Dutasteride

Dutasteride (Avodart) is an 5-alpha-reductase inhibitor (similar to finasteride) that is used to treat benign prostatic hyperplasia (BPH; enlargement of the prostate gland) and male pattern hair loss (androgenic alopecia) ¹⁾, ²⁾, ³⁾, ⁴⁾. Dutasteride works by blocking the production of a natural substance that enlarges the prostate in benign prostatic hyperplasia (BPH) and in male pattern hair loss (androgenic alopecia) dutasteride blocks the 5-alpha reductase enzyme responsible for regulating the conversion of testosterone to dihydrotestosterone (DHT). By reducing dihydrotestosterone (DHT) levels in your scalp, dutasteride decreases dihydrotestosterone (DHT) effects on your hair follicles, reversing the process of hair loss in men. The use of oral 5-alpha-reductase inhibitors (dutasteride and finasteride) in women with female pattern hair loss (FPHL) is not approved by the FDA, and they are contraindicated for pregnant women because of their teratogenicity in the male fetus ⁵⁾.

Women and children should not use dutasteride. Pregnant women or women who may become pregnant should NOT use or handle dutasteride capsules. Dutasteride can be absorbed through the skin and can cause birth defects in male fetuses. Dutasteride can cause birth defects in male fetuses (Pregnancy Category X, i.e., drugs that have such a high risk of causing permanent damage to the fetus that they should not be used in pregnancy or when there is a possibility of pregnancy).

Dutasteride is available only with your doctor’s prescription.

In men with benign prostatic hyperplasia (BPH) Dutasteride is used alone or in combination with tamsulosin (Flomax) to treat men who have symptoms of an enlarged prostate gland, which is also known as benign prostatic hyperplasia (BPH). Benign enlargement of the prostate is a problem that can occur in men as they get older. The prostate gland is located below your bladder. As the prostate gland enlarges, certain muscles in the prostate gland may become tight and get in the way of the tube that drains urine from the bladder. This can cause problems with urinating, such as a need to urinate often, a weak stream when urinating, or a feeling of not being able to empty the bladder completely. Dutasteride may reduce your chance of developing acute urinary retention (sudden inability to urinate) and may also decrease the chance that prostate surgery will be needed.

In the prostate gland Dutasteride blocks the action of an enzyme called 5-alpha-reductase. The 5-alpha-reductase enzyme changes testosterone to another hormone that causes the prostate to grow. As a result, the size of the prostate is decreased. The effect of dutasteride lasts only as long as the medicine is taken. If it is stopped, the prostate begins to grow again.

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.

Dutasteride was approved for use in the United States in 2001 and is available in 0.5 mg capsules generically and under the trade name Avodart to be taken by mouth. Swallow the capsules whole; do not open chew, or crush them. A fixed dose combination of dutasteride (0.5 mg) with tamsulosin (0.4 mg: an alpha blocker) is available under the trade name Jalyn. The recommended dose of dutasteride is 0.5 mg once daily with or without food. Take dutasteride at around the same time every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take dutasteride exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Dutasteride is usually given long term and an effect is usually not seen until 3 to 6 months of therapy. Your symptoms may improve after you have taken dutasteride for 3 months, but it may take 6 months or longer for you to see the full benefit of dutasteride. Talk to your doctor about how you are feeling during your treatment. Dutasteride may control your symptoms but will not cure your condition. Continue to take dutasteride even if you feel well. Do not stop taking dutasteride without talking to your doctor.

Dutasteride side effects are uncommon, but include impotence and decreased libido, ejaculation disorders, overdevelopment or enlargement of the breast tissue in men (gynecomastia), dizziness and fatigue. Dutasteride also decreases serum prostate specific antigen (PSA) levels which should be monitored during therapy.

Ask your pharmacist or doctor for a copy of the manufacturer’s information for the patient.

Figure 1. Dutasteride mechanism of action

[Source ⁶⁾ ]

Finasteride versus Dutasteride safety profile

A study comparing the safety profile of dutasteride (0.5 mg/day) and finasteride (5 mg/day) for treating benign prostatic hyperplasia (BPH) was performed by Andriole et al ⁷⁾. In the dutasteride group of 813 subjects, impotence occurred in 7%, decreased libido in 5%, and ejaculation disorder in 1% ⁸⁾. Impotence was experienced by 8%, decreased libido by 6%, and ejaculation disorder by 1% in the finasteride 5mg group (n=817) ⁹⁾. These differences were not considered significant and the safety profile of dutasteride was considered no different than finasteride by the authors based on their parallel group, comparator trial ¹⁰⁾.

