dutasteride

Action and Spectrum

Actions and Spectrum: 

dutasteride is a medication used primarily to treat benign prostatic hyperplasia (BPH), which is a condition characterized by an enlarged prostate gland. It is also used to treat male pattern hair loss. dutasteride belongs to a class of drugs called 5-alpha-reductase inhibitors.

These drugs work by inhibiting the activity of the 5-alpha-reductase enzyme, which converts testosterone to dihydrotestosterone (DHT). DHT is a hormone that contributes to the growth of the prostate gland, and its inhibition can help to reduce the size of the prostate. 

In addition to its use in treating BPH, dutasteride has also been studied as a potential treatment for prostate cancer. Some studies have suggested that dutasteride may be effective in reducing the risk of developing prostate cancer in men at high risk for the disease. dutasteride has a long half-life, which means that it stays in the body for a long time after it is taken.

This can be an advantage in terms of reducing the risk of side effects, but it also means that it may take some time for the full effects of the medication to be seen. Common side effects of dutasteride include decreased sex drive, impotence, and breast enlargement or tenderness. In rare cases, it may also cause allergic reactions or liver damage. 

Drug Interaction

Adverse Reaction

Frequency defined 

1-10% 

Impotence 

Decreased libido 

Ejaculation disorder 

Breast disorders 

<1% 

Dizziness 

Frequency not defined 

Cardiac failure 

Prostate cancer 

Black Box Warning

There is no blackbox warning 

Contraindication / Caution

Contraindication/Caution: 

dutasteride has some contraindications and precautions that should be considered before use. 

• Women who are pregnant or may become pregnant should not handle dutasteride capsules due to the risk of harm to a developing male fetus. 
• dutasteride is contraindicated in individuals who are allergic to dutasteride or any of its components. 
• Men who have liver disease should use caution when taking dutasteride as it is metabolized in the liver. 
• dutasteride should not be used in conjunction with other 5-alpha-reductase inhibitors or medications used to treat BPH or hair loss. 
• dutasteride may affect the results of prostate-specific antigen (PSA) tests used to screen for prostate cancer. Men who are taking dutasteride should inform their healthcare provider before undergoing PSA testing. 
• dutasteride may increase the risk of developing high-grade prostate cancer. Men who have a history of prostate cancer or who have a family history of prostate cancer should use caution when taking dutasteride and consult their healthcare provider. 

Pregnancy / Lactation

Pregnancy consideration:  

Not recommended to be used in women 

Breastfeeding warnings:  

Not recommended to be used in women 

Pregnancy category: 

• Category A: Satisfactory and well-controlled studies show no risk to the fetus in the first or later trimester. 
• Category B: No evidence shown of risk to the fetus found in animal reproduction studies, and there are not enough studies on pregnant women. 
• Category C: Adverse effects on the fetus found with evidence in animal reproduction studies and no adequate evidence for a human product; Pregnant women must take care of the potential risks. 
• Category D: There is adequate data with sufficient evidence of human fetal risk from various platforms. However, despite potential dangers may be used only in emergencies for potential benefits. 
• Category X: Drugs listed in this category outweigh risks over benefits. The drug is not for pregnant women. 
• Category N: No data is available for the drug under this category. 

Pharmacology

Pharmacology: 

dutasteride is a 5-alpha-reductase inhibitor that works by inhibiting the activity of the 5-alpha-reductase enzyme. This enzyme converts testosterone to dihydrotestosterone (DHT), a hormone that is involved in the growth and development of the prostate gland. By inhibiting 5-alpha-reductase, dutasteride reduces the levels of DHT in the body, which can lead to a reduction in the size of the prostate gland. 

dutasteride is a competitive inhibitor of both types of 5-alpha-reductase (type 1 and type 2), which are found in different tissues in the body. Type 1 is primarily found in the skin and liver, while type 2 is primarily found in the prostate gland and hair follicles. By inhibiting both types of 5-alpha-reductase, dutasteride is able to reduce the levels of DHT in both the prostate gland and hair follicles, which is why it is also used in the treatment of male pattern hair loss. 

dutasteride is well-absorbed from the gastrointestinal tract, with peak plasma concentrations reached within 2-3 hours of oral administration. It has a long half-life of about 5 weeks, which means that it remains in the body for a relatively long time after it is taken. dutasteride is extensively metabolized in the liver, and its metabolites are excreted in the urine and feces. 

