enlarged prostate squeezes or blocks urethra making it difficult to urinate.

BPH, as the name depicts, is a benign condition but it may cause tremendous inconvenience in some, not all, men. It develops when testosterone, the male sex hormone, is converted into dihydrotestosterone (DHT) by an enzyme called 5-alpha-reductase.

This is where Avodart comes in. It works by blocking the conversion of testosterone into DHT. Avodart works best when given in combination with another drug called Tamsuslion (Flomax), an alpha-blocker. Tamsulosin is a drug that works by improving urination in men through a different mechanism of action.

What is the dosage form and potency (strength) of Avodart?

Avodart comes in the form of soft gelatin capsules with potency 0.5 mg.

What You Should Know About the drug

  • Thoroughly read the medication guide before administering any medicine.
  • Avodart is used for a specific condition that affects men only. Its use is strongly prohibited in women, particularly those who are or planning on becoming pregnant.
  • Immediately discontinue the drug and consult your healthcare provider if you develop any allergic reaction or skin condition.
  • For women and children – Do not handle the drug bare-handedly because it can absorb through your skin and reach your blood. Once in your body, it can lead to dire consequences, such as fetal damage. Avoid exposure in all circumstances. Accidental exposure to a leaky capsule should prompt immediate and thorough washing of hands with a soap.
  • The capsule should be swallowed with water.  Do not chew the capsules, it can cause irritation of the lining of mouth and pharynx.
  • You can take the drug on empty or full stomach, even when you are eating.
  • It is important that you get laboratory tests done before you initiate therapy to rule out any other urological condition such as infections and prostate cancer. This is because prostate cancer also causes enlarged prostate.
  • Patients should wait for at least 6 months after the last dose of Avordart to donate blood.
  • Although there is not a strong evidence, Avodart may cause or worsen existing heart condition. You may need to undergo periodic cardiac monitoring to ensure the drug is not adversely affecting your heart.

Avodart-Capsules

How do I take the drug?

  • Stick to the prescribed dosage. Taking Avodart in larger doses can lead to over dosage and taking it in lesser amount will not produce the desired effects.
  • Swallow capsule with a glass of water.
  • You can take the drug both with and without food.
  • Chewing, crushing or opening the capsules can irritate your skin, lips, mouth, and throat. So swallow the capsules whole to prevent irritation.
  • Do not discontinue Avodart before talking to your physician. The symptoms may take up to six months to subside.
  • For the detection of optimal results by this drug and prevention of any adverse events, you might have to undergo blood testing. So you should not miss your follow-up.
  • Moisture and heat can damage the capsules, store Avodart at room temperature in a dry place.
  • Discard any capsule that is damaged or leaking. Consult your pharmacist on how to properly dispose of the defected capsules.

Contraindications and precautions

  • You should not take the drug if you are allergic to the whole drug or any other ingredient present in it.
  • The drug should strictly be avoided in all women and children.
  • Blood should not be donated till six months of last dose of Avodart.
  • Females should not handle this drug and should immediately wash their hands or any other skin area that has come in contact with the leaking capsule  
  • Before prescribing this medicine to a patient, thorough urological evaluation is required.
  • Monitor patients for any cardiac changes after initiating therapy with Avodart.

What are the adverse effects of the drug?

You may suffer from any or all of the following side effects of the drug;

  • Dizziness
  • Impotence or sterility
  • Decreased sexual desire (libido)
  • Difficulty in ejaculating
  • Breast disorders, such as enlarged breasts
  • Heart failure
  • Prostate cancer

Postmarketing Reports include;

  • Immune system disorders: Allergic reactions such as rash, itching (pruritis), hives (urticarial), swelling (edema) of dermis or other tissue such as subcutaneous and submucosa (angioedema).

Enlarged breasts (gynecomastia) and Breast cancer in men Depression

How can Avodart interact with the other drugs?

  • Digoxin: Avodart does not interfere with the absorption, distribution, metabolism and elimination of digoxin.
  • Cytochrome P450 3A Inhibitors: Dutasteride is metabolized by isoenzymes called CYP3A4 and CYP3A5 isoenzymes. It can interfere with the drugs that inhibit these enzymes.
  • Calcium Channel Blockers (CCBs): When administered concomitantly, CCBs hinder Avodart’s elimination resulting in increased blood concentration of the drug.
  • Alpha blockers: The drug-drug interaction between dutasteride and tamsulosin has not been appraised.
  • Warfarin: dutasteride can be given safely with warfarin.

Can this drug be used in the specific populations?

  • In pregnancy: Dutasteride belongs to the category X which means it is absolutely contraindicated in pregnancy. Animal studies have suggested that when dutasteride was given in pregnant females, it lad to genitalia malformation in male fetuses.
  • In nursing mothers: Avodart is secreted in breast milk, therefore contraindicated in nursing mothers.
  • In pediatrics: this drug is marked unsafe for children.
  • In geriatrics:  Avodart is considered safe in elderly.

Pharmacology of Avodart:

What is the mode of action of Avodart?

Avodart (dutasteride) selectively stops the functioning of enzyme 5-alpha-reductase that coverts testosterone into dihydrotestosterone (DHT), leading to betterment and improvement of symptoms associated with BPH.

What is the pharmacokinetics of this drug?

Absorption: Once the capsule of Avodart is swallowed, about 60% of dutasteride is able to enter the blood circulation. It can take up to 12 weeks to completely start showing its desired effects.

Distribution: A large amount of this drug binds to the plasma proteins present in the human body. 300-500-L gets distributed throughout the body.

Metabolism and Elimination: It is metabolized by the isoenzymes called CYP3A4 and CYP3A5. The major route of excretion for dutasteride is through feces. Less than 1% of the administered drug is eliminated through the urine.

How do different patient populations affect the Pharmacokinetics of this drug?

  • Elderly patients do not require any different or adjusted dosing with Avodart.
  • It is unknown whether racial differences affect the pharmacokinetic profile of Avodart.
  • It is yet to be determined if absorption, distribution, metabolism, and excretion get altered in patients having any kind of renal injury or failure.
  • How liver injury affects the working of Avodart in body is not known. It is established that dutasteride is metabolized maximum via human liver; therefore, the hepatic impairment can augment the effects produced by this drug in the body.

What is the toxicology profile of this drug?

  • Animal studies have shown Avodart to be able to produce benign tumors in liver cells specifically when used in female rats and mice.
  • It also increased the occurrence of tumors in the Leydig interstitial cells which form testosterone in the existence of luteinizing hormone in male mice.
  • During animal testing, sexually mature male rats’ reproductive systems and functioning was found to be adversely affected by this drug.
  • Researchers found that long term use of Avodart leads to central nervous system toxicity in animal test subjects.
  • Reduced weights of prostate of fetus and increased ovaries weight was discovered in animals during pre-clinical tests with Avodart.

What should you inform your doctor before using Avodart?

Before taking Avodart, you should inform your doctor about having a medical history of allergy to Avodart or other medicines such as finasteride (Propecia, Proscar) which are very similar to Avodart.

What are the ingredients used in Avodart capsules?

  • Active ingredients: dutasteride
  • Inactive ingredients: include edible red ink, gelatin, glycerin, mono-di-glycerides of caprylic/capric acid, butylated hydroxytoluene, titanium dioxide, ferric oxide (yellow).

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