Kaplan et al. ¹¹⁾ conducted a retrospective analysis of 378 consecutive men treated at a single clinic with 5 alpha-reductase inhibitor monotherapy for lower urinary tract symptoms related to benign prostatic hyperplasia (BPH). Treatment duration was five years. Of those enrolled, 197 subjects were treated with finasteride 5 mg and 211 with dutasteride 0.5 mg ¹²⁾. At 5 years, 57.4% of men in the finasteride group and 42.5% of men in the dutasteride group remained on treatment ¹³⁾. Dutasteride resulted in more sexual side effects leading to discontinuation compared to finasteride, with the incidence of erectile dysfunction, ejaculatory dysfunction, and decreased libido being significantly higher in the dutasteride group (5.1%, 2.4%, 2.7%, respectively) compared with the finasteride group (2.1%, 1.8%, 1.4%, respectively) ¹⁴⁾. Of those subjects who remained on treatment for five years, dutasteride resulted in significantly greater erectile dysfunction than finasteride. At year 5, subjects on dutasteride therapy had significantly worsened International Index of Erectile Function scores relative to baseline than did those on finasteride ¹⁵⁾. This suggests that dutasteride may have stronger negative adverse sexual effects compared to finasteride ¹⁶⁾.

How effective is dutasteride for hair loss in men?

In Gubelin Harcha et al ¹⁷⁾ multicenter, randomized, double-blind, placebo-controlled study also compared dutasteride (0.02, 0.1, or 0.5 mg), finasteride (1 mg), and placebo in the treatment of androgenetic alopecia for 917 men (20-50 years old). Dutasteride 0.5mg was found to significantly increase hair growth compared to finasteride 1 mg and placebo with a similar rate of adverse side effects. Altered libido, impotence, and ejaculation disorders were listed for all groups (dutasteride 0.5mg: 4.9%, 5.4%, and 3.3%, respectively; finasteride 1mg: 6.7%, 6.1%, 3.9%, respectively; placebo: 1.7%, 3.9%, 3.3%, respectively) ¹⁸⁾. There was no significant difference found between finasteride and dutasteride sexual side effects and additionally, a dose dependent response of sexual side effects for any of the treatment doses of dutasteride was absent ¹⁹⁾. Sexual side effects were found to decrease over time.

In Gupta et al ²⁰⁾ study comparing of oral minoxidil, finasteride, and dutasteride for treating androgenetic alopecia, dutasteride 0.5 mg/day is probably more effective than finasteride 5 mg/day, minoxidil 5 mg/day, finasteride 1 mg/day, followed by minoxidil 0.25 mg/d. Oral minoxidil predominantly causes hypertrichosis and cardiovascular system (CVS) symptoms/signs in a dose-dependent manner, whereas oral finasteride and dutasteride are associated with sexual dysfunction and neuropsychiatric side effects ²¹⁾.

In the Olsen et al ²²⁾ androgenetic alopecia study comparing multiple doses of dutasteride (0.05 mg, 0.1 mg, 0.5 mg, 2.5 mg) versus finasteride 5 mg, dutasteride 0.5 mg was shown to be significantly superior at promoting hair growth compared to finasteride 5 mg after 24 weeks ²³⁾. Dutasteride 2.5mg was also shown to be significantly more effective than dutasteride 0.5 mg at increasing hair growth ²⁴⁾. Rates of decreased libido, ejaculation disorders, and impotence were 13%, 1%, and 0% for dutasteride 2.5 mg, respectively; 1%, 1%, and 0% for dutasteride 0.5mg, respectively; 4%, 3%, and 1% for finasteride 5mg, respectively; and 3%, 0%, and 5% for placebo, respectively ²⁵⁾. Of the 13% of subjects who reported decreased libido in the dutasteride 2.5 mg treatment group, 4 resolved during treatment, 1 within 3 weeks of stopping therapy, and 1 within 8 weeks of stopping; 1 patient had decreased libido that persisted after stopping but was considered by the patient to be unrelated to the drug ²⁶⁾. Based on these findings the authors suggest that while dutasteride 0.5 mg is the recommended daily dose for BPH (dutasteride is not FDA approved for androgenetic alopecia but it is prescribed for such as an off label use), dutasteride 2.5mg is significantly more effective at reducing DHT levels and thus could have a greater therapeutic impact at these levels.