Pharmacodynamics: 

The pharmacodynamics of dutasteride are related to its mechanism of action as a 5-alpha-reductase inhibitor. By inhibiting the activity of the 5-alpha-reductase enzyme, dutasteride reduces the conversion of testosterone to dihydrotestosterone (DHT), which is a potent androgen involved in the growth and development of the prostate gland and hair follicles. 

Inhibition of 5-alpha-reductase by dutasteride results in a reduction in the levels of DHT in the serum and in target tissues such as the prostate gland and hair follicles. This reduction in DHT levels can lead to a reduction in the size of the prostate gland, an improvement in urinary symptoms associated with BPH, and an increase in hair growth in men with male pattern hair loss. 

dutasteride has been shown to reduce serum DHT levels by up to 98% within 24 hours of administration, and this reduction in DHT levels is sustained for up to 4 weeks after discontinuation of the drug. Dutasteride also reduces prostate volume by up to 25% after 6 months of treatment, and this reduction is maintained for up to 4 years of treatment. 

In addition to its effects on DHT levels, dutasteride has been shown to reduce the expression of genes involved in prostate cell proliferation and inflammation, and to increase the expression of genes involved in prostate cell apoptosis (programmed cell death). These effects may contribute to the observed reduction in prostate volume and improvement in urinary symptoms associated with BPH. 

Pharmacokinetics: 

Absorption 

The bioavailability is 60% 

The onset of action is 1-2 weeks 

Peak plasma concentration is achieved in 2-3 hours 

Distribution 

Protein bound is 99% 

The volume of distribution is 300-500 L 

Metabolism 

The drug is metabolized hepatically by P450 enzyme CYP3A4 & CYP3A5 

Elimination 

The half-life is 5 weeks (at steady state) 

The drug is excreted in feces (40%) and in urine (<1%) 

Adminstartion

Administration: 

dutasteride is typically administered orally in the form of a capsule. The capsules should be swallowed whole and should not be chewed or crushed. They can be taken with or without food. 

The recommended dose of dutasteride for the treatment of benign prostatic hyperplasia (BPH) is 0.5 mg taken once daily. The capsules should be taken at the same time each day, and it is important to take the medication as prescribed by your healthcare provider. 

For the treatment of male pattern hair loss, the recommended dose of dutasteride is also 0.5 mg taken once daily. The capsules should be taken at the same time each day, and it may take several months of treatment before an improvement in hair growth is noticed. 

It is important to continue taking dutasteride as prescribed, even if there is no immediate improvement in symptoms. It may take several months of treatment to see the full benefits of the medication. 

If a dose of dutasteride is missed, it should be taken as soon as possible. However, if it is almost time for the next dose, the missed dose should be skipped, and the regular dosing schedule resumed. It is important not to take a double dose to make up for a missed dose. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: dutasteride 

Pronounced: doo-TAS-ter-ide 

Why do we use dutasteride? 

dutasteride is used for the treatment of two conditions: 

• Benign prostatic hyperplasia (BPH): BPH is a condition in which the prostate gland becomes enlarged and can cause difficulty with urination. dutasteride works by inhibiting the activity of the 5-alpha-reductase enzyme, which reduces the levels of dihydrotestosterone (DHT) in the body. DHT is involved in the growth and development of the prostate gland, so by reducing DHT levels, dutasteride can lead to a reduction in the size of the prostate gland, which can improve urinary symptoms associated with BPH. 
• Male pattern hair loss: Male pattern hair loss is a common condition in which men experience thinning of hair on the scalp. dutasteride works by inhibiting the activity of the 5-alpha-reductase enzyme, which reduces the levels of DHT in hair follicles. DHT is involved in the miniaturization of hair follicles, so by reducing DHT levels, dutasteride can promote hair growth and slow down or stop hair loss in men with male pattern hair loss.