Can women with hair loss use dutasteride?

The use of oral 5-alpha-reductase inhibitors (dutasteride and finasteride) in women with female pattern hair loss (FPHL) is not approved by the FDA, and they are contraindicated for pregnant women because of their teratogenicity in the male fetus ²⁷⁾.

Women and children should not use dutasteride. Pregnant women or women who may become pregnant should NOT use or handle dutasteride capsules. Dutasteride can be absorbed through the skin and can cause birth defects in male fetuses. Dutasteride can cause birth defects in male fetuses (Pregnancy Category X, i.e., drugs that have such a high risk of causing permanent damage to the fetus that they should not be used in pregnancy or when there is a possibility of pregnancy).

However, doctors have prescribed dutasteride off-label as a first-line treatment in post-menopausal women with female pattern hair loss (FPHL) ²⁸⁾, ²⁹⁾, ³⁰⁾, ³¹⁾, ³²⁾. The androgen dihydrotestosterone (DHT) is thought to play a large role in inducing androgenetic alopecia and is formed from the conversion of circulating testosterone to DHT by 5-alpha reductase.

Dutasteride can reduce serum DHT levels by 90% and has been reported to treat female pattern hair loss successfully with no side effects at doses that range from 0.25 to 0.5 mg/day ³³⁾. However, Dutasteride should not be given to women of childbearing age unless they are using birth control measures due to potential feminizing effects on the male fetus or to patients with impaired liver function

A recent network meta-analysis demonstrated that the increase in total hair count at 24 weeks with 0.5 mg/day of dutasteride was more efficacious compared to that with 1 mg/day finasteride with the similar adverse events profile ³⁴⁾, ³⁵⁾. Furthermore, a Korean group analyzed the long-term effectiveness and safety profiles of finasteride and dutasteride; they reported that dutasteride-treated patients showed more significant improvement in hair growth compared to finasteride-treated patients and both medications were analogously safe (possibly with a lower incidence of sexual adverse events than previously reported; dutasteride = 1.6%, and finasteride = 1.1%) ³⁶⁾. Accordingly, oral 5-alpha reductase inhibitors represent the first-line treatment modality for androgenetic alopecia because of their effectiveness and tolerability, and dutasteride further widened therapeutic options ³⁷⁾, ³⁸⁾.

Are there any contraindications for dutasteride?

Dutasteride results in a decrease in dihydrotestosterone (DHT). Since DHT is an important androgen in sexual development, children and women who are pregnant or planning on getting pregnant should avoid use. Dutasteride should also be avoided in any persons who have had a hypersensitivity to this medication ³⁹⁾.

Does dutasteride cause any interactions with other drugs?

Using dutasteride with any of the following medicines is usually not recommended, but may be required in some cases. 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
• Itraconazole

Using dutasteride 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.

Is dutasteride safe for long-term use in men?

Although dutasteride and finasteride have been established to be effective for the treatment of benign prostatic hyperplasia (BPH) and male pattern hair loss (androgenetic alopecia) by substantially reducing the levels of dihydrotestosterone (DHT) ⁴⁰⁾, ⁴¹⁾, it has also been documented that dutasteride and finasteride may increase the incidence of sexual dysfunction ⁴²⁾. Decreased libido, ejaculation disorder, and impotence are among the most commonly reported drug related side effects ⁴³⁾. Erectile dysfunction, or impotence, has been cited as the most common side effect in multiple studies for both finasteride 5 mg/day and dutasteride 0.5 mg/day, followed by decreased libido ⁴⁴⁾, ⁴⁵⁾, ⁴⁶⁾, ⁴⁷⁾, ⁴⁸⁾, ⁴⁹⁾. In the largest meta-analysis to date on5-alpha-reductase inhibitors, there was found to be a significantly increased risk of sexual dysfunction (156% increase) for men being treated with finasteride or dutasteride for benign prostatic hyperplasia (BPH), whereas there was not a significant association for those treated for androgenetic alopecia ⁵⁰⁾. Dutasteride 0.5 mg/day has also been shown to have a greater incidence of adverse sexual effects than finasteride 5 mg/day in the treatment of BPH ⁵¹⁾. Unfortunately, there is no consensus regarding the relation between 5-alpha-reductase inhibitors dosage and the likelihood of sexual dysfunction and further study is needed in this area ⁵²⁾, ⁵³⁾, ⁵⁴⁾. It is based on these findings that experts recommend doctors consider and discuss the possible sexual side effects and risk of depression with their patients prior to selecting a drug therapy ⁵⁵⁾.

How does dutasteride work?

Dutasteride is the successor to finasteride acting as a second‐generation 5‐alpha‐reductase inhibitor and functioning as a selective competitive inhibitor of type 1 and type 2 isoenzymes of 5‐alpha‐reductase designed to decrease the production of dihydrotestosterone (DHT) ⁵⁶⁾, ⁵⁷⁾, ⁵⁸⁾, ⁵⁹⁾. ⁶⁰⁾. Dutasteride is reported to be three times more potent at inhibiting the type 1 5‐alpha‐reductase enzyme and 100 times more potent at inhibiting the type 2I 5‐alpha‐reductase enzyme than finasteride ⁶¹⁾. Dutasteride comes in 2.5 and 5 mg doses, both of which have shown superior efficacy to finasteride 5 mg ⁶²⁾. Due to dutasteride’s large molecular size, it is difficult to formulate and deliver as a topical agent. However, its large size and fat soluble (lipophilic) nature contribute to it remaining on the scalp and preventing absorption into your body. If requested by clinicians, compounding pharmacies may formulate dutasteride topical solutions, although literature is sparse regarding its utility in treating androgenetic alopecia.

Dutasteride 0.5 mg/day can reduce dihydrotestosterone (DHT) serum levels by upwards of 90% in a dose dependent manner ⁶³⁾. By reducing dihydrotestosterone (DHT) levels in your scalp and your prostate gland, dutasteride decreases dihydrotestosterone (DHT) effects in your hair follicles and prostate gland, reversing the process of hair loss in men (androgenic alopecia) and reducing the size of your prostate in benign prostatic hyperplasia (BPH) ⁶⁴⁾.

Olszewska and Rudnicka ⁶⁵⁾ reported a case of a female patient with androgenetic alopecia who did not respond to minoxidil and initially benefited from finasteride. Given her persistent androgenetic alopecia, the patient was started on oral dutasteride. After 6 months of treatment, clinical and trichogram assessments revealed significant improvement in hair density ⁶⁶⁾. Several randomized, double‐blind, placebo‐controlled clinical studies have demonstrated dutasteride’s effectiveness for treating androgenetic alopecia ⁶⁷⁾, ⁶⁸⁾. Intradermal (injection into the skin) dutasteride was also reported in order to decrease the systemic side effects. Saceda‐Corralo et al. ⁶⁹⁾ administered 1 mL intradermal dutasteride 0.01% injections every 3 months for a total of three sessions to six subjects. Trichoscopy assessments revealed increased hair diameter and density, in addition to clinical improvement in androgenetic alopecia. There were no statistically significant differences in serum levels of total and free testosterone, 3 alpha androstanediol glucuronide, and dihydrotestosterone before and after treatment ⁷⁰⁾. Similar studies injecting dutasteride mesotherapy yielded promising results ⁷¹⁾, ⁷²⁾, ⁷³⁾. Overall, oral dutasteride appears to be superior to the intradermal route. However, more studies are warranted ⁷⁴⁾.

Overall, dutasteride has shown superior efficacy both in blocking DHT and promoting hair growth compared to finasteride. In a study of 399 patients, dutasteride was found to block 98.4% of DHT, while finasteride blocked about 70% ⁷⁵⁾. In another study of 416 men between 21 and 45 years of age, dutasteride was found to produce better hair count results than finasteride over a period of 12–24 weeks  ⁷⁶⁾. Despite the greater efficacy demonstrated by dutasteride, finasteride is still likely to be prescribed more often as a first‐line agent in treating male pattern baldness due to FDA approval and insurance coverage.

Dutasteride special precautions

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:

Men who have taken dutasteride 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.

Dutasteride 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 dutasteride.

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

Before taking dutasteride:

• tell your doctor and pharmacist if you are allergic to dutasteride, finasteride (Propecia, Proscar), any other medications, or any of the ingredients in dutasteride capsules. Ask your doctor or check the manufacturer’s patient information for a list of the ingredients.
• tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: antifungals such as ketoconazole (Nizoral); cimetidine (Tagamet); ciprofloxacin (Cipro); diltiazem (Cardizem, Dilacor, Tiazac); ritonavir, (Norvir), troleandomycin (TAO); and verapamil (Calan, Covera, Isoptin, Verelan). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• Dutasteride may increase your risk of developing high-grade prostate cancer. Tell your doctor if you have or have ever had liver disease or prostate cancer.
• you should know that dutasteride is for use only in men. Women, especially those who are or may become pregnant, should not handle dutasteride capsules. Touching the contents of the capsules may harm the fetus. If a woman who is pregnant or who could become pregnant accidentally touches leaking capsules, she should wash the area with soap and water immediately and call her doctor.
• you should know that you should not donate blood while you are taking dutasteride and for 6 months after you stop taking this medication.

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.

Children

Dutasteride is not indicated for use in children. Safety and efficacy have not been established.

Elderly people

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

Breastfeeding women

There are no adequate studies in women for determining infant risk when using dutasteride during breastfeeding. Weigh the potential benefits against the potential risks before taking dutasteride 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 dutasteride, 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 dutasteride with any of the following medicines is usually not recommended, but may be required in some cases. 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
• Itraconazole

Using dutasteride 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.

Medical Problems

The presence of other medical problems may affect the use of dutasteride. 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 dutasteride from the body.

Dutasteride uses

Dutasteride is a 5-alpha reductase inhibitor that is used alone or with another medication (tamsulosin [Flomax]) to treat symptomatic benign prostatic hypertrophy (BPH) ⁷⁷⁾, ⁷⁸⁾, ⁷⁹⁾, ⁸⁰⁾, ⁸¹⁾, ⁸²⁾. Dutasteride inhibits the conversion of testosterone to dihydrotestosterone (DHT), which is important in the development and maintenance of prostatic hyperplasia. Dihydrotesterone (DHT) levels decrease during dutasteride therapy, but serum testosterone levels do not. Dutasteride usually takes several months to have an effect on prostate size and the symptoms of prostatic hypertrophy (urinary hesitancy and poor stream), unlike the alpha-1 adrenergic receptor blockers (alpha blockers) which have a more immediate effect.

Doctors also use finasteride and dutasteride off-label as a first-line treatment for male pattern hair loss (androgenetic alopecia) and in post-menopausal women with female pattern hair loss (FPHL) ⁸³⁾, ⁸⁴⁾, ⁸⁵⁾, ⁸⁶⁾, ⁸⁷⁾, ⁸⁸⁾, ⁸⁹⁾, ⁹⁰⁾. The androgen dihydrotestosterone (DHT) is thought to play a large role in inducing androgenetic alopecia and is formed from the conversion of circulating testosterone to DHT by 5-alpha reductase.

Dutasteride can reduce serum DHT levels by 90% and has been reported to treat female pattern hair loss successfully with no side effects at doses that range from 0.25 to 0.5 mg/day ⁹¹⁾. However, Dutasteride should not be given to women of childbearing age unless they are using birth control measures due to potential feminizing effects on the male fetus or to patients with impaired liver function

A recent network meta-analysis demonstrated that the increase in total hair count at 24 weeks with 0.5 mg/day of dutasteride was more efficacious compared to that with 1 mg/day finasteride with the similar adverse events profile ⁹²⁾, ⁹³⁾. Furthermore, a Korean group analyzed the long-term effectiveness and safety profiles of finasteride and dutasteride; they reported that dutasteride-treated patients showed more significant improvement in hair growth compared to finasteride-treated patients and both medications were analogously safe (possibly with a lower incidence of sexual adverse events than previously reported; dutasteride = 1.6%, and finasteride = 1.1%) ⁹⁴⁾. Accordingly, oral 5-alpha reductase inhibitors represent the first-line treatment modality for androgenetic alopecia because of their effectiveness and tolerability, and dutasteride further widened therapeutic options ⁹⁵⁾, ⁹⁶⁾.

Dutasteride dosage

The dose of dutasteride will be different for different patients. Take dutasteride exactly 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. The following information includes only the average doses of dutasteride. If your dose is different, do not change it unless your doctor tells you to do so.

You may take dutasteride 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.

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

Benign Prostatic Hyperplasia

Treatment of symptomatic benign prostatic hyperplasia (BPH) in men with an enlarged prostate to reduce the risk of acute urinary retention and BPH-related surgery.

• Adults: 0.5 milligram (mg) once a day.

What should I do if I forget a dose?

If you miss a dose of dutasteride, 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.

Dutasteride side effects

Dutasteride may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• inability to have or maintain an erection
• decrease in sex drive or interest in sexual intercourse (libido)
• problems with ejaculation
• decreased sexual performance or desire
• impotence (inability in a man to achieve an erection or orgasm)
• inability to have or keep an erection (persistent erectile dysfunction)
• loss in sexual ability, desire, drive, or performance
• pain, soreness, swelling, or discharge from the breast or breasts

Rare side effects:

• chest pain or discomfort
• dilated neck veins
• extreme fatigue
• irregular breathing
• irregular heartbeat
• swelling of the face, fingers, feet, or lower legs
• trouble breathing
• weight gain

Incidence not known:

• blistering, flaking, or peeling of the skin
• cough
• difficulty with swallowing
• dizziness
• fast heartbeat
• hives or welts, itching skin, rash
• 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
• tightness in the chest
• unusual tiredness or weakness

Some side effects may be serious. If you experience any of these symptoms, call your doctor immediately or get emergency medical help:

• changes in the breasts such as increased size, lumps, pain, or nipple discharge
• swelling of the face, tongue, or throat
• difficulty breathing or swallowing
• peeling skin

Taking dutasteride may increase the risk that you will develop high-grade prostate cancer (a type of prostate cancer that spreads and grows more quickly than other types of prostate cancer). Talk to your doctor about the risks of taking dutasteride.

Dutasteride may cause other side effects. See your doctor if you have any unusual problems while taking dutasteride.

Dutasteride toxicity

In general, dutasteride appears to be a fairly safe drug, and so its use is recommended ⁹⁷⁾. A literature review by Hirshburg et al. ⁹⁸⁾ analyzed studies related to adverse events of 5-alpha reductase inhibitors in relation to prostate cancer, psychological effects, their use in women and sexual health.

In large and representative populations, an increase in the incidence of prostate cancer, or an increase in high-grade prostate cancers upon detection, or a variation in the survival rate were not associated with dutasteride ⁹⁹⁾. A direct link between the use of 5-alpha reductase inhibitors and depression was not established either ¹⁰⁰⁾. The same revision indicated that there were not many studies on the use of 5-alpha reductase inhibitors in women, but the current known risks to women include birth defects in male fetuses if taken during pregnancy, a decreased libido, headache, gastrointestinal problems, isolated cases of menstrual changes, acne and dizziness. Finally, it was reported that erectile dysfunction, a decreased libido and ejaculation disorders occurred in a fairly low percentage of men ¹⁰¹⁾.

In addition, the long-term effect of dutasteride on sexual alterations is interesting as it was associated with a significant increase in impotence, a decreased libido and ejaculation disorders during the first year when compared with a healthy control, but there were no significant differences between the two groups in the second year ¹⁰²⁾.

Currently, there are no long-term studies evaluating finasteride or dutasteride use in women ¹⁰³⁾. In a recent study, Price et al ¹⁰⁴⁾ followed 137 women aged 41 to 60 years for 12 months in a double-blind, placebo-controlled, randomized study conducted at eight investigational sites in United States and found no statistical difference in side effects of finasteride 1mg daily versus placebo ¹⁰⁵⁾. The only adverse event reported in the finasteride group was one case of folliculitis, which resolved with continued treatment ¹⁰⁶⁾. Shum et al ¹⁰⁷⁾ presented a case series of four women treated with finasteride 1.25 mg daily for up to 2.5 8. years without reported side effects. The longest trial of finasteride and dutasteride in women found during the literature search was three years by Boersma et al ¹⁰⁸⁾. Unfortunately, side effects were not discussed ¹⁰⁹⁾.